Solution

How to troubleshoot and locate faults in PT100 temperature transmitter?

• 1. First, look at 3 types of typical fault phenomena

  (1) No display, no output, stuck at 4mA → power supply / wiring / open circuit
  (2) Inaccurate display, zero drift, temperature too low / too high → wiring method, compensation, moisture, aging
  (3) Sudden value changes, erratic fluctuations, large swings → interference, grounding, three-wire system error, poor contact
• 2. Check power supply and loop (basic 80% of faults)

  (1) Measure the terminals of the two-wire temperature transmitter: Check whether voltage is within the normal range of the transmitter: large line drop, insufficient power capacity, long-distance loss
  (2) Measure output current: Fixed at 3.6mA: instrument self-test error, probe short circuit / fault Fixed at 4mA: PT100 open circuit, not connected, no temperature sensing Over 20mA: probe short circuit, motherboard damage Changes linearly with temperature normally: transmitter is fine, on-site process normal fluctuation
• 3. Key determination to distinguish "probe fault" or "transmitter module fault"

  Fastest on-site isolation method:
  Remove the three wires of the PT100 sensor and short-circuit the transmitter input If output returns to normal temperature zero point and is stable: PT100 probe itself is faulty Still error / erratic jump: temperature transmitter module itself is faulty Measure PT100 resistance (room temperature 25℃ standard) Normal:
  ≈109.6Ω Infinite:
  platinum resistor open circuit Close to 0Ω:
  short circuit Large deviation:
  aging, moisture, water ingress
• 4. Check wiring system (most common human error)

  Industrial requirement: three-wire PT100 Common errors:
  (1) Use two-wire: wiring resistance adds up, temperature reading high, drift
  (2) Three-wire misconnected, colors not distinguished, mixed: error of tens of degrees
  (3) Three wires of different thickness, too long distance: compensation fails Key point: two wires of the same color in three leads are the compensation ends, must be connected to the transmitter compensation terminals simultaneously to eliminate cable resistance.
• 5. Locate moisture, water ingress, condensation faults (high occurrence on site)

  Phenomenon:
  value drifts, sometimes high sometimes low, worse in rainy weather Causes:
  
  (1) Water ingress or condensation in junction box
  (2) Poor sealing of protective tube, water vapor enters platinum resistor core Treatment:
  dry, seal waterproof, replace waterproof connector, use glue for moisture protection
• 6. Electromagnetic interference, grounding, shielding troubleshooting (main cause of erratic jumps)

  (1) Power cable and signal line in same conduit, close to inverter / motor → interference and erratic jumps
  (2) Shielding layer grounded at both ends → ground loop, value fluctuation Correct method:
  (1) Shielding layer grounded at one end (control cabinet side)
  (2) Temperature control signal line in separate conduit away from power line
  (3) In strong interference conditions, use isolated type temperature transmitter
• 7. On-site zero / range drift calibration

  (1) Compare with standard thermometer at room temperature and observe deviation
  (2) Local button or handheld operator:
  (3) Correct zero drift
  (4) Recalibrate range
  (5) Deviation fixed and cannot be corrected: sensor aging, replace directly
• 8. Safety precautions

  (1) Shut down and cool high-temperature equipment before disassembly to prevent burns
  (2) Prohibit opening covers with power on or modifying wiring in explosion-proof areas
  (3) In corrosive conditions, avoid medium exposure that could corrode skin

How to quickly locate and troubleshoot a malfunction in an ultrasonic flowmeter?

• 1. First classify three typical faults

  (1) No flow rate, no flow, zero display, weak signal → Probe coupling/pipe/medium/installation straight pipe section
  (2) The flow rate jumps, fluctuates between large and small, and the values are fluctuating→ bubbles, scaling, interference, and incorrect installation
  (3) Measurement is too large/small, inaccurate→ Parameter setting, range matching, sound velocity, and pipe wall input error
• 2. Look at the instrument [signal strength / signal-to-noise ratio] core judgment (fastest)

  (1) Normal:
  signal strength ≥ 80%, good signal-to-noise ratio, and stable value
  (2) Low signal and no wave found: The coupling paste dries out, the probe is displaced, and the pipe rusts and scales too thickly The rubber lining/anti-corrosion layer is too thick, and the plastic pipe wall thickness parameters are selected incorrectly
  (3) Signal intermittency: the medium contains bubbles, suspended solids, and pulsating water Treatment:
  Reapply couplant, align the probe, polish the pipe wall, and correct the pipe parameters
• 3. Investigation of media working conditions (80% on-site roots)

  (1) Liquid with bubbles/vaporization Phenomenon:
  Readings jump, flow fluctuations, and instability Causes:
  negative pressure at the pump inlet, pressure relief, pipeline intake, high temperature vaporization Solution:
  Change the measurement point to the positive pressure area, away from the pump outlet/highest point of gas accumulation Exhaust and eliminate negative pressure suction
  (2) Serious scaling, silt, and rust of pipes The external clip-on type is most feared: the sound absorption of the dirt layer→ poor penetration, and the measurement is small/immovable Solution:
  clean the pipe wall, replace the measuring point, and switch to the pipe section type/electromagnetism
  (3) Liquid accumulation in unfull pipes and pipelines It must be measured with a full tube, and if the tube is not full, it is directly inaccurate and there is no signal
• 4. Installation & rigid verification of straight pipe section (high-frequency pit stepping)

  (1) Insufficient upstream straight pipe section (elbow, valve, reducer, pump) Requirements:
  Standard: 10DN in the front, 5DN in the back The flow field → disordered→ runout and large error of the close resistance part
  (2) The probe spacing and installation point are paired incorrectly The model (V method / Z method / W method) is selected incorrectly and the distance input is incorrect Re-use the instrument's built-in spacing calculation function to locate the punch hole
  (3) Wrong installation orientation Horizontal tube: Probe mount at 3–4 o'clock on the side It is forbidden to install directly above (gas accumulation) and directly below (sediment)
• 5. Parameter setting verification (large human error)

  Focus on 5 items:
  (1) Pipe outer diameter, wall thickness, material (carbon steel / stainless steel / PPR)
  (2) Lining thickness and whether there is anti-corrosion lining
  (3) Sound velocity parameters of liquid type (water/sewage/oil).
  (4) Range, unit, damping filter settings (the filter is too small and easy to skip, too large and slow to respond)
  (5) Zero point calibration and static zero point drift compensation If one parameter is wrong, the error is directly more than ten percent.
• 6. Electrical, interference and power supply investigation

  (1) Unstable power supply, large voltage drop→ Abnormal motherboard operation
  (2) The signal line is not well shielded, and the power line of the frequency converter is in the same slot→ interfering and jumping Treatment:
  Separate wiring and shielding single-ended grounding Stay away from motors, frequency converters, solenoid valves Install a signal isolator

Malfunctions and Solutions of Ultrasonic Level Gauge?

• 1. Core Diagnostic Entry Point: Check Echo Quality First

  Menu: Check Echo Strength / Signal-to-Noise Ratio Strong and Stable Echo: Instrument is basically normal; usually parameters / interference issues Weak, Missing, or Fluctuating Echo: Operational conditions, installation, or probe problems
• 2. Instrument Displays Normally, But Reading Remains 0 / Cannot Measure Liquid Level

  Causes:
  
  (1) Actual liquid level is within the blind zone (cannot be detected in the near field)
  (2) Probe condensation, water droplet attachment, dust accumulation causing ultrasonic attenuation
  (3) Large amount of foam, vapor, or mist on the liquid surface absorbing the sound wave
  (4) Range set too small, working conditions exceed the range
  (5) Tilted installation, probe facing tank wall / beam / pipe, causing false echo blockage Solutions:
  
  (1) Check the blind zone, install higher or use a model with a smaller blind zone
  (2) Clean the probe, add a purge / rainproof & dustproof cover / anti-condensation cover
  (3) For foam / dense vapor conditions: switch to 80G radar / guided wave radar
  (4) Recalculate range, leave 1.2 times margin
  (5) Reinstall: position away from tank wall, obstacles, or feed inlets
• 3. Erratic Values, Up-and-Down Drift, Fluctuating Readings

  Causes:
  
  (1) Large liquid surface fluctuations, stirring, water impact disturbances
  (2) Electromagnetic interference: frequency converters or motors in the same cable tray, poor grounding
  (3) Filter damping set too low, response too fast
  (4) Steel structures, ladders, or pipes inside the tank creating false echoes Solutions:
  
  (1) Install stilling tube / flow guide tube to stabilize liquid surface
  (2) Route signal line separately in conduit, single-end shield grounding, keep away from power/frequency lines
  (3) Increase time damping / filter averaging in menu
  (4) Enable false echo suppression, shield fixed interfering objects
• 4. Inaccurate Readings for Static Empty / Full Tank, Zero Shift

  (1) Long-term temperature and humidity changes causing zero drift
  (2) Water intrusion in probe or condensation in junction box causing moisture
  (3) Ultrasound velocity temperature compensation failure Solutions:
  
  (1) Execute zero calibration / empty calibration for static empty tank
  (2) Dry and seal, replace waterproof joints with anti-moisture sealant
  (3) Enable automatic temperature compensation to correct medium sound velocity
• 5. Unstable Measurement in Tanks with Steam, Mist, or Volatile Substances

  Causes:
  Water vapor or organic solvent mist absorbs ultrasound, scattering and attenuating the sound wave Solution:
  Ordinary ultrasound is unsuitable for heavy steam; use frequency-modulated radar / guided wave radar
• 6. Probe Corrosion, Aging, or No Emission

  Symptoms:
  No echo, silent probe, sensor fault error Solutions:
  Check cable breakage, water ingress, breakdown; replace with corrosion-resistant PVDF probe
• 7. Wiring and Power Supply Issues

  Symptoms:
  No display, current fixed at 3.6mA / 4mA / 22mA 3.6mA: Self-test fault, probe abnormal 4mA stuck: No echo, open loop 22mA: Overrange Solutions:
  Measure actual DC24V power supply, check polarity, terminal oxidation, and shield grounding

How to quickly locate and troubleshoot gear flow meter malfunctions?

• 1. let's take a look at the rapid classification of three types of typical phenomena

  (1) No volume, no pulse, no movement, no accumulation→ jamming, blockage, no rotation, and empty pipeline
  (2) The flow rate is small, the measurement is small, the error is large→ wear, viscosity is not matched, slippage, and bypass leakage
  (3) Reading drift, going and stopping, loud noise, jitter, → bubbles, impurities jamming, pressure pulsation
• 2. Quick judgment of the mechanical body (the fastest core)

  (1) Check whether there is medium flow on site, whether the front and rear valves are fully open, and whether the filter is blocked
  (2) Touch the shell: Abnormal noise and vibration: gear jam impurities, bearing wear, dry wear No rotation, no shaking: jamming, no pressure at the inlet, and solidification of the medium
  (3) Check the pre-Y-filter The filter is blocked→ there is a lack of liquid, the gear does not rotate, and the metering is stagnant Clean the filter and discharge pollutants regularly
• 3. The meter does not count, the pulse has no output, and the instantaneous is 0 Common causes:

  (1) The medium contains large particles, iron filings, → gears are stuck
  (2) Low temperature and high viscosity solidification, thickening in winter→ The gear belt cannot move
  (3) The inlet pressure is too low, the negative pressure is suction, and the material is cut off
  (4) The transmitting probe falls off, the Hall sensor is damaged, and the line is broken
  (5) The internal bearing is worn and the rotor is bitten to death Resolution:
  
  (1) Disassemble and clean the cavity and clean up impurities
  (2) High viscosity medium is equipped with heat tracing and heat preservation
  (3) Increase the inlet pressure difference and avoid negative pressure
  (4) Check the pulse wiring, sensor clearance, and replace the transmitting component
• 4. Inaccurate measurement, slowness, and lack of total amount

  Common causes:
  
  (1) Long-term use of gears/cavities wear, large gaps→ internal leakage and backflow
  (2) If the viscosity of the medium is too low (such as water, dilute solvent), → slip slip volumetric failure
  (3) Import and export loading reverse (easy to ignore)
  (4) Insufficient pressure difference, insufficient load, and low-speed leakage
  (5) Seal aging, bypass leakage Resolution:
  
  (1) Switch to turbine/electromagnetic for low-viscosity media; High viscosity selection special clearance model
  (2) Check the direction of the import and export arrows
  (3) Serious wear and tear return to the factory for pairing grinding or replacement
  (4) Check whether the pipeline bypass is leaking
• 5. The meter head moves and stops, jumps, and intermittently measures

  Common causes:
  
  (1) The medium is mixed with a large amount of air, bubbles, → idling false pulses
  (2) Pipeline pulsation and pump intermittent oil supply
  (3) The distance of the transmitting sensor is too far and the signal is intermittent
  (4) Local slight jamming, sometimes jamming and sometimes rotating Resolution:
  
  (1) Install exhaust valves upstream to eliminate air blockages
  (2) Stabilize the pump pressure and add a buffer tank
  (3) Adjust the Hall probe induction distance and shield the wiring to prevent interference
• 6. Temperature and pressure related, inaccurate in winter, high temperature leakage

  (1) Low temperature: viscosity soars→ large resistance, difficult start, and no volume Install insulation jackets and heat tracing
  (2) High temperature: seal aging and deformation, expansion gap increase→ internal leakage is large Replace high-temperature FKM / special seals
• 7. Electrical signal fault location (remote transmission 4-20mA / pulse)

  (1) No pulse: broken probe, broken shielding wire, grounding interference at both ends of the shield
  (2) Fixed current 4mA: no rotation signal, body not working
  (3) Numerical jumping: strong frequency conversion interference and poor grounding Treatment:
  
  (1) The signal line is routed separately and away from the motor frequency converter
  (2) Single-ended grounding of the shielding layer
  (3) Check whether the power supply DC24V is stable
• 8. Daily prevention (90% reduction in failures)

  (1) The front end must be equipped with a precision filter
  (2) It is strictly forbidden to use ultra-low viscosity pure water/dilute solvents for a long time
  (3) High viscosity medium in winter insulation, shutdown and emptying
  (4) Avoid idling, dry grinding, and liquid-free operation

Malfunctions and Solutions of Magnetic Resistance Floating Ball Liquid Level Sensor

• 1. Magnetoresistive float level sensor (rod type / analog 4-20mA) for accurate fault troubleshooting + solution on site

  Principle: The float has a built-in magnet → the magnetoresistive sensing array in the probe rod senses the magnetic field → outputs the corresponding liquid level signal The five root causes of common problems are: float jamming, magnet demagnetization/detachment, water condensation in the probe, electromagnetic interference, and scale coating
• 2. 3 minutes of basic checks

  (1) Power supply wiring 24V DC as standard, the measurement voltage cannot be less than 18V; The terminals are not loose or oxidized; The shielded cable is grounded at one end, away from frequency converters and power cables, and it is forbidden to walk with the high-voltage bridge.
  (2) Mechanical degrees of freedom The sensor is installed vertically (inclination angle <3°), and the float ball has no scaling, no debris jamming, no sticking, no winding, and smooth slide up and down throughout the process.
  (3) Magnetic verification If you use an iron tool close to the float, the magnetic attraction is strong = the magnet is normal; Weak suction / no magnetic suction = magnet demagnetization, detachment, direct replacement of float.
  (4) Sealing and waterproofing Junction box and cable inlet are free of condensation and water seepage; The probe rod is well sealed, and water ingress will directly burn the internal reluctance chip.
• 3. High-frequency typical faults + symptomatic solution

  Fault 1: The liquid level is fixed and stuck at 0%/full scale Cause
  (1) The float is stuck by silt, scale, and pipe wall, and cannot slide
  (2) The magnet falls off, demagnetizes at high temperature, and the magnetic field coupling fails
  (3) The magnetoresistive sensing element inside the probe rod is burned out and broken
  (4) The range parameters are incorrectly modified, and the full zero point is misplaced
  Solved
  (1) Stop the machine to clean the tank, wipe the probe, dredge the float activity area, and install the guide anti-jam tube
  (2) Detect the suction of the magnetic steel and replace the anti-corrosion float directly if it fails
  (3) Manually toggle the float up and down, and the signal does not change → The probe assembly is scrapped and replaced
  (4) Restore the factory settings and recalibrate the 4mA empty liquid level and 20mA full liquid level
  Fault 2: Numerical runout drift, high and low instability Cause
  (1) The liquid level tumbles, the water inlet impacts, and the float does not have a steady flow structure shaking
  (2) On-site frequency conversion equipment and motors generate electromagnetic interference
  (3) The probe rod is slightly damp, the insulation drops, and the signal is cluttered
  (4) The instrument filter damping setting is too small
  Solved
  (1) Install a still water well/stabilizer to isolate the disturbance of water flow
  (2) Optimize shielding grounding, install signal isolators, and increase the damping time of instrument software
  (3) The drying junction box is waterproof and sealed, and the probe rod is directly replaced when water enters, and cannot be repaired
  Fault 3: No output, black screen, 4mA unchanged all the time Cause power supply disconnection, reverse wiring, signal wire disconnection; the lowest level of the float card; The internal reluctance motherboard is damaged
  Solved measured power supply voltage, fastening wiring calibration positive and negative poles; Manually raise the float out of the water body, synchronized current rise = normal, no change = sensor replacement
  Fault 4: The high display is displayed all year round, and the full-scale alarm does not drop Cause The float is stuck in the upper limit, and the magnet is close to the probe; Internal circuit short circuit; Water ingress in the cavity
  Solved Check for float card position faults; disassemble the junction box after power off to observe the condensation water traces; If there is water/short circuit, it will be replaced directly to rematch the installation stroke
  Fault 5: Inaccurate measurement and error increase year by year Cause Probe rod/float fouling coating and shielding of magnetic field; installation tilt; Long-term high-temperature magnet attenuation
  Solved Soft cotton cloth clean the surface scale with water (hard objects are not allowed to scratch the probe); Correction of vertical installation; The high-temperature medium is selected with high temperature resistance and strong magnetism, and the zero point range is calibrated once a year
• 4. On-site minimalist self-test (no need to dismantle pipes)

  (1) No-load suspension: the float is ≈ 4mA to the end, the float is ≈ 20mA to the top, and the linear stable change = intact
  (2) Magnetic test: iron adsorption float is strong = magnet is normal
  (3) Shaking sound: There is a sound of water inside the probe = water inlet is scrapped

How to quickly locate and troubleshoot a malfunction in an electromagnetic flowmeter (3)

• 1. Pre-check: First confirm if measurement is possible

  (1) Electromagnetic measurement only works for conductive liquids, with medium conductivity ≥ 5 μS/cm
  (2) Pure water, oils, organic solvents, gases → cannot be measured themselves, not considered a fault
• 2. Three typical phenomenon classifications

  (1) Flow always 0, not moving, no display → power supply / wiring / empty pipe / excitation / electrode contamination
  (2) Flow fluctuates, drifts, suddenly large or small → poor grounding / bubbles / interference / liner material adhesion
  (3) Measurement too high or too low, cumulative inaccurate → pipe diameter and flow velocity mismatch, wrong parameters, zero point drift
• 3. Basic electrical troubleshooting

  (1) Check power supply Two-wire DC24V actual measurement: 18–28V normal, low voltage causes crash or drift
  (2) Check 4-20mA loop Fixed 4mA: no flow, empty pipe, electrode open circuit, excitation abnormal Above 20mA: range set too small, signal overload
  (3) Wiring inspection Do not reverse positive and negative, terminals free from looseness and oxidation; Signal cables must not run in the same conduit with power / frequency conversion cables
• 4. Empty/full pipe, electrode and liner faults (common)

  (1) Display empty pipe alarm, but there is water Electrode scaling, oil stain, attached insulating substances → signal acquisition failure Solution:
  stop and flush, soak electrodes in weak acid to clean; scraping with hard objects is prohibited
  (2) Pipe not full, negative pressure suction Creates false level, unstable electric field → erratic reading Correction: install lower, ensure full pipe year-round, vent high points
  (3) Liner wear, peeling, bulging Long-term use with corrosive medium, insulation damage → internal short-circuit drift
• 5. Step three: Grounding and excitation circuit (main cause of erratic readings)

  (1) No grounding ring on metal anticorrosive pipe / plastic pipe Cannot form reference potential → values fluctuate wildly Must be installed: stainless steel grounding ring / grounding electrode
  (2) Shielding layer wiring wrong Should only ground one end at control cabinet, grounding both ends causes ground loop interference
  (3) Excitation coil water ingress, insulation deterioration Performance: temperature rise, zero point drift, intermittent errors; needs drying or factory return
• 6. Medium condition issues

  (1) Liquid contains many bubbles, sand Bubbles interrupt sensing signal → sometimes zero, sometimes large Solution:
  vent upstream, install flow stabilizing tank
  (2) High viscosity, wall-adhering crystals Electrodes covered, weak induction → measurement too low Solution:
  regular flushing, use PTFE liner, self-cleaning structure
• 6. Medium condition issues

  (1) Liquid contains many bubbles, sand Bubbles interrupt sensing signal → sometimes zero, sometimes large Solution:
  vent upstream, install flow stabilizing tank
  (2) High viscosity, wall-adhering crystals Electrodes covered, weak induction → measurement too low Solution:
  regular flushing, use PTFE liner, self-cleaning structure
• 7. Parameter calibration errors

  (1) Wrong pipe diameter, range, pulse coefficient → overall deviation
  (2) Zero point not static calibrated → baseline exists under no load Solution:
  stop, fill pipe, let static zero be cleared, empty pipe calibration
• 8. Safety precautions

  (1) Do not disassemble sensor under pressure to prevent medium ejection
  (2) Corrosive, high-temperature conditions should be stopped, cooled, and depressurized before maintenance
  (3) Do not open covers with power on in explosive environments

Malfunctions and Solutions of Capacitive Liquid Level Gauge

• I. Typical Faults

  (1) Liquid level does not move or is stuck at 4mA / fixed at a certain value
  (2) Value drift, jumps erratically with changes in temperature or humidity
  (3) Large deviation at no load, small deviation at full load, overall measurement error
  (4) Direct over-range >20mA
• II. Rapid Electrical Circuit Diagnosis (Priority Troubleshooting)

  (1) Measure power supply: DC24V terminal actual voltage 18–28V Below 16V: large voltage drop, insufficient power load, causing drift or freeze
  (2) Measure output current to determine status Constant 4mA: no change in probe, insulation breakdown, circuit disconnection, abnormal no-load recognition Constant >20mA: probe short-circuit, sheath damaged and damp, over-range Follows liquid level slowly but inaccurate: calibration / dielectric / material deposition problem
  (3) Wiring & Shielding Signal lines should be independently threaded through conduits, away from inverter power cables; Shield layer should be grounded at one end (control cabinet), grounding at both ends causes circulating current and jumps; Check for oxidation, water ingress, or looseness at wiring terminals.
• III. On-site Quick Distinction Between "Instrument Head Fault" or "Probe Fault"

  Simplest isolation method:
  (1) Disconnect on-site probe, perform simulated calibration / short-circuit check
  (2) If instrument output changes normally → problem is with the probe itself on site
  (3) If fault remains unchanged → replace conversion circuit board / instrument head
• IV. High-Frequency Core Issues — Probe Insulation, Moisture, Condensation, Anti-Corrosion

  Damage
  (1) PTFE / PFA sheath cracking, scratching, aging Medium penetration, moisture → parasitic capacitance surge Symptom: zero point drift, reading at no load, the higher the temperature, the more it drifts Solution:
  Check appearance, dry, reseal; probe must be replaced if damaged
  (2) Junction box / sealing head condensation and water ingress Most common during rainy season or with steam tanks Symptom: value drifts slowly and irregularly Solution:
  Drying, waterproof sealant, extended anti-moisture sealing gland, split installation (high-temperature steam)
• V. Material Deposition, Adhesion, Crystallization Causing False Liquid Level

  Operating conditions: viscous liquid, slurry, sewage, scaling, humid powder Symptom: Tank shows high level even when emptied, liquid level does not drop, delayed readings Cause: film or probe deposits create fixed parasitic capacitance Solution:
  
  (1) Clean probe surface of deposits
  (2) Perform empty tank zeroing, deposit compensation, drift self-calibration
  (3) For easily adhered materials: must use fully covered PFA, anti-adhesion, intelligent compensation type; ordinary capacitive probes cannot completely resolve
• VI. Dielectric Constant Mismatch Causing Measurement Inaccuracy

  (1) High dielectric (aqueous solution / acid-base): normal for standard models
  (2) Low dielectric (oil products, organic solvents, dry plastic granules) Insufficient sensitivity, poor linearity, jumps Solution:
  Enable low-dielectric gain parameters, special calibration; severe cases require replacing with RF admittance continuous level transmitter
• VII. Installation Interference Causing Abnormalities

  (1) Probe too close to metal tank wall, supports, stiffeners (<150mm) Electric field interference → jumps, deviation Correction: eccentric installation, away from metal structures
  (2) Directly facing feed impact, stirring zone Material splashing, dynamic capacitance disturbance → reading jumps Correction: install protective sleeve, avoid feed drop area, increase software damping and filtering
• VIII. Zero / Range Calibration Failure

  Long-term usage, medium replacement, maintenance without re-calibration Manifestation: overall high/low readings, poor linearity Standard Operation: Calibrate zero with empty tank at rest → calibrate full-scale with full tank → confirm linearity follows

Float switch malfunction and solution

• 1. First, distinguish between the two commonly used structures

  (1) Cable-type float (commonly used in pump water tanks): internal steel ball contacts with swing angle
  (2) Linkage reed switch float (multi-point control in industrial tanks): magnetic steel, reed switch induction
• 2. Appearance and installation base inspection

  (1) Check if the housing is cracked, has water ingress, or leakage (internal short circuit due to water ingress / contact corrosion always causes failure)
  (2) Check for cable jacket damage, pulling, soaking aging, terminal looseness and oxidation
  (3) Check for installation jamming: against walls, blocked by pipes, entangled debris, the float cannot rotate freely
  (4) Check if the medium temperature exceeds the rated value (PP generally ≤60°C, excessive temperature causes deformation and leakage)
• 3. Float does not move, pump does not start / does not stop (contacts do not switch)

  Causes:
  
  (1) Float is stuck by debris or pipe wall, cannot swing into position
  (2) Internal steel ball / contacts oxidized, burned, or sticky
  (3) Linkage type: magnetic steel fallen off, reed switch burnt, stuck in position
  (4) Counterweight ball in wrong position, high and low level difference incorrectly set Troubleshooting:
  (1) Manually swing the float, listen for internal rolling of steel balls
  (2) No sound: internal stuck / damaged, replace directly
  (3) Sound present but no power conduction: contact oxidized or burned
  (4) Adjust counterweight ball position, remove external mechanical obstruction
• 4. False action, frequent start/stop, erratic behavior

  Causes:
  
  (1) Water flow fluctuation, surge causing float to swing frequently and switch
  (2) Internal contacts slight arcing, poor connection
  (3) Cable too long, shaking or suspended swinging
  (4) Linkage type: nearby steel structure magnetic field interference, float moving up and down Solutions:
  
  (1) Add anti-surge tube, flow stabilizing baffle
  (2) Control circuit add intermediate relay isolation (do not directly drive a high-power pump)
  (3) Secure the cable, reduce suspended swing distance
• 5. Housing water ingress, leakage failure

  Phenomenon:
  intermittent, poor insulation, electric leakage, tripping Diagnosis: shake float and listen for water sound, surface condensation and whitening Solution:
  Small sealed models cannot be repaired, replace directly; Do not pry open for repair, sealing failure will quickly recur
• 6. Wiring and electrical matching issues

  (1) Normally open / normally closed reversed: water supply becomes drainage, logic reversed
  (2) Directly driving high-power pump: contact current overload causes burn and sticking Correct method: float only controls the contactor coil, does not directly drive the main pump
  (3) Voltage mismatch: AC220/DC24 mixed use, internal breakdown
• 7. Corrosive environment aging failure

  Acid, alkali, sewage, chlorinated water: PP housing cracks, sealing ages, cable hydrolysis stiffens Solution:
  replace with PVDF corrosion-resistant models, PUR corrosion-resistant cables

Malfunctions and Solutions of Radar Level Gauge

• 1. General pre-check

  (1) Power supply and wiring DC24V normal voltage drop≥18V; The terminals are not loose or oxidized; it is strictly forbidden to connect positive and negative; The shielded cable is grounded at one end, and it is not the same as the frequency converter and power cable.
  (5) Grounding and anti-interference The instrument housing is independently protected and it is forbidden to connect to the neutral wire; The tank farm is isolated from frequency conversion mixing and pumps to avoid high-frequency clutter interference with 80G radio frequency.
  (3) Core installation taboo (80G top priority) Stay away from the feed splash area, tank wall stiffeners, ladders, and baffles; The flange is coaxial in the center and not eccentric; Do not install in the center of the manhole; Avoid condensation, dripping, and dust from sticking to the horn antenna.
• 2. Precise and radical treatment of high-frequency typical faults

  Fault 1: Empty tank shows liquid level, zero point is high, fixed false level Core Reasons: The 80G beam is extremely narrow, and it is easy to detect fixed echoes generated by flange end faces, tank bottom bosses, and antenna condensate/ash accumulation Resolution:
  
  (1) Stop the machine to clean the horn antenna, dry the condensation, and blow off the dust;
  (2) Execute the instrument menu: empty tank baseline calibration / false echo suppression (surface suppression), shield fixed interference echo;
  (3) Modify the starting ranging and blind spot offset parameters, and ignore the interference of nearby flanges.
  Fault 2: Large liquid level runout and frequent drift fluctuations Core Reasons: The liquid level tumbling, foam, volatile mist, tank vibration, and damping filter settings are too small Resolution:
  
  (1) Menu increases software damping / echo average filtering time (3~10s);
  (2) A large amount of foam/water vapor: 80G itself is adaptable, and if it is still unstable, you can add a waveguide/balance casing to stabilize the liquid level;
  (3) Reinforce the mounting bracket to eliminate mechanical vibration; Rectify the shielding and grounding to isolate electromagnetic interference.
  Fault 3: There is actual material, the instrument shows 0, and the liquid level cannot be detected Core Reasons: Low dielectric dielectrics (light oil, plastic particles), liquid level entering the near-field blind zone, antenna damage, range configuration reversal Resolution:
  
  (1) Check the dielectric constant of the medium, and confirm that the low dielectric is selected as a high-gain 80G radar;
  (2) Check the blind spot parameters and low cut-off distance of the instrument to avoid the liquid level falling in the measurement dead zone;
  (3) Check the horn antenna for corrosion, cracking, deformation, and replace it directly if damaged;
  (4) Correction range: empty can = zero point, full can corresponding to correct setting.
  Fault 4: Antenna mounting, crystallization, and condensation lead to inaccurate measurement (80G Most Common Field Problems) Resolution:
  
  (1) Sticky materials, easy to crystallize: purge type/anti-condensation horn, PTFE dust cover;
  (2) Compressed air regularly purge the antenna, and it is forbidden to scratch the horn surface with hard objects;
  (3) Large temperature difference in the tank produces condensation: increase the top of the tank insulation and anti-condensation steam accessories.
  Fault 5: 4-20mA output is inaccurate, no current, and full-scale jamming Resolution:
  
  (1) The measured circuit of the multimeter is on and off, and the short circuit, false connection, and line loss are checked;
  (2) Reconfiguration: confirm that 4mA = empty liquid level, 20mA = full liquid level, and redo the current calibration;
  (3) The line is normal but still has no output: the motherboard analog module is faulty, and the factory is returned for maintenance.
  Fault 6: HART/Modbus communication cannot be connected Solution:
  Unified device address, baud rate; check the positive and negative poles of the communication line; long-line matching terminal resistors; Stay away from sources of power interference.

How to troubleshoot and locate thermocouple faults

• 1. Basic 3-Minute Pre-Check

  (1) Inspect appearance and wiring Check for damaged insulation, water immersion, overheating, charred wires, terminal oxidation and blackening, loose crimping; Thermocouple compensating wires must not mix different types (K with K, E with E) and must not be connected randomly with regular copper wires.
  (2) Check the cold junction (junction box / cabinet) Large cold junction temperature fluctuations, direct sunlight, heat, or proximity to cables can cause temperature drift and inaccurate readings.
  (3) Check insulation and grounding Protective tubes damaged or damp, ceramic tubes cracked, thermometer elements leaking to ground.
• 2. Four Typical Malfunction Symptoms, Causes, and Solutions

  (1) Instrument displays [Overrange, HH, OL, Maximum value] Common causes:
  Thermocouple open circuit or burnt; compensating wire broken; terminal loose or internal ceramic tube breakdown. Handling: Power off and disconnect wires, use a multimeter in resistance mode to measure both ends of the thermocouple: Infinite resistance = burnt, replace thermocouple/temperature sensing element; High resistance = loose connection, retighten the crimp.
  (2) Instrument displays [Negative, low, large temperature drift] Common causes:
  Compensating wire polarity reversed (most frequent on site); Cold junction uncompensated, large cold junction temperature difference; Thermocouple aging, high-temperature annealing accuracy decline. Handling: Verify polarity, switch positive and negative; Enable instrument cold junction temperature compensation; Long-term high-temperature drift: replace with a new thermocouple.
  (3) Temperature jumps, erratic readings, fluctuating high and low Common causes:
  Poor terminal contact, vibration causing loose connection, damp leaking, interference (power lines of AC drives routed together) Handling: Tighten terminals, secure clips; Dry junction box, ensure waterproof sealing; Shielded compensating wire grounded at one end, keep away from power cables and drive cabinets; Protective tube damp: clean with alcohol and dry.
  (4) Inaccurate temperature, large steady-state deviation Common causes:
  Wrong type selected (mixing K/S/J/E), insufficient insertion depth, protective tube with coking or scale, medium corrosion, uneven temperature field Handling: Confirm correct type designation; Insertion depth ≥ 1/3 of the tube diameter, avoid touching tube walls; Clean protective tube of oil, dust, or coke deposits; For corrosive conditions, replace with corrosion-resistant, wear-resistant thermocouple.
• 3. Simple Multimeter Test for Good or Bad (on-site operation)

  (1) Continuity / resistance measurement Normal:
  tens to hundreds of ohms (depending on length) Infinite = open circuit, discard Near 0 ohms / conduction to ground = short circuit, leakage
  (2) Millivolt judgment (precise) Heat the temperature sensing end, measure mV with an instrument; if the corresponding table shows a linear increase = normal; no change = damaged.

How to troubleshoot and locate faults in thermal resistors

RTD (PT100/PT1000) On-site Quick Fault Diagnosis and Solutions

• 1. First distinguish the wiring (key basics)

  2-wire: only measures resistance, large error, easy to drift 3-wire: industrial mainstream, compensates lead wire resistance, accurate temperature measurement 4-wire: high-precision laboratory use On-site, first verify the instrument configuration: it must match the actual wiring method.
• 2. Quick multimeter test (measure with power off)

  PT100 standard resistance at room temperature: 25°C ≈ 109.6Ω Normal:
  resistance changes slowly and smoothly with temperature Resistance infinite → open circuit Resistance close to 0Ω → short circuit Resistance fluctuates → poor contact / damp leakage
• 3. Common fault symptoms, causes, solutions

  (1) Instrument shows maximum value, overrange, HH Cause: RTD sensor wire broken, lead wire broken, terminal loose, internal burn-out Solution:
  If multimeter measures infinite resistance, directly replace the probe Tighten terminals inside the panel, ensure proper crimping to prevent vibration loosening
  (2) Displays negative numbers, temperature too low, fixed deviation Cause: Three-wire connected incorrectly (wrong color or random connection) Lead wire copper too long without resistance compensation Probe installed against pipe wall, not inserted deeply enough Solution:
  Check the three wires by color group, reconnect correctly; ensure insertion depth ≥ 1/3 of the pipe, not touching the wall
  (3) Temperature fluctuates, values drift Common causes:
  Oxidized or loose terminal, damp/water ingress, insulation degradation, interference from power lines / frequency converters on the same cable tray Solution:
  Clean oxidized terminals, tighten screws Dry the junction box, provide waterproof sealing, replace moisture-proof silicone Route signal wires separately, shielded end grounded, away from high-voltage power cables
  (4) Temperature measurement inaccurate, large steady-state deviation Cause: Wrong model selected (mixing PT100/PT1000) Protective tube scaling, oil contamination, aging Environmental heat radiation, installation location dead spots Solution:
  Verify nominal type; remove and clean protective tube dirt; adjust measurement point to avoid heat source dead spots
  (5) Three-wire system gradually increases error Cause: Resistance of the three compensation wires is unbalanced Solution:
  Check if the three wires have the same cross-section and length; enable three-wire compensation function on the instrument.

How to quickly locate and troubleshoot a malfunction in a hot gas mass flowmeter (3)

• Step 1: Identify the fault phenomenon

  First, it is necessary to accurately identify the specific fault phenomena exhibited by the flow meter, which can help us quickly narrow down the scope of troubleshooting. Common breakdowns include: 1. No display: The screen does not light up at all. 2. There is flow but the reading is zero: There is gas flow in the pipe, but the meter shows zero. 3. No flow but no reading is zero: There is no gas flow in the pipeline, but the meter shows a flow value (zero drift). 4. Large fluctuations in readings: The flow display value is unstable and jumps frequently. 5. Low Measurement: The flow rate display value is consistently lower than the actual flow. 6. Abnormal output signal: The output signal such as 4-20mA or RS-485 does not match the displayed value.
• Step 2: Locate the cause according to the phenomenon

  According to the fault phenomenon determined in the first step, in-depth investigation is carried out from the following aspects. 1. Power and display issues If the flow meter is not displaying, check in the following order: Check the power supply: Confirm that the power supply is turned on and the voltage is normal. Check the wiring: Check if the power cord polarity is reversed (especially when powered by 24V DC). Check the internal components: Observe if the power indicator lights up. If the light is on but the screen is not on, the display may be loose or damaged; If the light does not come on, the internal switching power supply may be damaged. 2. Media and process conditions Changes in the state and process of the gas being measured are common causes of abnormal readings. Gas Composition Variations: Confirm that the actual measured gas type is exactly the same as the internal settings of the flow meter. Changes in gas composition can directly affect thermal conductivity, leading to inaccurate measurements. Media contamination: If the gas contains impurities such as oil mist, water droplets, and dust, it will adhere to the sensor probe to form an "insulating layer", resulting in a decrease in heat transfer efficiency, manifested as low readings or zero readings in severe contamination. Media with Liquid or Gasification: The presence of droplets or liquid vaporization in the pipeline can significantly interfere with the heat exchange process, leading to wild fluctuations in readings or false flow rates during downtime. Flow Pulsation: Pulsating currents from upstream compressors, pumps, and other equipment, or frequent valve adjustments, can cause large fluctuations in readings. 3. Installation and piping environment Incorrect installation and complex piping environments can directly affect measurement accuracy. Improper Mounting: Installed near elbows, valves, or reducers, the flow meter can create turbulence, leading to large fluctuations in readings. It should be ensured that there are enough straight pipe sections in front and behind the flow meter (usually 10D before 5D, D is the pipe diameter). Incorrect probe installation: The probe is inserted at the wrong depth or in the wrong orientation, resulting in low or no readings. External interference: Strong electromagnetic devices such as frequency converters and large motors nearby may interfere with signal transmission, leading to fluctuations in readings or abnormal output signals. It is necessary to check whether the signal line shielding and grounding are good. Pipeline blockage: Foreign objects such as stones and welding slag in the pipeline may block the flow meter entrance, resulting in an abnormal increase in pressure drop and the flow rate cannot pass normally. 4. Meter settings and status Incorrect parameter settings or changes in the gauge's own state are also important troubleshooting points. Incorrect Parameter Settings: Check whether parameters such as range, gas type, flow unit, pipe diameter, etc. are set correctly. Incorrect settings are a common cause of inaccurate readings. Zero Drift: After a period of use, the meter may drift at the zero point, resulting in a non-zero display when there is no flow. Re-zeroing is required to ensure that there is no flow in the pipeline. Small Flow Exclusion: If a small flow cut value is set, traffic below that value is displayed as zero, which may mask the true small flow. Faulty Sensor/Electronic Components: Aging sensors, damage, or faulty internal circuitry can cause various abnormal readings, such as stuck readings, no output, or display error codes
• Step 3: Execute the solution

  Power Supply Problems: Check and connect the power supply to correct wiring polarity. Damaged internal components: contact the supplier for factory repair. Gas Composition Changes: Check and correct gas type settings within the meter. Sensor Contamination: Carefully clean the sensor probe using anhydrous ethanol and a soft cloth. Liquid/pulsating media: Gas-liquid separators, filters or buffer tanks are installed upstream. Improper installation position: Adjust the installation position to ensure sufficient straight pipe sections. Probe installation error: Reinstall according to the instructions, ensuring correct orientation and depth. External Interference: Check and improve the shielding and grounding of signal lines. Parameter setting error: Check and correct parameters such as range and unit. Zero Drift: Perform zero point calibration in a static no-flow state. The damping coefficient is too small: appropriately increase the damping (filtering) time to smooth the reading. Sensor damage: Contact the supplier for detection or replacement.

Fault and solution of RF admittance level switch

• 1. Not working at all: no display, no light, no action

  Typical phenomena: no response to power-on, no indicator light, and no suction of the relay.
  (1) Power supply problems (most common) Measured with a multimeter: 24VDC (±10%) or 220VAC is normal. Check: Empty, fuse, whether the terminal is loose / oxidized, whether the polarity is reversed. Handling: Replace the fuse of the same specification; Re-crimp the terminals; Correct positive and negative poles.
  (2) Internal circuit failure Performance: The power supply is normal and still unresponsive, and the insurance is burned as soon as it is powered on. Treatment:
  Most of the motherboard/power module is damaged→ Replace the meter head or return to the factory for repair.
• 2. Short positions are also alarmed (false alarm, constant light)

  Typical phenomenon: the silo is empty, the switch still shows "charge", and the relay keeps sucking.
  (1) Probe hanging/fouling (90% on-site causes) Reason: Dust, wet, and adhesive materials adhere to the probe and are regarded as "material". Treatment:
  If the empty position is powered off, remove the probe and wipe it clean with anhydrous alcohol + soft cloth; After reloading, the short position is re-zeroed (key!). ）。
  (2) The sensitivity is too high Reason: If the adjustment is too sensitive at the factory or before, it will be triggered by a slight hanging. Processing: Adjust the sensitivity clockwise (generally there is a coarse C, a fine F), and the green light can be stable when the position is empty.
  (3) Poor grounding/interference Reasons: No grounding, poor grounding, and a frequency converter / large motor nearby. Treatment:
  The instrument shell is connected to the earth separately (not the neutral wire); Shielding wires for signal lines and away from power lines; If necessary, filter or change the installation position.
  (4) The insulation of the probe is damaged Phenomenon:
  The probe and silo wall resistance is very small (<100kΩ), water ingress/cracking. Treatment:
  Replace the probe (not repairable).
• 3. Do not call the police when there is material (omission, no action)

  Typical phenomena: no trigger when the material is full, the indicator light does not turn on, and the relay does not work.
  (1) The sensitivity is too low Processing: Increase the sensitivity counterclockwise until the red light is on and the relay is in motion when the probe is expected.
  (2) The probe is installed in the wrong position Reason: Loading too high/too low, too close to the wall, and being impacted by the material flow is crooked. Processing: Adjust to the normal submersion of the material level, and install it firmly vertically / horizontally.
  (3) The probe is dirty but not clean Treatment:
  Thorough cleaning + recalibration.
  (4) The relay is damaged or the output is reversed Processing: Relay on and off; Check whether the normally open/normally closed (NO/NC) is reversed.
• 4. Alarm jumping, relay jitter (unstable)

  (1) Material level fluctuation/material flow shock Treatment:
  Increase the delay (5–10 seconds) to avoid instantaneous false triggers.
  (2) Interference/poor grounding Treatment:
  Grounding, shielding, and staying away from interference sources in the "false alarm".
  (3) Probe looseness/vibration Handling: Tighten the probe and reinforce the mounting bracket.
• 5. It is still not allowed after calibration/calibration

  (1) The empty position must be adjusted to zero and the full position must be calibrated Steps: Short position → zero (green light, no alarm); Let the material just pass the probe → adjust the sensitivity/calibration (red light on, alarm); Fix it and don't mess with the knob anymore.
  (2) Change of medium (dry/wet, material change) Processing: recalibration; If necessary, replace the adaptive probe (e.g. insulating probe for conductive materials).

Malfunctions and Solutions of Input Liquid Level Sensor

Immersible Hydrostatic Level Sensor (Level Transmitter) Full Troubleshooting Guide + Solutions Applicable to: Water tanks, sewage tanks, deep wells, hydrostatic immersible 4-20mA level meters

• I. Basic Quick Inspection

  (1) Power Supply Check Standard supply: DC 24V Measured below 18V → Excessive voltage drop, aging power source, wire gauge too thin Voltage normal but not working → Display circuit board failure
  (2) Venting Pressure Tube (Most Critical, Often Overlooked) The immersible type uses negative pressure ventilation to compensate atmospheric pressure: Blocked vent, water ingress, condensation, bending → Zero drift, inaccurate readings Vent cable must not be submerged, blocked, or knotted
  (3) Wiring Polarity and Shielding Reversed polarity: No display, no output Shield layer: Single-ended grounding, keep away from inverters and pump power lines
  (4) Probe Diaphragm Bottom diaphragm covered with sludge, scale, debris, scratches → Low readings, stuck
  (5) Installation Location Avoid water impact zones, vortex areas, pump intakes; prevent probe from being pressed on the bottom
• II. Typical Faults + Causes + Solutions

  Fault 1: Display shows full scale, value stuck at maximum Common Causes:
  
  (1) Overload on diaphragm, sensor core damaged
  (2) Signal line short-circuited, water infiltration
  (3) Vent pressure blockage causing negative pressure imbalance Solution:
  Remove and test in air: Normal zero → On-site water pressure/installation issue If still full scale → Probe burned out/core breakdown, replace directly Clean vent tube, dry internal condensation
  Fault 2: Level does not move, fixed value, false level Common Causes:
  
  (1) Probe buried in sludge, bottom sediment pressing diaphragm
  (2) Vent tube blocked, condensation
  (3) Range parameters mistakenly changed Solution:
  Lift probe and rinse bottom diaphragm, remove sand and debris Clear vent cable and air-dry Verify 4mA = empty, 20mA = full, restore range settings
  Fault 3: Level low, large measurement error, zero drift High-frequency core issue: Vent compensation failure Other causes: Diaphragm scaling, temperature drift, cable dampness Solution:
  Drain tank and perform zero calibration Clean pressure-sensing diaphragm (rinse with soft water, no scraping with hard objects) Check vent cable for clear ventilation path, prevent rainwater backflow
  Fault 4: Values jump, fluctuate, keep drifting Causes:
  
  (1) Pump start/stop, water flow impact, vortex disturbance
  (2) Poor cable shielding, inverter interference
  (3) Oxidized terminals, poor contact, moisture leakage Solution:
  Install anti-interference guard tube for probe, stabilize flow in stilling well Increase instrument filter damping time Retighten terminals, single-ended shield grounding, separate power lines
  Fault 5: 4–20mA output abnormal, no current, current unchanged Troubleshooting: Measure current with no load: Should be around 4mA without water Circuit open / poor connection → redo connections Current stuck unchanged → circuit board damaged, return or replace
  Fault 6: Water ingress, display condensation, internal leakage Causes:
  Seal aging, cable root damage, long-term immersion Solution:
  Short-term drying for emergency; Severe leakage requires direct replacement, not repair
• III. Quick On-Site Judgment with Multimeter

  Measure power supply: DC 24V normal In air without water: Standard output ≈ 4mA, normal Significantly higher/lower/stagnant → Sensor fault Press diaphragm lightly: Current rises smoothly = Core intact No change/jumping = Damaged

How to quickly locate and troubleshoot a malfunction in a vortex flowmeter

Vortex Flowmeter On-site Quick Troubleshooting + Solution
Applicable: steam, gas, liquid, compressed air vortex pulse / 4-20mA type

• 1. The basic start-up must be checked

  (1) Power supply DC24V normal; Low voltage, large voltage drop, virtual connection, reverse connection→ no display, no output
  (2) Installation of straight pipe section (vortex core) 10D ≥ front, 5D ≥ rear; valves, elbows, pumps, and diameter reductions are installed nearby→ and the metering is large/runout
  (3) Grounding and interference Sensor shielding single-ended grounding; Stay away from frequency converters, motors, and power cables to prevent power frequency interference
  (4) The lower limit flow rate under working conditions The vortex street has a starting flow, and the small flow is below the lower limit→ it does not go and is displayed as 0
• 2. Typical fault phenomena + causes + treatment

  (1) The pipeline has flow, and the instrument shows 0 and does not go out Common causes:
  Actual flow rate is lower than starting flow rate (gas/steam is the most common) The probe swirl detects dirt, scale, water accumulation, and wear Pulse signal wire breakage, poor contact, motherboard amplification circuit damage The valve is not fully open and the throttling is serious Resolution:
  Confirm whether the flow rate of the working condition is within the range; cleaning of vortex generators and probe impurities; Check that the wiring is tight and the shielding is intact; open upstream valves and rectify straight pipe sections; Replace the wide-range vortex street or booster under small flow conditions
  (2) Traffic jumps, large fluctuations in value, and irregular drift Causes of high incidence: Pipe vibration, water hammer, pressure pulsation Strong electromagnetic interference (frequency conversion, welding machine) The damping filter setting is too small The medium contains liquid, impurities, and two-phase flow Resolution:
  Menu increases software damping/filtering time; pipeline reinforcement and shock absorption, elimination of water hammer; Separate grounding, shielding and isolation, and separate wiring of power lines; Gas installation of steam and water separator and sewage discharge; Two-phase current is not suitable for vortex streets, replace other meters
  (3) There is no medium in the air traffic tube, and the instrument is randomly measured and spontaneously pulsed Cause: Pipe vibration resonance Interference in series and poor grounding The probe is damp and the insulation falls The sensitivity is too high Resolution:
  reduced trigger sensitivity; Improve grounding and shielding; Drying the junction box and making waterproof seals; Eliminate pipeline resonance and reinforce support
  (4) The measurement is large/small, the accumulation is inaccurate, and the error is large Cause: The straight pipe section is insufficient and the installation is eccentric Medium temperature and pressure not compensated (steam/gas mandatory) Parameter settings: pipe diameter, coefficient, density, and range error The generator hangs dirt and changes the shape of the throttle Resolution:
  rectification of the front and rear straight pipe sections, centered installation; The temperature and pressure compensation type must be invested in real-time temperature and pressure compensation; Check the K-factor and caliber unit of the instrument; disassemble and clean the vortex generator; Re-on-site calibration
  (5) 4-20mA output abnormal, full load, no current, stuck Cause: Loop short circuit, disconnection, load resistance exceeding the standard The range is set incorrectly The motherboard DA conversion module is damaged Resolution:
  universal meter measurement loop; Check 4mA zero flow rate and 20mA full flow; recalibrate analog outputs; Hardware damage returned to the factory
  (6) Steam special is common: condensation, seismic gauge, reading floating Resolution:
  Thermal insulation and heat tracing, bottom sewage discharge, shock absorbing bracket, increased filtering, and real-time compensation of temperature and pressure
• 3. The multimeter is simple and quick to judge the quality of the meter

  (1) The power supply is normal 24V
  (2) No flow: the pulse output has no jumping, and the current is stable at about 4mA
  (3) Simulated airflow / touch probe: the pulse follows the change→ the probe is normal No change→ Sensing / Motherboard damage

How to quickly locate and troubleshoot a malfunction in a turbine flowmeter (2)

Turbine Flow Meter On-site Quick Troubleshooting + Full Solution Applicable: Liquid / Pure Water / Diesel / Lubricating Oil / Organic Solvent Pulse Type, 4-20mA Turbine

• 1. Pre-check

  Power supply inspection DC24V / internal power supply battery version; The voltage is low, false connection, reverse connection→ no pulse, no display. Flow and installation The body arrow must be consistent with the flow direction of the medium; Front and rear straight pipe sections: front ≥ 10D, rear ≥ 5D; It is strictly forbidden to reverse installation, eccentric installation, and gasket retraction and throttling. Filtration and impurities (turbines are most feared) The front end must be equipped with a filter; Rust, welding slag, and particles can get stuck in the impeller and wear out the bearing. Medium working conditions It is forbidden to suction gas and liquid two-phase, empty pipe, and negative pressure; The bubbles will jump and pulse frequently.
• 2. Typical faults + causes + precise solutions

  Fault 1: There is a flow rate in the pipeline, and the meter shows 0 and does not go count Core Reasons:
  (1) The impeller is stuck, the bearing is worn and locked, and the debris is stuck
  (2) The pre-filter is blocked, and there is no actual flow
  (3) Pulse signal line breakage, shielding short circuit, probe failure
  (4) The flow rate is lower than the starting flow, and the range selection is large Resolution:
  
  (1) Disassemble and inspect the surface body, clean up impurities, manually toggle the impeller, and rotate smoothly to normal; Stuck replacement bearing/impeller
  (2) Cleaning the pre-filter and dredging the sewage
  (3) Use a multimeter to measure the pulse on and off, the quality of the induction probe, and redo the wiring
  (4) Replace the micro/low starting flow turbine in small flow situations
  Fault 2: Random traffic jumps, large and small values, and multiple metering for no reason Causes of high incidence:
  (1) The medium contains bubbles, negative pressure intake, and the pipeline is not exhausted
  (2) Pipeline vibration and electromagnetic interference (frequency converter, welding machine)
  (3) The impeller is slightly scratched and the bearing clearance is large
  (4) The sensitivity is too high and the filter damping is too small Resolution:
  
  (1) Install an exhaust valve at the high point to eliminate air masses when the pipe is full
  (2) Instrument enlargement software filtering/damping; Separate grounding, shielded single-ended grounding, away from power cables
  (3) Disassemble and inspect and correct the impeller clearance and replace the wear parts
  (4) Reduce the triggering sensitivity and suppress clutter false triggering
  Fault 3: Measurement is too large/small, cumulative is inaccurate, and the error is excessive Cause:
  (1) Installation inversion, insufficient straight pipe section, and sealing gasket protruding into the pipe
  (2) Long-term wear: bearing and impeller wear, speed deviation
  (3) Wrong parameters: the instrument coefficient K, caliber, density, and range are set incorrectly
  (4) The viscosity of the medium does not match the calibration (high incidence of oil) Resolution:
  
  (1) Check the flow direction arrow, rectify the straight pipe section, and trim the gasket
  (2) Replace the movement assembly with serious wear
  (3) Check the K factor of the factory nameplate and re-enter the configuration
  (4) Recalibrate the high-viscosity medium or replace the adapted model
  Fault 4: The air conditioning tube does not drain liquid, and the instrument automatically runs volume and emits false pulses Cause:
  (1) The pipeline resonance and slight jitter drive the impeller to idle
  (2) The induction probe is damp, the insulation drops, and the signal is interfered
  (3) Negative pressure suction and trace air hammer disturbance at the installation position Resolution:
  reinforced pipeline shock absorption; Drying junction box waterproof sealing; Optimized grounding shielding; Adjust the mounting point
  Fault 5: Abnormal 4–20mA output, full scale, no current, stuttering Cause: Signal loop break/short circuit, load resistance exceeded limit, range configuration error, motherboard output damage Resolution:
  multimeter measurement loop; Check 4mA zero flow rate and 20mA full flow; recalibrate the analog quantity; Hardware failure return to the factory for repair
  Fault 6: Easy to stutter, short service life (common problem on site) Resolution:
  Upstream standard filter + sewage discharge; Hard impurities are strictly prohibited; cemented carbide bearings are used for wear-prone media; Avoid dry rotation and idling
• 3. Simple on-site quality judgment (no need to dismantle large pipes)

  (1) The power supply is normal
  (2) No flow: pulse stationary, current stability≈ 4mA normal
  (3) Manual plucking impeller: the pulse changes evenly→ the probe + motherboard is intact; No change → sensor damage

How to quickly locate and troubleshoot a pressure transmitter malfunction

• 1. First, divide the phenomena into three major categories:

  (1) No display, no current, no signal → Power supply / loop / wiring issues
  (2) Values don't change, stuck, full scale, zero not responding → Diaphragm blockage, negative pressure, hardware damage
  (3) Value drift, fluctuation, sudden high or low → Interference, grounding, condensation, installation impulse pressure problems
• 2. Basic electrical troubleshooting (80% of faults occur here)

  (1) Check supply voltage Two-wire system: terminal measured DC 18–28V is normal Below 16V: excessive voltage drop, insufficient power capacity, long line loss High voltage: power supply voltage regulation damaged, may burn the mainboard
  (2) Check loop current (core judgment) Normal:
  4–20mA linearly corresponds to pressure under stable static pressure Fixed at 3.6mA: motherboard fault / sensor self-test error Fixed at 22mA: overrange, diaphragm overload damage Always 4mA: zero point stuck, impulse line blocked, no pressure applied
  (3) Check wiring and continuity Check for reversed polarity, loose terminals, oxidation, poor connection Shielding layer should be grounded at one end only; grounding at both ends is prohibited (ground loop interference causes value jumps) Long lines should be checked for short circuits, insulation damage, water ingress
• 3. On-site pressure and zero point calibration (quickly distinguish instrument or working condition)

  (1) Power off and restart: exclude freeze or software drift
  (2) Release pressure to atmosphere to check zero Normal:
  returns to 4mA, displays 0 Does not zero: zero point drift, locally reset zero using button Still off: sensor aging, diaphragm plastic deformation due to pressure
  (3) Manual pressure application / compare with standard pressure gauge Follows linear change: instrument normal, on-site process pressure fluctuation Does not follow: transmitter body fault
• 4. Impulse line & installation fault diagnosis (high frequency on site)

  (1) Impulse line blockage / crystallization / oil sediment accumulation Phenomenon:
  pressure unchanged, slow response, stuck Action: clean, purge, insulation and heating, install buffer
  (2) Pressure line air accumulation / air lock (liquid pipeline) Phenomenon:
  value drift, slight fluctuation Action: vent at high points, route pipes reasonably
  (3) Condensation water impact (steam measurement) Insufficient condensate in trap, direct high-temperature impact on diaphragm → temperature drift, damage
  (4) Wrong installation position Pump outlet, elbows, turbulent areas → impact pulsation, unstable readings
• 5. Interference, grounding, isolation problems (main cause of digital fluctuation)

  (1) Strong interference: VFDs, motors, solenoid valves in the same cable tray
  (2) No grounding / poor grounding: housing or shield not reliably grounded
  (3) No isolation: ground loops, common-mode interference Solutions:
  Route power and signal lines separately Use isolated transmitter Ground shield at instrument end only Install signal isolator
• 6. Medium corrosion, diaphragm damage judgment

  (1) Corrosion leakage: 316L not resistant to chloride ions / strong acid → diaphragm pitting, slow leak, drift
  (2) Water hammer impact, transient high pressure → overload, elastomer deformation, permanent error
  (3) Viscous, caking, sticking material → poor static pressure transmission, false pressure Action: replace with Hastelloy / tantalum diaphragm, install diaphragm seal, anti-clog isolator
• 7. Safety precautions

  (1) For high-pressure conditions, release pressure before removing instrument to prevent spraying injuries
  (2) Prevent splashing of corrosive media, wear protection
  (3) Explosion-proof areas strictly prohibit opening live covers

Fault and solution of tuning fork level switch

• 1. First, Understand Normal Operating Logic

  (1) No-load: Tuning fork oscillates at high frequency, output shows no material signal
  (2) Covered by material: Fork body damping stops oscillation → relay flips, output shows material alarm
• 2. No response when powered, no detection, always shows no material

  Core causes:
  (1) Power supply abnormal: DC24V/AC220V unstable, loose wiring, reversed polarity
  (2) Fork body stuck with material, caked, wet material adhesion, long-term false damping lock
  (3) Vibration chip damaged, internal circuit fault, water condensation
  (4) Installed directly facing falling material flow, material bridging under fork, actually not touching material Troubleshooting:
  (1) Measure actual supply voltage, tighten terminals, check polarity
  (2) Clean fork body dirt and caking, wipe dry moisture-attached substances
  (3) Manually hold / lightly touch fork body: If action switches: instrument normal, work condition issue with material / bridging No change: vibration chip / circuit board damaged, replace directly
  (4) Move fork to avoid direct falling material flow, add protective deflector plate
• 3. False alarm in empty bin, misoperation, always shows material

  Core causes:
  (1) Fork body adheres tiny powder, moist material, water condensation film, forming false damping
  (2) Bin strongly vibrates, stirring resonance, causing tuning fork mis-stop
  (3) Sensitivity set too high, slight interference triggers
  (4) Junction box water ingress, poor sealing, circuit leakage Troubleshooting:
  (1) Thoroughly clean fork body, dry to prevent moisture
  (2) Lower sensitivity, enable delay filtering (0.5–3s debounce)
  (3) Use shock-absorbing support, keep away from vibration sources, avoid resonance
  (4) Check cable joints, potting and seal for waterproofing and moisture prevention
• 4. Intermittent operation, sometimes works sometimes not, unstable fluctuation

  Core causes:
  (1) Material dust floating, sparse material intermittently contacts fork body
  (2) Electromagnetic interference: Inverter, power lines in same slot interfering with circuit
  (3) Loose installation, slight fork body wobble Troubleshooting:
  (1) Increase delay suppression, raise trigger threshold
  (2) Run signal lines in separate conduits, away from power cables, shield with single-end grounding
  (3) Reinforce flange / threaded base, eliminate looseness
• 5. Corrosion, high temperature, aging failure

  (1) High temperature over limit: exceeding rated temperature → chip attenuation, stop vibration failure
  (2) Acid/base corrosion: fork body thins, pitting, resonance frequency shifts Treatment:
  Use high-temperature specialized model for high heat, use 316L / anti-corrosion coating model for corrosion
• 6. Common human errors in electrical wiring

  (1) NO/NC normally open/normally closed reversed: alarm logic inverted
  (2) Directly driving high-power load: contacts burned and stuck Correct: control via intermediate relay isolation, do not directly drive main circuit

Malfunction and solution of rotary material level switch

• 1. First, distinguish the 2 basic normal states:

  (1) No load, no material: motor rotates normally at a uniform speed
  (2) Material blocked: blade gets stuck → stops rotating → internal micro switch activates, outputting alarm/shutdown signal
• 2. Power on but not rotating, blade not moving

  Common causes:
  
  (1) Power supply abnormal: phase loss, AC220V/DC24V voltage mismatch, loose or oxidized terminals
  (2) Internal motor burned out, reduction gear jammed
  (3) Factory-set torque too high, cannot start under no load
  (4) Main shaft or blade stuck by hardened material debris Troubleshooting: - Measure input voltage and tighten wiring - Manually rotate the blade: if it cannot rotate = mechanical jam, disassemble to clear material / replace module - Adjust torque knob lower under no load to restore normal rotation - If motor is silent and does not work: replace the motor assembly directly
• 3. Continuous rotation, with material, but no alarm, no shutdown

  High-frequency issues:
  (1) Light material (fly ash, wood powder, light calcium) has low friction, belt slips with no torque
  (2) Torque adjustment too low, resistance does not trigger micro switch
  (3) Blade size too small (standard S blade for light powders)
  (4) Shaft bushing worn, slipping under no-load Solutions:
  - Increase torque sensitivity - Replace with widened large three-blade special blade to increase force - Check main shaft clearance, replace the assembly if severely worn
• 4. Empty hopper, no material, but continuous alarms or false actions

  (1) Internal dust accumulates, gears jammed, cannot reset
  (2) Hopper vibration too large, vibrating module triggers falsely
  (3) Material clinging to main shaft forms false resistance
  (4) Internal micro switch sticking, contacts normally closed Solutions:
  - Disassemble to clean dust and remove material from shaft - Install anti-vibration base, damping - Check switch contacts, replace internal components if stuck
• 5. Frequent jamming, abnormal noise, severe vibration

  (1) Material falling directly onto blade, large pieces hitting and bending main shaft
  (2) Bearing wear, eccentric rotation grinding the housing
  (3) Incorrect vertical/angle installation, rubbing against pipe wall Solutions:
  - Install anti-collision protection tube, impact shield - Side installation at 15–20° to avoid direct drop zone - Replace if main shaft is deformed
• 6. Wiring and electrical logic faults

  (1) Normally open/normally closed reversed: alarm logic inverted
  (2) Long-term heavy load, contact erosion
  (3) Explosion-proof type sealed but water ingress or condensation short circuit Recommendation: only control intermediate relay, do not directly drive high-power load

How to install and use an ultrasonic flow meter

• I. Measurement principle and applicable contraindications

  The capacitance change between the probe and the vessel wall is used to detect the liquid level/material level Suitable for: sewage, acid and alkali, viscous slurry, powder, granules, liquid Not suitable for: pure insulation ultra-low dielectric current, serious crystallization of a large number of hanging knots, strong electromagnetic pulse interference
• II. Rigid premise of installation (whether to determine whether it is accurate or not, whether it is stable or not)

  (1) A circuit to the ground plate must be formed Metal tank: The tank is directly used as a reference ground Plastic/FRP tanks: must be installed in parallel with auxiliary grounding rods
  (2) Avoid strong interference Stay away from frequency converters, motors, heating tubes, and power cables; Signal wire shielding single-ended grounding
• III. Standard installation location

  
  (1) Side/top mounting Top mounting: the probe is vertically downwards to avoid the feed splash and blanking direct rush position Side mounting: Inserted horizontally to prevent solid impact bending Probe circumference: no tank column, stiffener, or pipe within 30cm
  (2) Key points of installation under different working conditions Liquid: Ensure no violent disturbance and no bubble accumulation Powder particles: away from the blanking port, anti-impact bending probe High temperature and high pressure: optional pressure-resistant seal and high-temperature insulation sheath
• IV. Electrode selection and installation specifications

  
  (1) Bare rod: for conductive liquids
  (2) PTFE sheath: common to acid-alkali, corrosive, and viscous media
  (3) Cable type: deep tank, large bin, powder It is strictly forbidden for the probe rod to touch the tank wall and short circuit to keep the center isolated
• V. Wiring and power supply

  (1) Power supply: DC24V/AC220V matched by model
  (2) Signal cable: shielded twisted pair wire, separate wire routing
  (3) The shell is reliably grounded, and the shield is grounded on the single-ended instrument side
  (4) The waterproof gland head is pressed, and the junction box is sealed against moisture
• VI. Commissioning steps (three key steps)

  (1) Empty tank calibration (zero point) When there is no material in the tank, empty warehouse calibration is carried out to eliminate distributed capacitance and stray signals
  (2) Full position fixed-point calibration The material submerges the probe detection section and performs high liquid level calibration
  (3) Set parameters Sensitivity Time-Delay Filtering (Anti-Fluctuation Malfunction) High and low alarm logic, normally open/normally closed output
• VII. Daily correct use judgment

  
  (1) Empty tank: normal output without liquid level and no alarm
  (2) Expected probe: reliable flipping action / analog linear rise
  (3) Stable working conditions: no drift, no frequent flash jumping
• VIII. Common faults + quick resolution

  
  (1) The empty tank has been alarming and malfunctioning Causes:
  Moisture in the hanging material, insulation decline, unempty can calibration, poor grounding Treatment:
  cleaning the probe, drying, redoing the calibration of the empty bin, improving the grounding
  (2) No testing or alarm if there is material Reasons: too low sensitivity, too short probe, high mounting position, too low dielectric Processing: Increase sensitivity, adjust insertion depth, recalibrate
  (3) Random value jumping and relay jitter Causes:
  electromagnetic interference, liquid level fluctuations, hanging drift Treatment:
  increase delay filtering, shielding isolation, and anti-hanging material cleaning
  (4) Long-term drift is inaccurate Regular self-calibration; The strong adhesion medium is made of intelligent anti-hanging RF capacitors

• I. Measurement principle and applicable contraindications

  The capacitance change between the probe and the vessel wall is used to detect the liquid level/material level Suitable for: sewage, acid and alkali, viscous slurry, powder, granules, liquid Not suitable for: pure insulation ultra-low dielectric current, serious crystallization of a large number of hanging knots, strong electromagnetic pulse interference
• II. Rigid premise of installation (whether to determine whether it is accurate or not, whether it is stable or not)

  (1) A circuit to the ground plate must be formed Metal tank: The tank is directly used as a reference ground Plastic/FRP tanks: must be installed in parallel with auxiliary grounding rods
  (2) Avoid strong interference Stay away from frequency converters, motors, heating tubes, and power cables; Signal wire shielding single-ended grounding
• III. Standard installation location

  
  (1) Side/top mounting Top mounting: the probe is vertically downwards to avoid the feed splash and blanking direct rush position Side mounting: Inserted horizontally to prevent solid impact bending Probe circumference: no tank column, stiffener, or pipe within 30cm
  (2) Key points of installation under different working conditions Liquid: Ensure no violent disturbance and no bubble accumulation Powder particles: away from the blanking port, anti-impact bending probe High temperature and high pressure: optional pressure-resistant seal and high-temperature insulation sheath
• IV. Electrode selection and installation specifications

  
  (1) Bare rod: for conductive liquids
  (2) PTFE sheath: common to acid-alkali, corrosive, and viscous media
  (3) Cable type: deep tank, large bin, powder It is strictly forbidden for the probe rod to touch the tank wall and short circuit to keep the center isolated
• V. Wiring and power supply

  (1) Power supply: DC24V/AC220V matched by model
  (2) Signal cable: shielded twisted pair wire, separate wire routing
  (3) The shell is reliably grounded, and the shield is grounded on the single-ended instrument side
  (4) The waterproof gland head is pressed, and the junction box is sealed against moisture
• VI. Commissioning steps (three key steps)

  (1) Empty tank calibration (zero point) When there is no material in the tank, empty warehouse calibration is carried out to eliminate distributed capacitance and stray signals
  (2) Full position fixed-point calibration The material submerges the probe detection section and performs high liquid level calibration
  (3) Set parameters Sensitivity Time-Delay Filtering (Anti-Fluctuation Malfunction) High and low alarm logic, normally open/normally closed output
• VII. Daily correct use judgment

  
  (1) Empty tank: normal output without liquid level and no alarm
  (2) Expected probe: reliable flipping action / analog linear rise
  (3) Stable working conditions: no drift, no frequent flash jumping
• VIII. Common faults + quick resolution

  
  (1) The empty tank has been alarming and malfunctioning Causes:
  Moisture in the hanging material, insulation decline, unempty can calibration, poor grounding Treatment:
  cleaning the probe, drying, redoing the calibration of the empty bin, improving the grounding
  (2) No testing or alarm if there is material Reasons: too low sensitivity, too short probe, high mounting position, too low dielectric Processing: Increase sensitivity, adjust insertion depth, recalibrate
  (3) Random value jumping and relay jitter Causes:
  electromagnetic interference, liquid level fluctuations, hanging drift Treatment:
  increase delay filtering, shielding isolation, and anti-hanging material cleaning
  (4) Long-term drift is inaccurate Regular self-calibration; The strong adhesion medium is made of intelligent anti-hanging RF capacitors

Malfunction and solution of rotary material level switch

• 1. Core Measurement Principle

  The probe emits ultrasonic pulses → liquid surface reflects echo → calculate the time difference to obtain the liquid level; Naturally sensitive to: foam, vapor, dust, blind spots, inclined installation, obstacles.
• 2. Essential Selection & Working Condition Confirmation Before Installation

  (1) The tank must be at atmospheric pressure, without large amounts of dense mist/vapor, and without thick foam.
  (2) Medium: Suitable for clean water, sewage, granular materials; caution with strong foaming or volatile mist.
  (3) Confirm blind zone: A distance below the probe cannot be measured (short range 0.3~0.5m, long range 1~2m).
  (4) Within measurement range: No ladders, columns, pipes, reinforcements, or stirring blades.
• 3. Standard Installation Location (Critical, Determines Accuracy)

  (1) Do not install: directly above the feed, at the center of manhole, near the tank wall, or in vortex turbulence areas.
  (2) Best position: Distance from tank wall ≥ 1/3 of tank diameter Probe perpendicular to liquid surface, strictly no tilt.
  (3) Avoid: Agitators, spray ports, material splashing, internal tank components.
  (4) Reserve high position: Ensure the minimum liquid level does not enter the blind zone. Pipeline / Pool Installation Points Pools, open channels: Away from inlet and outlet, choose calm and still water areas. Optional: Install stilling wells/diversion pipes to resist fluctuation and interference.
• 4. Mechanical Installation Standards

  (1) Flange/thread fixed securely, prevent vibration loosening.
  (2) Probe end face suspended, unobstructed, not touching dust screens, no condensate water accumulation.
  (3) Outdoor installation: Install rain and sun shields to avoid sun and rain exposure.
  (4) High-temperature tank top: Install heat-dissipating base to prevent probe chip damage due to high temperature.
• 5. Wiring and Power Supply

  (1) Power supply: DC24V preferred, check voltage for no undervoltage or voltage drop.
  (2) Signal cable shielded, single-end grounded.
  (3) Keep away from frequency converters, motors, power cables; run on separate trays to prevent electromagnetic interference.
  (4) Waterproof connectors tightened, junction boxes moisture-proof and sealed.
• 6. 5 Basic Parameters to Set at Startup (Inaccuracy if Not Set)

  (1) Range / probe measuring distance
  (2) Total tank height (empty tank height)
  (3) Blind zone suppression / near-field shielding
  (4) Filtering damping (increased liquid surface fluctuation)
  (5) False echo learning / interference suppression Setting Logic: Calibrate empty tank → shield fixed obstacle echo → match range → optimize stability.
• 7. Normal Commissioning Judgment Standards

  (1) Echo strength: value stable, strong, not flickering.
  (2) No liquid level: empty tank distance display normal.
  (3) With liquid level: follows changes smoothly, no jumps.
  (4) No false echo alarm, no lost echo.

How to install and use a gear flow meter

• 1. Understand Applicable Conditions First

  High-precision volumetric type, suitable for: lubricating oil, hydraulic oil, diesel, engine oil, resin, syrup, high-viscosity liquids Not suitable for: large amounts of bubbles, low-viscosity water, strong impurity particles, highly corrosive media
• 2. Pre-Installation Requirements (Determine Accuracy and Lifespan)

  (1) Filtration is a must (most important) Upstream configuration: 60–100 mesh filter to prevent metal shavings or impurities from jamming the gears or wearing the inner cavity
  (2) Medium conditions Must be full-pipe, single-phase liquid, no large air bubbles; bubbles cause inaccurate readings and over-measurement
  (3) Viscosity compatibility Higher viscosity results in more stable measurement; low-viscosity water has large errors and is not recommended
  (4) Pressure & Temperature Avoid overpressure, high-temperature vaporization, and negative pressure suction
• 3. Straight Pipe and Flow Direction

  (1) The arrow on the body = medium flow direction; reverse installation strictly prohibited
  (2) Normally, very long straight pipe sections are not required (advantage of volumetric type) Maintain 3D–5D upstream and downstream
  (3) Pump outlet installation: add a buffering pipe to avoid pulsating impact
• 4. Correct Installation Orientation

  (1) Oval gear / mini gear: Meter head installed horizontally, gear shaft horizontal; do not invert or install vertically
  (2) Conditions prone to gas: Install an exhaust valve at the highest point; exhaust air before startup
  (3) Inlet/outlet should avoid forced alignment; do not stress the pipes
• 5. Wiring and Signals

  (1) Pulse type: shielded twisted pair, keep away from power lines and inverters
  (2) 4-20mA type: DC24V power supply, verify polarity
  (3) Shielding layer single-ended grounding, to prevent interference and pulse spikes
• 6. Startup Steps (Must Follow Sequence)

  (1) Fully open the bypass first, slowly discharge dirt and air
  (2) Slowly open upstream and downstream valves to avoid instant high-pressure impact
  (3) Close the bypass, let the medium flow steadily
  (4) Observe: stable flow, no abnormal noise, no vibration
  (5) Set the instrument: pulse coefficient K, range, reset cumulative value
• 7. Daily Usage Precautions

  (1) Strictly prohibit dry running or running without liquid (no lubrication causes immediate wear and seizure)
  (2) Regularly clean the filter to prevent high pressure drop and insufficient supply
  (3) Prevent freezing in winter, insulate for high-temperature environments
  (4) Preheat high-viscosity media at startup to reduce resistance
• 8. Common Faults and Quick Solutions

  (1) No reading or no measurement → Impurities jamming the gears, blocked filter, dry running causing seizure; clean the filter, disassemble to remove debris, replace worn gears
  (2) Measurement too high or erratic → Air in pipeline, not vented, pump pulsing; vent at high points, add damping buffer
  (3) Measurement too low or large error → Internal gear wear, viscosity mismatch, flow below starting flow; replace the core, verify model selection
  (4) Abnormal noise or excessive vibration → Instantaneous impact, lack of lubrication, impurity collisions; open valves slowly, vent, clean filter

How to install and use an electromagnetic flow meter

• 1. Core Principles & Applicable Contraindications

  Electromagnetic flowmeters measure voltage induced as conductive liquids cut through magnetic lines of force. Can be used: water, sewage, slurry, acids and alkalis, pulp (conductivity ≥ 5 μS/cm) Cannot be used: oil, gas, steam, pure water, organic solvents (non-conductive liquids cannot be measured)
• 2. Four Mandatory Installation Conditions (most problems occur because these are not done)

  - Must ensure full pipe throughout Strictly forbid half-filled pipe, negative pressure suction, siphon venting; Inclined or vertical pipes should have fluid enter from the bottom and exit from the top to prevent gas accumulation. - Upstream and downstream straight pipe length requirements Upstream: ≥5~10D Downstream: ≥3~5D Keep away from: valves, elbows, pumps, throttling devices - Grounding is most important (exclusive for electromagnetic flowmeter) Corrosion-resistant lining pipe: must install grounding ring/grounding electrode Instrument housing and shielded cable one end properly grounded Avoid stray currents; corrosion-resistant pipe without ground return → erratic readings, drift - Avoid interference areas Keep away from inverters, high-power motors, welding machines, power cables; use separate cable trays
• 3. Correct Installation Orientation

  (1) Horizontal pipe: electrodes installed on the horizontal sides, avoid top gas accumulation and bottom sediment
  (2) Vertical pipe: fluid flows from bottom to top, ensure full pipe
  (3) Do not install at the highest point (prone to gas accumulation)
• 4. Standard Steps for Power-On and Commissioning

  - Installation inspection: flanges sealed with no leaks, grounding intact, cables secured - Ensure pipe is full of liquid, drain internal air - Power supply DC24V/AC220V, preheat 2~5 minutes - Basic parameter settings (must be set): Pipe diameter Range (maximum flow corresponds to 20mA) Empty pipe alarm, small signal cutoff Filter damping (increase if signals fluctuate) Zeroing and totalizing, check zero point: when liquid is stationary, flow display ≈ 0
• 5. Normal Usage Judgment

  (1) Stationary full pipe: instantaneous flow approaches 0, no drift
  (2) During flow: readings stable, no frequent jumps
  (3) Empty pipe triggers empty pipe alarm
  (4) 4~20mA output corresponds linearly with flow
• 6. Common High-Frequency Faults and One-Button Solutions

  (1) Pipe has water, display shows 0, no counting Conductivity too low (oil/pure water) → wrong selection, replace Electrode contamination, scaling → stop, flush and wipe electrode Excitation coil broken, mainboard fault → repair circuitry
  (2) Flow reading unstable, fluctuating greatly, drift Not grounded / poor grounding → add grounding ring, redo protective ground Liquid contains bubbles, pipe not full → vent, ensure full pipe Electromagnetic interference, power lines together → separate wiring, add isolation, increase damping
  (3) Empty pipe shows flow, zero drift Electrode damp, lining has sediment Stray potential, grounding loop → clean electrodes, recalibrate zero, improve grounding
  (4) 4-20mA output inaccurate Check range configuration, recalibrate current output; check for circuit disconnection or loose wiring
• 7. Usage and Maintenance Points

  (1) Regularly clean electrode scale, oil, and crystallization
  (2) Do not run dry or expose to gas for long periods
  (3) Avoid hard objects hitting the corrosion-resistant lining
  (4) Calibrate zero and check grounding system annually

How to install and use a capacitive level meter.

• I. Measurement principle and applicable contraindications

  The capacitance change between the probe and the vessel wall is used to detect the liquid level/material level Suitable for: sewage, acid and alkali, viscous slurry, powder, granules, liquid Not suitable for: pure insulation ultra-low dielectric current, serious crystallization of a large number of hanging knots, strong electromagnetic pulse interference
• II. Rigid premise of installation (whether to determine whether it is accurate or not, whether it is stable or not)

  (1) A circuit to the ground plate must be formed Metal tank: The tank is directly used as a reference ground Plastic/FRP tanks: must be installed in parallel with auxiliary grounding rods
  (2) Avoid strong interference Stay away from frequency converters, motors, heating tubes, and power cables; Signal wire shielding single-ended grounding
  (3) The medium cannot cover a large area and hang in the air Serious hanging, adhesion, and crystallization are easy to misjudge, so it is necessary to choose the anti-hanging and self-calibrating type
• III. Standard installation location

  (1) Side/top mounting Top mounting: the probe is vertically downwards to avoid the feed splash and blanking direct rush position Side mounting: Inserted horizontally to prevent solid impact bending Probe circumference: no tank column, stiffener, or pipe within 30cm
  (2) Key points of installation under different working conditions Liquid: Ensure no violent disturbance and no bubble accumulation Powder particles: away from the blanking port, anti-impact bending probe High temperature and high pressure: optional pressure-resistant seal and high-temperature insulation sheath
• IV. Electrode selection and installation specifications

  (1) Bare rod: for conductive liquids
  (2) PTFE sheath: common to acid-alkali, corrosive, and viscous media
  (3) Cable type: deep tank, large bin, powder It is strictly forbidden for the probe rod to touch the tank wall and short circuit to keep the center isolated
• V. Wiring and power supply

  (1) Power supply: DC24V/AC220V matched by model
  (2) Signal cable: shielded twisted pair wire, separate wire routing
  (3) The shell is reliably grounded, and the shield is grounded on the single-ended instrument side
  (4) The waterproof gland head is pressed, and the junction box is sealed against moisture
• VI. Commissioning steps (three key steps)

  (1) Empty tank calibration (zero point) When there is no material in the tank, empty warehouse calibration is carried out to eliminate distributed capacitance and stray signals
  (2) Full position fixed-point calibration The material submerges the probe detection section and performs high liquid level calibration
  (3) Set parameters Sensitivity Time-Delay Filtering (Anti-Fluctuation Malfunction) High and low alarm logic, normally open/normally closed output
• VII. Daily correct use judgment

  (1) Empty tank: normal output without liquid level and no alarm
  (2) Expected probe: reliable flipping action / analog linear rise
  (3) Stable working conditions: no drift, no frequent flash jumping
• VIII. Common faults + quick resolution

  (1) The empty tank has been alarming and malfunctioning Causes:
  Moisture in the hanging material, insulation decline, unempty can calibration, poor grounding Treatment:
  cleaning the probe, drying, redoing the calibration of the empty bin, improving the grounding
  (2) No testing or alarm if there is material Reasons: too low sensitivity, too short probe, high mounting position, too low dielectric Processing: Increase sensitivity, adjust insertion depth, recalibrate
  (3) Random value jumping and relay jitter Causes:
  electromagnetic interference, liquid level fluctuations, hanging drift Treatment:
  increase delay filtering, shielding isolation, and anti-hanging material cleaning
  (4) Long-term drift is inaccurate Regular self-calibration; The strong adhesion medium is made of intelligent anti-hanging RF capacitors

How to install and use a rotary paddle level switch.

• 1. Preparation before installation

  Check parameters: confirm the model, power supply (220VAC/24VDC/110VAC), temperature, pressure, explosion-proof level adapted to the site; Conventional power 4W, contact 5A/250VAC, blade speed 1rpm, suitable material specific gravity ≥0.5g/cm³. Inspection parts: no damage to the shell, flexible blades without deformation, no jamming of the shaft, and good sealing; Prepare a wrench, screwdriver, sealant, cable, multimeter. Safety premise: power off operation; Dust/explosion-proof environment for explosion-proof type, do a good job of grounding; The high-temperature area should be selected as a high-temperature type (-20~400°C) and add a thermal insulation pad.
• 2. Three mainstream installation methods

  (1) Horizontal installation (most commonly used, sidewall height measurement / low level) Hole positioning: select the detection height on the side wall of the silo to avoid the feeding port, mixing area, and dead corner; 20cm ≥ from the warehouse wall, reserve ≥50cm maintenance space; The upper part of the high level and the lower part of the low level (the blades are 10~15cm from the bottom of the warehouse). Fixed base: welded/flanged fixed mount to ensure firmness; When installed horizontally, the overall inclination is 15°~20°, and the junction box inlet is vertically facing down (to prevent water and dust). Install blades and shafts: connect the drive shaft and blades to ensure that the level is not skewed and the rotation is smooth; The blade extension depth should be just enough to cover the material, avoid too deep/too shallow. Anti-impact: add a protective baffle near the feeding port to protect the blades and reduce mismovement.
  (2) Vertical installation (top / bottom of the bin, full bin / empty bin) Silo roof installation (high / full): vertically downward from the silo roof, blades facing down; 1/6 of the silo diameter ≥ the silo wall to avoid side wall accumulation interference; The blades are vertical and not deflected, preventing deformation under force on one side. Bottom of the bin (low / empty): loaded from the bottom up, blades facing up; 10~15cm from the bottom of the silo to prevent residual jamming; It is only suitable for materials with good fluidity and no agglomeration.
  (3) Inclined side wall installation (adapted to inclined silos) The blade is perpendicular to the natural accumulation surface of the material (usually 45°~60° horizontally) to avoid the material sliding over without triggering; Installed at the same level, the inlet is facing down and sealed.
• 3. Wiring steps (safety first)

  Open the junction box: Unscrew the box cover and confirm the terminal identification (power supply L/N, common COM, normally open NO, normally closed NC). Wiring specifications: Power supply: connect to the corresponding voltage (such as 220VAC to L/N, 24VDC to positive and negative poles); Signal: COM is connected to the common end, NO/NC is connected to the control loop (NO for full bins, NC for empty bins); Sealing: the cable is threaded through the sealing joint, the lock nut, and the waterproof bend is left in the box; The inlet is facing down, the box lid is tightened, and waterproof glue must be added. Power-on test: use a multimeter to measure the on/off after wiring; The no-load blade rotates at a constant speed (1rpm), stops when the material is encountered, and the contact switches are qualified.
• 4. Key debugging (determine accuracy)

  Torque Adjustment (Core): Heavy/high-density materials (such as ores, granules): increase torque (anti-jamming, protect motor); Light/low-density materials (such as dust, powder): reduce torque (improve sensitivity, prevent mismovement); Method: Open the upper cover, tighten the adjustment screw (increase clockwise, decrease counterclockwise), subject to "stop when the material is encountered, turn when the material goes". Sensitivity calibration: no-load rotation, stop when the material is encountered; When loaded at a high level, the blades are expected to stop; When loaded low, the material rotates when it is lower than the blade.
• 5. Daily use and maintenance (extended life)

  (1) Normal use Power on: automatic rotation when powered on, no need to manually start and stop; Signal: Full warehouse stop → contact action (alarm / stop); Automatic reset → material drop; Contraindications: No over-temperature/overpressure, no hard objects hitting the blades, no strong corrosive environment (choose anti-corrosion type).
  (2) Regular maintenance (once a month) Power-off and clear blades: Clear the adhesive / agglometry in time to prevent mismovement; Check the seal: the junction box and shaft seal are free of water and dust, and they will be replaced when they are aged; Measured torque: loose / readjusted when sensitivity decreases; Check the wiring: the terminals are not loose or oxidized; Explosion-proof area: check the grounding and sealing according to the specifications, and private demolition is prohibited.

How to install and use a tuning fork level switch.

• 1. Preparation before installation (must-do)

  (1) Parameter verification: confirm the model, power supply (220VAC/24VDC), temperature (-40~150°C), pressure, explosion-proof/anti-corrosion adaptation; The tuning fork has an inherent frequency of about 1200Hz, an action hysteresis of ≤1s, and a contact capacity of 5A/250VAC.
  (2) Component inspection: no deformation, no cracks, vibration and crispness of the fork body; The junction box is intact and the seals are complete; Prepare wrenches, raw material tape/sealant, multimeter, and insulating tape.
  (3) Safety premise: power off operation; explosion-proof type and reliable grounding in the explosion-proof area; Select the corresponding specifications in the high-temperature/high-pressure area and reserve the maintenance space.
• 2. Three major installation methods (core + taboo)

  (1) Vertical installation (most stable, suitable for high viscosity/block/powder) Silo top loading (high / full): the fork end is vertically downward, 1/3 of the container radius ≥ the silo wall; avoid the impact of the feeding port, mixing area, and blanking; The fork body does not touch the inner wall/component; It is strictly forbidden to fork upwards. Bottom of the bin (low/short): the fork end is up (only the low position is available), 10~15cm from the bottom of the bin; Anti-accumulation jam forks, suitable for materials with good fluidity.
  (2) Horizontal installation (commonly used on side walls, measured in the middle and low levels) The fork body is horizontal, the two forks are the same height, and the whole is inclined downwards by 15°~20° (anti-hanging, easy to dematerialize); Away from the feeding port (horizontal distance ≥ fork length 2 times), a protective baffle must be added; The fork body extends 50~100mm without hitting the wall.
  (3) Tilt installation (suitable for inclined bin / easy to hang) The fork end is tilted downwards by 15°~20°, perpendicular to the material accumulation surface; High viscosity/strong hanging material is preferentially vertically downward, eliminating horizontal/upside loading.
  (4) Mounting and fixing (thread / flange) Thread installation (small diameter / low pressure): the interface is wrapped around the raw material belt (clockwise), and the wrench is gently twisted 1~2 turns after being screwed in place by hand; Junction box inlet facing down (water and dust resistant). Flange installation (large tank / high pressure): flange matches the pressure level, put temperature resistance/anti-corrosion gasket; Diagonal uniform fastening, anti-deflection; The sealing surface is free of impurities and scratches.
  (5) Absolute taboos The fork end is loaded upwards (stacking, mismovement, jamming fork); loading inlet / blanking area / mixing side; Fork body hits the wall / welding slag / hard objects; The seal is not tight, water and dust are ingress.
• 3. Wiring steps (minimalist, no debugging)

  (1) Open the box to recognize the terminals: L/N (power), COM (public), NO (normally open), NC (normally closed); Indicator lights: no-load flash (normal vibration), submerged solid (action).
  (2) Standardized wiring: Power supply: 220VAC to L/N; 24VDC with positive and negative electrodes (non-polarity); Signal: COM connection loop, NO for full position, NC for short position; Sealing: the cable is threaded through the waterproof joint, locked, and the waterproof bend is left in the box; The inlet is facing down, the box lid is tightened, and sealant is added.
  (3) Power-on self-test: no-load indicator flashes (normal vibration); Hand pinching fork body (simulated material) → light is always on, contact switching; If you let go→ flash again, normal is qualified.
• 4. Use and debugging (almost free of adjustment)

  (1) Normal operation: it works when the power is turned on, no need to start and stop manually; Expect the fork body to stop vibration → contact action (alarm / stop); Automatic reset → material drop.
  (2) Sensitivity (rarely adjusted): Conventional: factory default (highest), suitable for most working conditions; High viscosity / easy to hang: reduce sensitivity (anti-malfunction); Light powder / low density: keep high sensitivity; No mechanical adjustment, fully electronic adaptation.
  (3) Delay setting (optional): some models have 0~10s delay to prevent fluctuation false alarms; The stable working condition is set to 0s, and the fluctuation is set to 2~5s.
• 5. Daily maintenance (super simple)

  (1) Regular inspection (once a month): power off and clear the body of the adhesive/agglomeration; check that the seal and wiring are not loose; Look at the indicator status.
  (2) Long-term suspension: power off, fork clearing, dry storage; Anti-corrosion and anti-deformation.
  (3) Explosion-proof area: check the grounding and sealing according to the specifications, and private demolition is prohibited.

How to install and use a pressure transmitter.

• 1. Brief Introduction to Working Principle

  The pressure medium is transmitted through the isolation diaphragm and filled silicone oil to the diffused silicon/single crystal silicon sensing element, converting it into a standard electrical signal: conventional output: 4–20mA DC, corresponding to the lower to upper range.
• 2. Pre-Installation Inspection and Model Confirmation

  (1) Verification: range, medium compatibility, temperature, explosion protection, protection level, power supply (conventional 24VDC)
  (2) Appearance: diaphragm free from dents, threads/flanges intact, junction box seal undamaged
  (3) Accessories: valve assembly (two-valve/three-valve assembly), condensation ring, impulse tube, sealing gasket, PTFE tape Prohibitions Before Installation Strictly prohibit over-range pressurization, poking the diaphragm with hard objects, direct high-temperature medium impact on the diaphragm, and negative pressure exceeding vacuum rating.
• 3. On-Site Installation Specifications

  (1) Pressure Tap Opening Location Gas measurement: tap the upper part of the pipeline to prevent liquid accumulation from entering the transmitter Liquid measurement: 45° below the horizontal centerline of the pipeline to prevent gas accumulation Steam measurement: same as liquid position, must install a condensation bend/condensation container
  (2) Impulse Tube Laying Short, straight, few elbows, slope ≥1:10 Liquid: inclined toward the transmitter to facilitate air release Gas: inclined toward the pressure tap to facilitate liquid discharge Steam: pre-fill condensation tube with condensate to protect high-temperature diaphragm
  (3) Transmitter Body Installation and Fixing Away from vibration, strong electromagnetic interference, and high-temperature heat sources Local installation height: convenient for reading and calibration (1.2–1.6m) Threaded installation: apply PTFE tape, ensure sealing, do not forcefully tighten the housing Flange/diaphragm sealing: center the gasket, evenly tighten diagonally to prevent diaphragm damage due to uneven pressure
  (4) Standard Installation of Three-Valve/Two-Valve Assembly (commonly used for differential/ gauge pressure) Start-up sequence: open balance valve → open high-pressure valve → open low-pressure valve → close balance valve Shutdown depressurization: open balance valve first → close high and low-pressure valves → release pressure slowly Prevents one-way overpressure from damaging the sensor
• 4. Electrical Wiring

  (1) Power supply: standard DC 24V
  (2) Two-wire system: power supply and signal share the same line; even simple models without polarity distinction should follow the markings
  (3) Shielded cable: ground the shield at one end only (control room side, not on-site, to prevent interference)
  (4) Junction box: tightly secure waterproof cable glands, outlet facing downward to prevent moisture and dust
  (5) Explosion-proof applications: sealed cable gland and explosion-proof surface must not be impacted, never open cover with power on
• 5. Commissioning and Zero/Span Adjustment

  (1) Before gas/pressure connection: ensure pipeline has no leaks and valve positions are correct
  (2) Static zero calibration When at atmospheric pressure and no applied pressure, the display should read 0; make slight zero adjustment if necessary (local buttons/handheld terminal)
  (3) Span confirmation Apply full-scale pressure, output should correspond: 4mA (zero)–20mA (full scale)
  (4) Transfer adjustment For liquid level and negative pressure applications, perform positive and negative transfer to compensate for static pressure according to installation height
• 6. Daily Use and Maintenance Points

  (1) Regularly check the impulse tube for blockage, leakage, and condensation level
  (2) For viscous or crystalline media: use diaphragm seal and flush regularly
  (3) Do not disassemble under pressure; release pressure completely before disassembly
  (4) Winter insulation and heating to prevent impulse tube from freezing

How to install and use a turbine flow meter.

• I. Measurement Principle

  The fluid impacts the impeller causing it to rotate, and the rotational speed is proportional to the volumetric flow. A magnetic induction detects pulse signals, which are converted into 4–20mA / frequency outputs; the accuracy is high and the response is fast, suitable for clean liquids / gases. Common applications: clean water, diesel, lubricating oil, methanol; avoid impurities, air bubbles, and water hammer impact.
• II. Verification Before Installation

  (1) Check: diameter, medium (liquid / gas), range, pressure rating, temperature, explosion-proof status, pulse / 4–20mA output.
  (2) Accessories: filter (required), straight pipe sections, check valve, drain valve, sealing gaskets. Prohibitions: Strictly forbid the presence of particulate impurities, fibers, large air bubbles, instantaneous water hammer, and over-range impact.
• III. Rigid Pipe Installation Requirements

  (1) Standard straight pipe section: Upstream ≥10D, downstream ≥5D If there is an elbow, valve, or reducer at the front end: increase upstream to 15–20D.
  (2) Flow direction and installation orientation: Liquid turbine: preferably installed horizontally, with the nameplate facing up. Do not install upside down or at a large tilt; ensure the pipe is full of liquid with no bubbles. Gas turbine: can be horizontal / vertical, gas must be dry with no droplets to prevent impeller from sticking.
  (3) Standard pre-protection (mandatory): Install a Y-type filter upstream to prevent sand and iron chips from blocking the impeller. For pipelines prone to water hammer, install buffer, pressure-stabilizing, and check valves at the front end. Newly installed pipelines must be flushed first, bypass and drain sewage; debris must not flow directly into the meter.
  (4) Sealing and stress considerations: Align flanges / threaded connections, tighten diagonally and evenly; the meter must not bear mechanical tension or torque from the pipeline.
• IV. Electrical Wiring

  Power supply: DC24V; pulse type passive / active output. Shielded signal wires should be laid separately, away from power cables and inverters. Explosion-proof type: seal gland must be tightened; never open the cover with power on, ensure reliable grounding. Junction box outlet should face down, waterproof and moisture-proof.
• V. Start-up and Test Procedure

  (1) First open the bypass and fully open upstream and downstream valves, flush the pipeline to remove debris and air.
  (2) Slowly open the valves before and after the flow meter, gradually increase pressure, avoid rapid opening / closing to prevent water hammer.
  (3) Confirm: pipe is full of liquid, no negative pressure, no abnormal noise, impeller rotates smoothly.
  (4) Parameter settings: pulse coefficient K value corresponding to the measurement range, reset totalizer, apply filter to prevent jitter.
• VI. Daily Proper Use

  (1) Maintain full pipe and stable pressure operation over long periods.
  (2) Regularly drain and clean the filter to prevent blockage causing flow deficiency or meter jamming.
  (3) Strictly forbid exceeding instantaneous flow rate or reverse flow.
  (4) In winter, prevent freezing; for cooling mediums, prevent solidification that may jam the impeller.

How to install and use a vortex flow meter.

• I. Measurement Principle

  The fluid impacts the impeller causing it to rotate, and the rotational speed is proportional to the volumetric flow. A magnetic induction detects pulse signals, which are converted into 4–20mA / frequency outputs; the accuracy is high and the response is fast, suitable for clean liquids / gases. Common applications: clean water, diesel, lubricating oil, methanol; avoid impurities, air bubbles, and water hammer impact.
• II. Verification Before Installation

  (1) Check: diameter, medium (liquid / gas), range, pressure rating, temperature, explosion-proof status, pulse / 4–20mA output.
  (2) Accessories: filter (required), straight pipe sections, check valve, drain valve, sealing gaskets. Prohibitions: Strictly forbid the presence of particulate impurities, fibers, large air bubbles, instantaneous water hammer, and over-range impact.
• III. Rigid Pipe Installation Requirements

  (1) Standard straight pipe section: Upstream ≥10D, downstream ≥5D If there is an elbow, valve, or reducer at the front end: increase upstream to 15–20D.
  (2) Flow direction and installation orientation: Liquid turbine: preferably installed horizontally, with the nameplate facing up. Do not install upside down or at a large tilt; ensure the pipe is full of liquid with no bubbles. Gas turbine: can be horizontal / vertical, gas must be dry with no droplets to prevent impeller from sticking.
  (3) Standard pre-protection (mandatory): Install a Y-type filter upstream to prevent sand and iron chips from blocking the impeller. For pipelines prone to water hammer, install buffer, pressure-stabilizing, and check valves at the front end. Newly installed pipelines must be flushed first, bypass and drain sewage; debris must not flow directly into the meter.
  (4) Sealing and stress considerations: Align flanges / threaded connections, tighten diagonally and evenly; the meter must not bear mechanical tension or torque from the pipeline.
• IV. Electrical Wiring

  Power supply: DC24V; pulse type passive / active output. Shielded signal wires should be laid separately, away from power cables and inverters. Explosion-proof type: seal gland must be tightened; never open the cover with power on, ensure reliable grounding. Junction box outlet should face down, waterproof and moisture-proof.
• V. Start-up and Test Procedure

  (1) First open the bypass and fully open upstream and downstream valves, flush the pipeline to remove debris and air.
  (2) Slowly open the valves before and after the flow meter, gradually increase pressure, avoid rapid opening / closing to prevent water hammer.
  (3) Confirm: pipe is full of liquid, no negative pressure, no abnormal noise, impeller rotates smoothly.
  (4) Parameter settings: pulse coefficient K value corresponding to the measurement range, reset totalizer, apply filter to prevent jitter.
• VI. Startup Procedure

  (1) First bypass to flush the pipeline, remove welding slag and debris.
  (2) Open and close valves slowly; abrupt opening or closing is strictly prohibited to prevent impact and oscillation.
  (3) Vent completely, ensure the pipeline is full of liquid, pressure is stable, and there is no pulsation.
  (4) Parameter settings: instrument K factor, range, filtering time, medium density; use temperature and pressure compensation model for steam.
  (5) Observation: flow rate is stable without sudden changes, no abnormal whistling or vibration.
• VII. Daily Use and Maintenance

  (1) No moving parts, basically maintenance-free.
  (2) Regular inspection: if deposits form on the device or pipeline walls are dirty, stop operation and perform purging and cleaning.
  (3) Insulate and heat steam pipelines to prevent condensate from flooding the probe.
  (4) Avoid long-term operation beyond the range or at very low flow rates (below the lower limit will result in no measurement).

How to install and use a temperature transmitter.

• I. Working Principle

  Field thermocouple / RTD signal → Linear isolation conversion within the transmitter circuitry → Standard DC 4–20 mA output; Types: integrated rail-mounted, head-mounted, anti-interference, long-distance transmission, PLC compatible.
• II. Pre-Installation Checklist

  Input type: PT100, K, J, E, S Range, power supply DC 24V, output 4–20 mA, isolated / non-isolated Protection level, explosion-proof, environmental temperature and humidity Taboos: mixing thermocouples with ordinary copper wires, using PT100 without three-wire configuration, directly baking the housing at high temperature, installing near strong electromagnetic fields.
• III. Sensor Field Installation (Preliminary Requirements)

  Insert the temperature probe according to specifications: 1/3–1/2 of the pipe diameter for liquids/pipes Prefer three-wire RTD to eliminate lead resistance error Thermocouples must use dedicated compensation wires, match the type number, and distinguish positive and negative poles Keep the probe away from erosion, vibration, and corrosion, and ensure it is sealed and waterproof
• IV. Main Temperature Transmitter Installation

  (1) Head-mounted installation (integrated on-site) Directly mount in the RTD / thermocouple junction box: Ensure ventilation, away from high-temperature pipe walls (prevent housing overheating and drift) Install waterproof gasket, tighten junction box cover
  (2) Rail-mounted installation (inside control cabinet) Standard DIN rail snap installation, secure and stable Keep away from contactors, inverters, high-power relays (to prevent interference) Ensure ventilation inside the cabinet to prevent heat accumulation
• V. Standard Wiring (Common Error Points)

  (1) RTD input (PT100) Three-wire: two same-colored, one different color, strictly match terminals Long two-wire usage is prohibited due to large error
  (2) Thermocouple input Distinguish positive and negative poles, only use matching compensation wires Prohibit extending with ordinary copper wires or mixing hot and cold ends at high temperature
  (3) Power and output Power supply: DC 24V Two-wire: power and 4–20 mA signal share the same circuit Shielded cable grounded at one end (control room side), do not run in the same conduit with power cables
• VI. Range Setting and Debugging

  Set according to process: lower limit → 4 mA, upper limit → 20 mA Check at ambient temperature with no load: display shows normal environment temperature Zero fine-tuning: slightly adjust on-site at ambient temperature Damping filter: increase 1–5 s for large fluctuations to prevent jumping Enable cold junction compensation in thermocouple applications
• VII. Routine Use and Maintenance

  XXX
• Tighten terminals regularly to prevent oxidation and loose connection Check probe protective tube for corrosion, scaling, and damage Outdoor locations should be moisture-proof and waterproof; never open covers in explosive areas while powered Calibrate zero and full scale annually

  XXX

How to install and use a submersible level meter.

• 1. Measurement principle

  Using liquid static pressure = liquid column height × density × gravity acceleration, the diaphragm at the bottom of the probe feels the pressure, and converts it into a standard signal of 4~20mA to directly display the liquid level. It comes with a ventilation guide cable, which automatically compensates for atmospheric pressure and does not need to be connected to a separate negative pressure pipe. Applicable: pool, water tank, sewage, tank atmospheric pressure level, cost-effective, simple installation.
• 2. Check before installation

  (1) Range selection: the actual height of the liquid level ×1.15 margin selection to avoid overpressure
  (2) Material: 304/316L, PTFE anti-corrosion (sewage, acid and alkali)
  (3) Power supply: DC24V, output 4–20mA, protection IP68
  (4) Inspection: no bumps in the probe diaphragm, no bending and breaking of the gas guide cable, complete counterweight, and filter anti-blocking cap Contraindications: It is strictly forbidden to poke the pressure-sensitive diaphragm, water inlet of the cable vent, strong acid and alkali are not suitable for anti-corrosion, and sediment directly siltation to block the probe.
• 3. Correct installation on site

  (1) Probe placement position Open Pool / Water Tank: Avoid direct water flushing, stirring vortex, and backwater outlet Stay away from the pool wall to prevent measurement inaccuracies caused by adherence to the wall Reserve 100~200mm suspension at the bottom, and do not directly sink the bottom anti-silt plugging diaphragm Closed atmospheric pressure tank: vertically lowered from the top reserved port to ensure free vertical, no winding, and no squeezing
  (2) Fixing of installation accessories Counterweight hammer / lower hanging counterweight: ensure vertical straightening and no floating and skewing Upper cable fixing card: shock absorption, anti-pulling, do not tighten the breathable core Sewage easy to block media: install anti-siltation and water filtration shields
  (3) Key protection of gas conductive cables The whole cable is strictly prohibited from being soaked in water and sealed with hot melt The upper ventilation section must be ventilated, dry, and not waterlogged The curvature of the wiring is reserved, and it is strictly forbidden to break hard, crush, and scratch sharply
• 4. Electrical wiring specifications

  (1) Two-wire system: DC24V power supply 4–20mA signal is shared
  (2) Distinguish between positive and negative, and connect to the corresponding circuit of PLC/digital display
  (3) Shielded cable: the control room is grounded at one end, away from the frequency converter and motor power cable
  (4) Junction box: the waterproof connector is locked, and the outlet line is facing downwards to prevent condensation and water ingress
• 5. Commissioning and calibration

  (1) No-load inspection: the probe is suspended without water, the instrument shows the liquid level ≈0, and the slight deviation is cleared at zero
  (2) Water entry test: slowly put it into the water, the liquid level rises with it, 4mA corresponds to the empty tank, 20mA corresponds to the full scale
  (3) Parameter setting Set range height and damping filter (sewage fluctuation is increased by 2~5s) Density correction: Acid-base/heavy oil fine-tuned according to the actual density
• 6. Daily use and maintenance

  (1) Regular lifting and cleaning: the silt and debris wrapped in the bottom will drift at zero point
  (2) Check the breathable cable: no water ingress, no aging, no pulling and breaking
  (3) Anti-freezing in winter: the shallow pool should be kept warm to prevent the probe from freezing and damaging the diaphragm
  (4) Anti-corrosion working conditions: regularly check the corrosion of the probe shell and replace the anti-corrosion model

How to install and use a RF admittance level switch.

• 1. Working Principle

  Utilizes high-frequency RF bridge to detect capacitance/impedance, distinguishing between pure capacitance, material adhesion, and material coverage; Compared with ordinary capacitive switches: resistant to adhesion, prevents false triggering due to hanging material, dust and crystallization resistant, suitable for granular material, powder, slurry, and viscous material.
• 2. Pre-Installation Checks

  (1) Verify: power supply (220VAC/24VDC), explosion-proof, corrosion-proof, rod/cable/flat probe, high temperature and pressure rating, relay contact NO/NC
  (2) Appearance: probe insulation intact, no cracks, junction box properly sealed
  (3) Applicability: coal powder, plastic granules, chemical powder, sewage sludge, viscous slurry Prohibitions: strong corrosion not lined with PTFE, probe bumps and scratches, direct metal contact with tank causing short circuit
• 3. On-Site Installation Standards

  (1) Installation Location Selection High-level full material alarm (vertically installed on top of the silo): The probe points vertically downward, away from feed dropping impact areas, agitator blades, and internal columns Distance from the silo wall ≥ 300mm to avoid false triggers from sidewall accumulation Cable-type long probes must not be pulled tight; leave some sag Sidewall mid-to-low-level detection (horizontal side-mount): Probe slightly tilted downward 10–15° Facilitates material sliding off, reduces adhesion, prevents false alarms Avoid vortices and direct material impact; install protective baffles if necessary Liquid / viscous slurry: Use PTFE-lined corrosion-resistant probe to prevent corrosion and short-circuit from scaling
  (2) Installation Fixing Method Thread installation: use PTFE gasket/copper sealing washer, avoid forcing the probe by hand Flange installation: tighten diagonally and evenly, ensure insulation areas are not pressed Internal metal components: keep probe insulated from tank, strictly avoid contact with metal
  (3) Key Insulation Requirements The middle insulated section of the probe must be intact, must not touch the tank wall or accumulate conductive moisture or dirt, otherwise, it will cause permanent false operation
• 4. Electrical Wiring

  (1) Power: AC 220V or DC 24V, distinguish AC and DC and do not connect randomly
  (2) Output relay: COM common, NO normally open, NC normally closed Full material shutdown/alarm: normally use NC
  (3) Shielded cable should be routed separately, away from inverters and motor power lines
  (4) Explosion-proof type: never open cover under power, tighten sealing glands securely, reliable grounding required
• 5. On-Site Commissioning and Calibration

  (1) Empty Tank Zero Calibration With no material in the tank and probe clean and dry, perform empty tank calibration to eliminate hanger material and distributed capacitance baseline
  (2) Actual Material Sensitivity Adjustment Dry powder, low-density material: increase sensitivity Wet, viscous, or easily adhering material: reduce sensitivity and increase delay Some models have anti-adhesion and delay filtering DIP switches, set as needed Normal logic: Material not touching probe → output normal state; material covering probe → relay toggles, alarm/interlock
• 6. Correct Daily Use & Maintenance

  (1) Advantages: built-in anti-adhesion circuit, slight adhesion does not trigger false operation
  (2) Regular shutdown inspection: clean probe from scaling, clumping, and conductive moisture or dirt in time
  (3) High-temperature condensation conditions: strengthen insulation and moisture protection to prevent insulation drift
  (4) Cable-type probes: regularly check for slack, wear, and short-circuit risks

How to install and use a thermal gas flow meter.

• 1. Measurement principle

  Built-in two platinum resistors: temperature measurement probe + heating probe, constant temperature difference control; The larger the gas flow rate, the more heat is taken away, and the heating power is proportional to the mass flow rate of the gas. Advantages: direct standard volume/mass flow, no need for temperature and pressure compensation, low flow rate sensitivity, small pressure loss Disadvantages: Afraid of frequent changes in oil and water, dust, condensation, and gas components
• 2. Pre-installation verification

  (1) Distinguish types Pipe section type: DN15~DN200, small diameter, high precision Plug-in type: DN80 or above large ducts, air ducts, flues, easy to install
  (2) Confirm parameters: medium, explosion-proof, temperature and pressure, power supply 24VDC, 4-20mA/pulse/RS485
  (3) Contraindications under working conditions It is strictly forbidden to contain water mist, oil stains, liquid condensate, and a large amount of dust; Easy fouling can lead to probe packaging, zero drift, and measurement failure.
• 3. Core installation specifications

  (1) Requirements for straight pipe sections (rigid standards) Upstream: ≥15D straight pipe section Downstream: ≥5D straight pipe section Elbows, valves, reducers, and fan outlets must reserve enough straight pipe sections, otherwise the eddy current turbulence error will be large.
  (2) Hole opening and installation position Horizontal pipes: preferentially installed on the side of the pipe 30°~45°: avoid dust accumulation at the top and liquid accumulation at the bottom Vertical pipeline: gas flow from bottom to top is the best; It is easy to return from top to bottom, and the metering is inaccurate Air ducts/chimneys: Away from wind deflectors, inflection points, turbulent areas at the outlet of fans
  (3) Insertion depth (top priority) Standard: The probe center is located at the center point of the pipe flow rate Conventional large pipe: insert 1/2 of the radius of the pipe Plug-in type with ball valve: installation / disassembly with non-stop air pressure, close the ball valve first and then pull out the probe
  (4) Fixing and sealing Thread / base is equipped with gaskets and raw material belts to fasten to prevent air leakage High temperature and high pressure, explosion-proof places: the sealing gland is pressed, and the explosion-proof box is strictly prohibited from opening the lid with electricity Vibration pipeline: Shock absorbing bracket is installed to avoid fatigue and fracture of the probe
• 4. Electrical wiring

  Power supply: DC24V conventional two-wire / four-wire system Signal: 4-20mA, pulse, Modbus/HART correspond to terminal identification Shielded cable: separate routing, not co-piped with power cable; Shielded control room single-ended grounding anti-interference Junction box: Waterproof connector locked, outlet downward to prevent rain and dust
• 5. On-site commissioning and commissioning

  (1) Preventilation examination There is no leakage in the pipeline, the probe is clean and free of oil and dust, and the installation depth is correct
  (2) Static zero point calibration (the most critical) When the pipeline has no gas flow and is closed and stationary, one-key zero-point calibration is performed; If you don't do zero points, the small traffic is seriously inaccurate
  (3) Parameter setting Set medium type: air / nitrogen / natural gas / argon gas, etc Standard unit: Nm³/h, kg/h Filter damping: Increase damping under turbulent flow conditions to avoid numerical runout
• 6. Key points for correct daily use

  (1) It is suitable for drying and cleaning single-component gases
  (2) It is forbidden to overload and large flow for a long time
  (3) Avoid frequent start and stop and sharp pressure fluctuations
  (4) Component changes (gas mixing, purity fluctuations) need to be recalibrated and corrected
• 7. Maintenance

  (1) Periodic dust cleaning: Under dust conditions, the double probe is purged with compressed air every month
  (2) Oil and scale are found: stop the machine and disassemble it with alcohol to clean and dry and reset
  (3) In the rainy season, low temperature to prevent pipeline condensation and prevent the probe from getting water
  (4) Compare and verify the zero point and the range once a year

How to install and use a thermal resistance.

• 1. Basic Principle

  Temperature measurement is conducted using the principle that the resistance of a metal conductor increases with temperature. Common types include: PT100 (0℃ = 100Ω, commonly used in industry, -200 to 550℃); PT1000, which has higher accuracy. Difference from thermocouples: passive resistance signal, precise at low temperatures, no compensation wiring needed.
• 2. Pre-Installation Check

  (1) Model: PT100 / PT1000, protection level, explosion-proof, corrosion-resistant, wear-resistant, armored
  (2) Lead type: three-wire (mainstream on site, offsets lead resistance errors), two-wire, four-wire
  (3) Protective tube: 304/316L stainless steel, alumina, PTFE corrosion-resistant Do not forcibly bend armored wires, hit the sensing end of the probe, exceed temperature or pressure limits, or use long two-wire leads (prone to error).
• 3. Core Installation Standards

  (1) Insertion Depth (Critical) For pipeline liquids/gases: insert 1/3 to 1/2 of pipe diameter For air ducts, flues, tanks: exposed sensing length ≥ 80–120mm Shallow installation: lower measured temperature, greater lag, out-of-spec errors
  (2) Installation Orientation: Horizontal process pipelines: insert at a 45° inclined angle from above to avoid gas layers at the top and sediment at the bottom High-temperature furnaces/boxes: sidewall horizontal installation preferred to reduce radiative heat loss from the top Flowing media: install facing the flow direction for faster heat exchange and more accurate response
  (3) Fixing and Sealing Threaded installation: use high-temperature gasket / copper gasket for sealing, do not forcibly tighten the sheath Flange installation: tighten evenly in diagonal sequence, center the gasket to prevent leaks Vibrating equipment: use anti-vibration armored probes with bracket fixation to prevent core wire breakage Corrosive/wastewater environments: use PTFE-sleeved protective tube or integrated corrosion-resistant type
• 4. Wiring Methods

  (1) Three-wire (engineering preferred) Two same-colored wires (resistance compensation), one single-colored wire connected to the corresponding terminal on the instrument to eliminate measurement deviations caused by lead resistance.
  (2) Two-wire Suitable only for short distances with low-temperature requirements; long lines cause significant errors.
  (3) Four-wire Used in precision labs / metrology to completely eliminate lead resistance.
  (4) General wiring requirements Do not lay with power cables in the same conduit to avoid interference Shielded cables: connect one end to ground Terminal crimping should be firm to prevent oxidation and loose connections causing count errors
• 5. Commissioning

  (1) Power on at room temperature: a reading close to ambient temperature is normal
  (2) Hold the sensing probe by hand: temperature rises steadily, indicating the circuit is intact
  (3) Instrument parameters: select corresponding PT100 scale and three-wire mode
  (4) Minor deviations: fine-zero calibration inside the instrument
• 6. Routine Maintenance

  (1) Regularly check the protective tube for scaling, corrosion, deformation, leaks
  (2) Tighten wiring terminals, clean oxidation and dust
  (3) In winter, insulate and provide heat trace for outdoor installations to prevent frost affecting measurement
  (4) Replace wear-resistant protective sleeves regularly in high-wear conditions

How to install and use a thermocouple.

• I. Basic Principle

  Two different metal conductors are welded at one end (hot end / measuring end), while the other end serves as the cold junction. The temperature difference generates thermoelectric potential, which is converted into a temperature signal. Use with a matching display meter / temperature controller and compensating wires; commonly used types are K, J, E, S, PT100 (platinum resistance thermometers are treated separately).
• II. Pre-Installation Check

  Graduation type: K (general-purpose - 200~1300℃), S (high-temperature precious metal), J (medium-temperature iron-constantan) Protective tube material: stainless steel, 316L, corundum ceramic tube (high temperature) Structure: assembled, armored, threaded / flange-fixed, corrosion-resistant / explosion-proof selection Accessories: compensating wires, cold junction compensated instruments, sealing gaskets, insulation cotton Prohibitions: Do not use at over-temperature for long periods, do not bend armored rigid tubes, do not damage temperature measurement welding points, reversing polarity causes large measurement error.
• III. On-Site Standard Installation

  (1) Insertion Depth (core key) Liquid / Pipe: insert 1/3~1/2 of the pipe diameter Hot air / flue / furnace: ≥100~150mm Storage tanks: avoid dead corners, close to key process temperature measurement points Too shallow: low temperature reading, slow response; too deep: may damage protective tube
  (2) Installation Orientation Fluid pipe Horizontal pipe: insert at a 45° angle from above to avoid bottom sediment and top gas layer High-temperature furnace / box Vertical downward or sidewall horizontal installation, strictly forbid top insertion into large radiation areas High pressure / pressure-bearing equipment Use flange and tight threaded sealing, test for no leakage; high-temperature and high-pressure sheath
  (3) Fixing and Sealing Threaded installation: wrap with high-temperature raw tape / metal gasket, tighten without excessive force Flange installation: tighten evenly diagonally, gasket centered Vibrating equipment: use anti-vibration armored thermocouples, add fixed brackets to prevent breakage
  (4) Protective Options Corrosive media: PTFE sheath, corrosion-resistant stainless steel Dust furnace: wear-resistant protective tube Explosion-proof area: explosion-proof seal junction box, no exposed wiring
• IV. Compensating Wire Connection

  (1) Distinguish positive and negative poles, color-coded by type: K-type compensating wire conventionally: green positive, white negative
  (2) Fully match type, do not mix, do not replace with ordinary copper wire
  (3) Cold junction wiring away from high-temperature area, centralized in instrument cabinet at room temperature
  (4) Shielded cables: shield layer grounded at one end, resistant to electromagnetic interference
  (5) When instruments are powered on: cold junction temperature automatic compensation
• V. Commissioning and Calibration

  (1) Power-on check: shows ambient temperature when no measurement, normal
  (2) Heating verification: apply heat to hot end, temperature rises synchronously
  (3) Error correction: small on-site deviation, fine-tune range on instrument
  (4) Prohibitions: do not short-circuit thermocouple to simulate temperature, do not arbitrarily extend ordinary wires
• VI. Routine Use and Maintenance

  (1) Regularly inspect protective tube: corrosion, cracking, deformation, carbon deposition
  (2) High-temperature operation: periodically check aging, thermoelectric performance drift
  (3) Tighten wiring terminals, prevent oxidation and poor contact
  (4) Insulate well outdoors in winter to avoid cold junction temperature fluctuations

How to install and use a radar level meter.

• 1. Core principles

  High-frequency microwave pulse emission → reflection on liquid/solid surface→ The meter calculates the emission and echo time and converts the liquid level height. Advantages: not affected by temperature, pressure, steam, dust, non-contact, maintenance-free.
• 2. Check and check before installation

  (1) Confirm: range, antenna type (speaker/parabola/stick), explosion-proof, anti-corrosion, process temperature and pressure, power supply (24VDC), output 4–20mA/HART
  (2) Appearance: The antenna is bump-free, the thread/flange is intact, and the sealing gasket is complete
  (3) Contraindications: It is forbidden for hard objects to touch the antenna, it is forbidden to exceed the pressure and temperature under working conditions, and dust crystallization conditions are not equipped with dust-proof models that are easy to distort
• 3. Key installation positioning

  (1) General principle of tank top installation It must be vertically downwards facing the material surface, and it is strictly forbidden to skew Distance from tank wall: 1/6 of the ≥ tank diameter Avoid: feed and discharge area, agitator, baffle, column, ladder, weld (to prevent false echo interference)
  (2) Key points of installation of different media Water, oil, low dielectric liquid Choose a horn antenna, install it open and unobstructed, and ensure that the microwave directly hits the liquid surface steam, high-temperature tank, volatile medium Enlarge the speaker Install a waveguide / bypass tube to prevent steam from dispersing and attenuating the signal Powder, particle, dust bin 80GHz high-frequency radar, narrow beam; Try to install it in the center, away from the stacking slope Corrosive media Optional PTFE anti-corrosion stick antenna, full anti-corrosion flange
  (3) Pipe/short pipe installation specifications The inner diameter of the short tube ≥ the diameter of the antenna, and the inner wall is smooth and burr-free The height of the short tube should not be too high to avoid clutter in the tube Flange installation: Diagonally evenly pressed, the gasket is centered, and the antenna is not squeezed
  (4) Waveguide (riser) installation scenario foam, steam, and disturbance liquid level must use a waveguide The inner wall of the tube is smooth, and the opening hole balances the air pressure The bottom of the pipe is opened to prevent siltation, and it is installed coaxively and concentricly
• 4. Wiring and electrical wiring

  (1) Power supply: standard DC24V, two-wire 4–20mA HART
  (2) Shielded cable: the shielded control room is grounded at one end, floating on site, and prevents frequency conversion and motor interference
  (3) Junction box: cable granular lock, outlet facing down, waterproof and dustproof
  (4) Explosion-proof model: it is strictly forbidden to open the lid with electricity, protect the explosion-proof surface, and compact the sealing packing
• 5. Steps for submission and debugging

  (1) Set the tank parameters The tank height, empty tank height, full tank height, and range correspond to 4–20mA
  (2) False echo suppression / interference suppression Store fixed obstacle echoes and filter clutter (the most critical step of radar)
  (3) Damping time setting large fluctuations in liquid level: increase damping by 2–5s; Stable water: 0.5–1s
  (4) Zero point calibration of liquid level When the can is empty, the check shows zero point, and the trace offset is cleared with one click
  (5) Simulated inspection Observe the echo curve: the main peak is clear and there is no miscellaneous peak = the installation is qualified
• 6. Daily use and maintenance

  (1) Maintenance is almost free under normal working conditions
  (2) Dust, condensation, hanging material: Regularly stop the machine to purge the antenna (compressed air is lightly blown)
  (3) Insulation and anti-condensation in winter, and outdoor sunshade and rain cover
  (4) It is strictly forbidden to disassemble with pressure, and the pressure is relieved and the power is cut off before maintenance

How to install and use a float switch.

• I. Working Principle

  It uses liquid buoyancy to drive the float ball to flip / magnetic attraction action, with internal contacts opening and closing to control pump start/stop and high/low level alarm.
• II. Applications and Prohibitions

  Suitable for: tap water, sewage, water tanks, pools, general acid and alkali corrosion-resistant conditions Prohibited for: high-temperature oils, strongly corrosive solvents, large particles that easily clog, directly powering high-power motors
• III. Cable Float Switch (Plastic Spherical Type) Installation and Use

  (1) Installation and Fixation Fix the upper end of the cable at the top edge of the water tank/pool, do not pull or let it hang under stress Adjust the hanging cable length to control: Deeper submersion = larger start-stop level difference Short cable = small high-low level range, prone to frequent start/stop Ensure the float can swing freely: do not get stuck on walls, pipes, or entangled
  (2) Installation Prohibitions Do not tie too tightly to clamp the float body Do not submerge the cable entry port (easily leads to water ingress and damage) Keep away from water inlet impact areas and vortex disturbance areas
  (3) Wiring Core (Most Important) Internal OPEN NO / CLOSED NC For water replenishment and automatic water supply: use normally open NO For water shortage protection or high overflow alarm: use normally closed NC Do not directly connect to high-power pumps; an AC contactor / intermediate relay must be installed for capacity expansion
• IV. Rod Stainless Steel Float Switch Installation and Use

  (1) Vertical upright installation, rod must not tilt
  (2) Avoid installation at: material inlet wash, debris accumulation, stirring areas
  (3) Ensure the internal magnet moves smoothly up and down with the float, not jamming the rod and not rusting or deforming
  (4) Metal tank must be reliably grounded to prevent interference
• V. Commissioning and Testing Steps

  (1) Turn on water and check whether the float can rise and sink freely
  (2) Manually flip / lift the float and use a multimeter to measure normal open/closed switching
  (3) Verify control logic: stop at full water, start when water is lacking
  (4) Adjust the cable length to increase the water level difference to prevent frequent pump start/stop
• VI. Common Fault Quick Handling

  (1) Level reached but no action Float jammed, internal contact burned, NO/NC wired wrong → clear debris, rewire, replace float
  (2) No water but always alarming or always on Float filled with water and sank, cable insulation damaged → replace with new
  (3) Frequent start/stop or oscillation Level difference too small, water surface wave disturbance → lengthen stroke, add stabilizing cylinder
  (4) Easily burns the switch Direct load connection, no relay → install contactor for isolation protection

How to select a PT100 temperature transmitter

• Step 1: Match the PT100 sensor with wiring

  Confirm the sensor parameters and grade: Must choose PT100 (IEC60751), 0℃ resistance 100Ω, conventional temperature measurement -200℃~550℃; for temperatures above 550℃, thermocouples are preferred. Accuracy grade: Class A (±0.15℃@0℃), Class B (±0.3℃@0℃); Class B is commonly used in industry, Class A is chosen for precise scenarios (pharmaceutical/semiconductor).
• Step 2: Select installation type

  Integrated (head-type): PT100 wiring box converts locally to 4-20mA, strong anti-interference, cable-saving (2-wire), long distance >50m, strong electromagnetic interference (next to inverters/motors), no RTD module required. Din rail (panel-mounted): Inside control cabinet, easy to calibrate/replace, no contact with the field, multiple channels for centralized control, frequent maintenance needed, multiple measuring points. Field wall-mounted: Mounted on site wall/stand, waterproof and dustproof, local display, outdoor/harsh environment, local reading required.
• Step 3: Core electrical parameter selection

  1. Range (narrow rather than wide, improves accuracy) - Set according to actual working conditions: e.g., water temperature 0~100℃, steam 0~200℃; 4mA = lower limit, 20mA = upper limit, the narrower the range, the higher the accuracy. - Common ranges: -50~50℃, 0~100℃, 0~200℃, 0~400℃ 2. Accuracy (select according to process requirements) - Basic: ±0.5% FS (general industry) - Common: ±0.2% FS (most working conditions) - Precision: ±0.1% FS (pharmaceutical/food/metrology) - Key: annual drift ≤0.05% FS/℃, long-term stability. 3. Output signal (for PLC/DCS connection) - Standard: 4-20mA two-wire (most common, anti-interference, long-distance 1km). - Digital: HART (superimposed on 4-20mA, remote range adjustment/diagnosis), RS485-Modbus (multi-node, networking). - Less used: 0-10V (prone to interference, short distance). 4. Isolation (important for anti-interference) - Recommended: input-output-power three-way isolation, prevents ground loop, resists common-mode interference (required near inverters/high-power equipment). 5. Load capacity - 4-20mA: load 0~500Ω, meets regular PLC/instrument reception.
• Step 4: Environment and safety (adapt to site conditions)

  1. Protection level - Indoor: IP54; Outdoor/dust/humidity: IP65/IP67 (rainproof/dustproof). 2. Explosion-proof (required for hazardous areas) - Chemical/oil & gas: Ex d IIC T6 (flameproof), Ex ia IIC T6 (intrinsically safe), temperature group adapted to the site. 3. Temperature adaptability - Operating temperature: -40℃~85℃ (general); for high-temperature sites choose high-temperature type, for low-temperature sites choose wide-temperature type.
• Step 5: Power supply and communication (final check)

  - Power: industrial standard DC24V (12~36V wide-voltage more stable); two-wire 4-20mA self-powered, no extra power required. - Communication (smart version): HART (mainstream, handheld device debugging), Modbus RTU (RS485), wireless (LoRa/NB-IoT, no wiring scenario).

How to select an ultrasonic flow meter

• 1. distinguish between two categories

  (1) External clip-on (clamp-type) ultrasonic flowmeter  Features: no pipe break, no production stoppage, no holes, maintenance-free, portable inspection  Applicable: pure water, circulating water, sewage, fire water, oil, clean pipe wall without serious scaling  Not applicable: Pipe lining rubber/anti-corrosion layer is too thick, a large number of bubbles, high turbidity mud  Advantages: The first choice for renovation projects, old pipelines, and temporary metering, and the installation cost is extremely low
  (2) Pipe section type (integral flange / thread) ultrasonic flow meter  Features: higher measurement accuracy, strong stability, anti-bubble better than external clamping type, factory calibration  Applicable: clean water, process cooling water, tap water, precision metering, trade settlement  Disadvantages: It needs to be installed with water and pipe breaks, and the cost is higher
  (3) Plug-in ultrasonic flow meter It is installed with open holes and pressure, and is commonly used in medium and large diameter municipal pipe networks and sewage mains
• 2. Confirm the tested medium

  (1) Clean water / softened water / pure water: universal for the whole series, preferential clamping type or pipe section type
  (2) Industrial circulating water and slight sediment: choose high-precision anti-turbidity models and increase the probe
  (3) Sewage and wastewater: avoid severe working conditions of microscopic bubbles, and give priority to insertion/pipe sections
  (4) Oil, diesel, lubricating oil: special liquid calibration probe, ordinary water probe is prohibited
  (5) Strictly prohibited working conditions: high gas content, large number of solid particles, viscous slurry (ultrasonic attenuation measurement is not accurate)
• 3. Pipeline parameters must be checked

  (1) Pipe diameter DN: DN15~DN6000 full coverage, small diameter priority pipe section type, large diameter preferential clamping/insertion
  (2) Pipes:  Carbon steel, stainless steel, cast iron: universal fit PVC/PPR plastic pipes: special plastic pipe calibration parameters  Lined with FRP, rubber, anti-corrosion thick layer: ordinary clamping type is prohibited, and the signal penetration is poor Pipe wall thickness, new and old degree, scaling situation: Severe scaling must be cleaned or replaced with other principle flow meters
• 4. Flow rate & flow rate range

  (1) Industrial recommended economic flow rate: liquid: 0.5~6m/s The optimal range is less than 0.3m/s: the measurement error becomes larger, and the diameter is reduced as much as possible
  (2) Accounting: The ratio of maximum flow, minimum flow and common flow range is reasonable, and "large meter measurement and small flow" are avoided.
• 5. Accuracy level selection

  (1) Normal working conditions (circulating water, auxiliary metering): ±1.0%~±2.0%
  (2) Process control and energy statistics: ±0.5%
  (3) Trade settlement and water handover: high precision of pipe section type ±0.3%
• 6. Output & power supply signal (docking PLC/DCS)

  (1) Power supply: AC220V/DC24V industrial standard
  (2) Analog output: 4-20mA (general)
  (3) Digital communication: RS485-Modbus, HART
  (4) Pulse output: cumulative flow far transmission
  (5) In-situ LCD display: instantaneous flow, cumulative total, flow rate
• 7. Installation environment & protection level

  (1) Indoor cabinet: IP54
  (2) Outdoor, pump room, humid and rainy: IP65/IP67
  (3) Explosion-proof area (chemical oil and gas): choose explosion-proof / intrinsically safe explosion-proof type Ex d IIB T4
  (4) Temperature: conventional -20°C~+60°C, high-temperature medium selection of high-temperature resistant probes
• 8. Requirements for installing straight pipe sections

  Upstream: 10x DN straight section  Downstream: 5 times DN straight section Elbow, valve, and pump outlet need to be lengthened, otherwise the disturbance will affect the measurement
• 9. Quick selection recommendation template

  (1) Old factory renovation, non-stop water, circulating clean water → External clip-on ultrasonic flow meter
  (2) Integrated ultrasonic of new pipelines, precision metering, water trade settlement → pipe sections
  (3) Municipal large-diameter sewage mains, non-stop production with pressure → Plug-in ultrasound
  (4) Ultrasound of small diameter DN15-DN50 clean water → special tube section with priority small tubules

How to select an ultrasonic level meter.

• 1. Suitable for Measurement

  Clear water, wastewater, acidic and alkaline solutions, particulate dust, silo granules, no strong steam, no large foam solid/liquid. Not suitable (conventional ultrasonic strictly prohibited) Violent boiling, large amounts of water vapor, foggy environments (sound wave absorption, blind spot interference) Strongly corrosive volatile fumes, sealed high-pressure tanks Ultra-high viscosity slurry, thick surface foam, strong wave-absorbing powders (ultrafine talc, carbon powder) Recommended alternatives for the above scenarios: radar level meter, guided wave radar, submersible level meter.
• 2. Core Measuring Distance & Range Selection

  Measuring blind spot Factory default near-field blind spot: small 0.3~0.5m, medium to large 0.8~1.5m Selection must ensure: minimum liquid level > blind spot height Maximum measuring distance selection principle Actual tank height × 1.2~1.5 to leave margin and avoid over-range when full.
• 3. Medium Classification Selection

  Clear water, tap water, circulating water: economic general ultrasonic is sufficient Acidic and alkaline corrosive liquids: choose PVDF corrosion-resistant probe, corrosion-resistant housing.
• 4. Installation Structure

  The smaller the beam angle, the better (narrow beam resists interference, avoids tank wall/pipeline obstruction) Installation methods Threaded installation: DN50, small tanks, sealed basins Flange installation: large storage tanks, corrosion-resistant, explosion-proof scenarios Bracket hanging: sewage tanks, sedimentation tanks, open pools Installation taboos: avoid feed inlets, agitators, tank wall beams, spray splash areas
• 5. Electrical Parameters (for integration with control system)

  Power supply: DC24V (industrial mainstream)/AC220V Signal output Standard: 4-20mA analog Communication: RS485-Modbus (networked remote transmission) Relay switch: high/low level alarm, pump start/stop control Protection level Indoor pump room: IP65 Outdoor exposed, waterproof and dustproof: IP67
• 6. Explosion-proof & Corrosion-resistant Selection

  Ordinary non-hazardous areas: ordinary economical type Chemical oil & gas, flammable and explosive tanks: intrinsically safe Ex ia IIC T4/T6 explosion-proof ultrasonic Strongly corrosive acids and alkalis: PVDF probe, aluminum alloy corrosion-resistant housing, fully sealed with potting
• 7. Environmental Temperature and Pressure

  Conventional working conditions: -20℃~60℃, general open pool at atmospheric pressure High-temperature steam, high-temperature tanks: ultrasonic not recommended, switch to radar Pressure vessels: low pressure and slight pressure can use special pressure-resistant type, high pressure preferably radar
• 8. Quick Selection One-Click Template

  Ordinary municipal sewage tanks/sedimentation tanks (atmospheric, no foam or steam) → general ultrasonic level meter, 4-20mA Chemical acid and alkali storage tanks, corrosive liquids → PVDF corrosion-resistant probe, flange installation, corrosion-resistant housing

How to select a gear flow meter.

• 1. First, distinguish the types

  Elliptical Gear Flow Meter Mainstream, volumetric type, suitable for medium to high viscosity liquids, heavy oil, resin, lubricating oil, heat transfer oil, asphalt, hydraulic oil; high accuracy, dirt-resistant, suitable for trade settlement. Micro Precision Gear Flow Meter Small flow, micro-measurement, glue, ink, additives, pharmaceuticals, low-viscosity precise batching; pulse signal, high precision.
• 2. Viscosity Matching

  Low viscosity 1–5 mPa·s: choose precision small module gears, anti-slip compensation type. Medium viscosity 5–500 mPa·s: standard elliptical gear universal model (best cost-performance). High viscosity 500–10000 mPa·s: increased gap, high-viscosity dedicated reduction structure, insulated jacket type. The higher the viscosity, the more accurate the volumetric gear meter, with greater advantage over turbine/vortex meters.
• 3. Flow Diameter Selection

  Select based on commonly used instantaneous flow, not rigidly based on pipeline diameter. Each model has a minimum-to-maximum flow ratio (range ratio 10:1~50:1). Optimal accuracy when common flow is within 30%–80% of range. Below minimum flow: gears do not rotate, measurement inaccurate. Beyond maximum flow: rapid wear, pressure loss spikes. Example: common engine oil 80L/min → select corresponding model, do not blindly match DN50 pipeline.
• 4. Accuracy Grade Selection

  General industrial oil supply, lubrication: ±0.5% FS Batching, chemical additives, oil statistics: ±0.2~±0.3% Trade settlement, precise filling, metering handover: ±0.1% high-precision volumetric
• 5. Material Selection

  Housing: cast steel, stainless steel 304, 316L Gears/rotors: cast iron, stainless steel, hard alloy, wear-resistant PEEK (for very small flow/ corrosive media) Seals: Ordinary oil: NBR nitrile rubber Solvent, aromatic, chemical oil: FKM fluorine rubber High-temperature operation: high-temperature resistant special seals
• 6. Temperature & Pressure

  Normal temperature: -20 to 80℃ standard version High-temperature heat transfer oil, asphalt: 200–300℃ high-temperature insulated jacket type Pressure rating: PN16, PN25, PN40; select high-pressure custom type for high-pressure hydraulic systems
• 7. Signal Output and Power Supply

  Basic: pulse/square wave output Remote: 4-20mA analog Communication: RS485-Modbus, HART On-site: LCD local display of instantaneous and cumulative total
• 8. Installation Requirements

  No need for straight pipe sections before or after (advantage of volumetric, easier than turbine) Must install: inlet filter (prevent impurities from jamming gears) For high-viscosity media: recommended bypass, insulation, heating Avoid negative pressure suction and air bubbles at inlet and outlet
• 9. Quick Selection Template for Scenarios

  Engine oil, hydraulic oil, lubricating oil supply statistics → Cast iron elliptical gear, 0.5 class, pulse output Resin, glue, syrup, high-viscosity additives → Stainless steel high-viscosity dedicated, wear-resistant gear Micro-dosing, ink, flavor, pharmaceutical ratio → Micro precision gear flow meter Heat transfer oil, high-temperature asphalt → Insulated jacket, high-temperature seal, high-temperature type Chemical corrosive media → 316L housing, PEEK gear, fluorine rubber seal

How to select an electromagnetic flow meter.

• 1. Electromagnetic Flowmeters Only Measure Conductive Liquids

  Applicable: Tap water, sewage, acidic/alkaline/saline solutions, ores, slurry, chemical conductive wastewater, emulsions Conductivity threshold: Generally ≥ 5 μS/cm; strictly prohibited for ultrapure water < 5 μS/cm
• 2. Matching Pipe Diameter & Flow Rate

  Economically optimal flow rate: 1.0–3.0 m/s Low-flow media prone to sedimentation (sewage, ore slurry): choose 1.5–3 m/s to prevent sediment blocking Clean conductive liquids: 0.8–2.5 m/s is sufficient Selection mnemonic: Do not determine diameter based on the pipe; calculate diameter based on actual flow Flow rate < 0.5 m/s: accuracy drops significantly; recommend reducing diameter Flow rate > 4 m/s: lining and electrodes wear quickly, high pressure loss, high noise Example: DN50 pipe, economic flow range approximately 7.07–21.20 m³/h
• 3. Liner Material Selection

  Liner material suitable operating conditions: Rubber (natural / hard rubber): Sewage, tap water, general wastewater, wear-resistant and shock-resistant, high cost performance. PTFE (Polytetrafluoroethylene): Strong acids, strong bases, corrosive chemical media, sanitary grade. PFA: High-purity pharmaceutical liquids, fine chemicals, more corrosion-resistant than PTFE, negative pressure resistant. Polyurethane PU: Mining slurry, sand-containing sewage, extremely wear-resistant.
• 4. Electrode Material Matching

  304/316L: Ordinary water, municipal sewage, neutral liquids (standard universal) Hastelloy C: Highly corrosive chemicals, chloride media Titanium Ti: Seawater, saline solutions, strong alkalis Tantalum Nb: Strong acids (hydrochloric acid, dilute sulfuric acid) Platinum-iridium alloy: Ultra-high corrosion resistance, high-purity fine chemicals, strong oxidizers
• 5. Accuracy and Excitation Mode

  Accuracy level: Ordinary water supply / sewage: ±0.5%, ±1.0% Process control / energy measurement: ±0.3% Trade settlement / water utility handover: ±0.2% Excitation type: Low-frequency square wave excitation: Conventional conditions, stable, anti-interference, mainstream choice High-frequency excitation: Slurry, pulsating fluids, noisy conditions, prevents zero drift
• 6. Structural Type Differentiation

  Integrated type: On-site display, simple installation, preferred for indoor / standard outdoor Remote type: Instrument pits, high-temperature tanks, high humidity, long-distance signal transmission scenarios, display head away from measuring tube
• 7. Pressure, Temperature, and Protection Level

  Nominal pressure: Regular PN10, PN16; high-pressure pipelines choose PN25/PN40 Operating temperature: Rubber liner: ≤ 80℃ PTFE/PFA: ≤120℃–180℃ Protection level: Indoor pump room: IP65 Outdoor submerged, ground pit: IP67/IP68 (submersible type)
• 8. Explosion-proof, Grounding, and Electrical Output

  Explosion-proof: Flammable and explosive chemical areas → flameproof / intrinsic safety Ex d IIC T4 Grounding: Corrosive, metal anti-corrosion pipes, plastic pipelines must be equipped with grounding rings / electrodes to eliminate interference drift Signal compatibility: Power supply: AC220V / DC24V Analog: 4–20 mA standard Communication: RS485-Modbus, HART Pulse: Remote cumulative flow
• 9. Quick Selection Scenario Templates

  1. Municipal domestic sewage / tap water: DN matched flow rate, rubber liner, 316L electrodes, integrated type, IP67, 4–20 mA 2. Acid, alkaline, corrosive chemical liquids: PTFE liner, Hastelloy / tantalum electrodes, corrosion-resistant flange 3. Mining tailings, sand slurry: Polyurethane wear-resistant liner, special wear-resistant electrodes 4. Instrument pit, underground water accumulation environment: Remote type, IP68 submersible protection

How to select a capacitive level meter.

• 1. Core Principle

  Detect liquid level using changes in the dielectric constant of the medium, contact-type capacitive sensing. Suitable for: liquids, viscous slurries, powder particles, sewage, acids and bases, asphalt, glue, oils, high temperature and high pressure, small tanks, stirred tanks.
• 2. Probe Rod Type Selection According to Working Conditions

  (1) Single Rod with Insulation Sleeve (PTFE/PFA) Universal best-seller: acid and alkali corrosion, sewage, chemical solutions, food slurry, slight adhesion Temperature resistance: -40 to 180°C, preferred for corrosion resistance
  (2) Coaxial Tube Type Low dielectric constant, light oils, pure water, organic solvents, high anti-interference, stable measurement
  (3) Cable-Extended Type Large range (3m–20m), silos, deep wells, storage tanks for granular materials
  (4) High Temperature and High Pressure Special Rod Steam pressure tanks, heat transfer oil, reaction vessels; pressure resistance PN16~PN64, temperature resistance 200°C
• 3. Material Matching

  Protective sleeve: 304 / 316L stainless steel Insulation coating: PTFE (Polytetrafluoroethylene): strong acid and alkali, corrosion resistant, mainstream general use PFA: high-purity pharmaceutical, high temperature, vacuum-resistant, better permeation resistance Seals: FKM (fluorine rubber, oil and chemical resistant), silicone (food low temperature)
• 4. Selection by Medium Dielectric Constant

  High dielectric (sewage, acids and bases, aqueous solutions): standard type is sufficient Medium dielectric (oils, organic solvents): special adjustable sensitivity type Low dielectric (dry powder, plastic particles, ultra-pure liquids): high-frequency reinforcement with intelligent compensation calibration
• 5. Special Adaptation for Working Conditions

  High temperature and high pressure, sealed pressure tanks: integrated high-temperature and high-pressure flange, explosion-proof sealing, high-temp dedicated electronic module Explosion-proof areas: Ex ia IIC T6 intrinsic safety / Ex d explosion-proof type, essential for chemical oil and gas
• 6. Electrical Output & Power Interface

  Power supply: DC24V (industrial automation) Continuous measurement: 4-20mA, RS485-Modbus, HART On-site: LED indicator / local LCD display
• 7. Installation Methods

  Threaded installation: small tanks, DN25/DN50, simple at atmospheric pressure Flange installation: high pressure, corrosion resistance, explosion-proof, chemical reaction vessels Top insertion: vertical storage tanks, general-use silos
• 8. Quick Application Selection Template

  Acid and alkali chemical storage tank → PFA fully coated corrosion-resistant rod, flange installation Oil, diesel, lubricant tanks → Coaxial special low dielectric type Powder silos, deep granular raw material tanks → Extended cable-type capacitive probe Stirred reaction vessels, viscous slurry → Anti-adhesion self-calibrating continuous capacitive level meter Chemical explosion-proof areas → Intrinsically safe / explosion-proof type

How to select a float switch.

• 1. First, choose the major category (based on usage scenarios)

  (1) Cable-type float (most commonly used for fully automatic water supply and drainage) Features: low price, simple installation, freely suspended, can automatically start and stop the water pump Applications: sewage tanks, water tanks, basement sumps, residential water supply
  (2) Lever-type float (multi-point control, industrial tanks) Features: fixed-point switch, corrosion-resistant, can be used for multiple high and low liquid level alarms Applications: chemical tanks, wastewater troughs, fire water tanks, situations requiring fixed control points
  (3) Small plastic rod float (micro-equipment) Applications: water purifiers, cooling towers, small cabinets, pure water machines, small containers
• 2. Material selection (determines corrosion resistance, temperature resistance, and lifespan)

  PP Plastic (Polypropylene): conventional clean water, sewage, weak acids and bases. Operating temperature: 0–60℃. Most cost-effective, mainstream on the market PVDF (Polyvinylidene Fluoride): strong acids and bases, chemical corrosive liquids, solvents. Temperature resistant, corrosion-resistant, scale-resistant 304/316 Stainless Steel: drinking water, food, high-temperature oil, sanitary conditions. 316L resistant to chloride ions, seawater Silicone / Foam Sealing: high-temperature resistant, waterproof, airtight, prevents water ingress failure
• 3. Cable selection (key for cable floats)

  Ordinary PVC: normal temperature clean water, indoor use Oil-resistant rubber cable: oily environments, pump rooms, wear-resistant and tensile PUR Polyurethane: corrosion-resistant, hydrolysis-resistant, sewage/chemical, long-term outdoor submersion For long-term underwater use, PUR cable is preferred
• 4. Control point length and installation

  Cable float: spacing between two floats determines the high and low liquid levels Lever float: customize reed switch points as needed (1 point / 2 points / 3 points alarm) Installation methods: side-mounted, top-mounted, suspended, threaded
• 5. Electrical parameter matching

  Contact capacity: Low voltage: 10W High voltage: 50W Output: normally open NO / normally closed NC, choose based on water supply/drainage Voltage: AC220V, DC24V universal
• 6. Temperature condition matching

  Normal temperature: ≤60℃ PP universal Medium temperature: 80–100℃ stainless steel / high-temperature plastic High temperature >100℃: ordinary floats prohibited, switch to electrode / temperature-specific lever float
• 7. Special condition selection

  Chemical strong acids and bases: PVDF corrosion-resistant float, corrosion-resistant cable Food and pharmaceutical pure water: 316 stainless steel sanitary grade, seamless polished High-pressure, pressurized tanks: high-pressure sealed lever float, pressure-resistant structure Explosion-proof workshops: explosion-proof float switch (Ex d IIB T4)
• 8. Quick selection one-sentence template

  Ordinary water tank / water supply and drainage → PP cable float, ordinary cable Sewage tank / basement sump → PP thickened, PUR corrosion-resistant cable Chemical acid and alkali tanks → PVDF corrosion-resistant float Drinking water / food equipment → 316 stainless steel float Requires high and low dual control points → lever multi-point float

How to select a radar level meter.

• 1. Understand the core advantages (why choose 80G)

  80GHz belongs to FM continuous wave FMCW and millimeter-wave radar Extremely small blind spot, ultra-narrow beam angle, anti-foam/steam/slight dust, suitable for small tanks/reactors/narrow vessels, viscous and easy to hang, high precision
• 2. Key 1: Determination of dielectric constant ε (the bottom line of whether it can be measured or not)

  ε ≥4 (water, acid and alkali, sewage, salt water): The general standard model can be chosen ε=2~4 (diesel, engine oil, organic solvents): increase the gain, increase the horn ε < 2 (light hydrocarbons, liquefied gases, very low dioxide oil): 80G is not recommended, and guided wave radar is used instead
• 3. Key 2: Range & Blind Spot Reservation (Easiest to Choose Wrong)

  Blind zone: 80G blind zone is extremely small, conventional 0.08~0.15m, low measurement is worry-free Selection range: The actual tank height × 1.2 times the safety margin For example, if the tank is 6m high→ choose 0~8m specification Not allowed: Full tank approaches the gauge and liquid level enters the blind zone
• 4. Key 3: Antenna structure matching working conditions (anti-hanging, anti-condensation)

  Mini Lens Antenna (Explosive) Applicable: small tanks, reactors, pharmaceutical fine chemicals, narrow pipe mouths, sanitary grade, and slight hanging Features: small size, no dust accumulation, and minimal blind spot Extended speaker dust-proof and anti-condensation type Suitable for: steam, volatile mist, condensation, easily adhering liquids With purge interface, anti-condensation, self-cleaning Corrosion resistant full PTFE antenna Applicable: strong acids and alkalis, corrosive chemical liquids, chemical storage tanks Sanitary clamp food grade Applicable: beverage, pharmaceutical, aseptic working conditions, 3A certification, polishing without dead ends
• 5. Key 4: temperature and pressure matching

  Normal temperature and pressure: -40~80°C standard universal High temperature working conditions: 120°C / 200°C high temperature heat dissipation isolation model Pressure Tank: PN16, PN25, PN40 High Pressure Sealing Flange Negative pressure / vacuum tank: special vacuum sealing structure
• 6. Key 5: Install the interface form

  Small threads: G11/2, M24×1.5, DN50 (small cans, narrow pipe openings) Flange Installation: DN80/DN100 (Anti-corrosion, high-pressure, explosion-proof, standard for large storage tanks) Hygienic Quick Load: 50.5 Chuck (Food & Medicine) Installation is a hard taboo Avoid feed sprinklers, mixing paddles, and tank wall reinforcements ≥ 200mm from the tank wall, tilt 10~15° to prevent false echo Do not face the vortex or liquid level disturbance center
• 7. Key 6: Precision, output, and power supply

  Accuracy: ±1mm~±2mm (high-precision process / trade settlement) Power supply: DC24V two-wire system Signal: 4-20mA, HART, RS485-Modbus In-situ: LCD display, lid-free configuration
• 8. Explosion-proof & protection

  Normal indoor: IP67 Outdoor rain and dust: IP68 Chemical flammable and explosive: Ex d IIC T6 flameproof / Ex ia intrinsically safe
• 9. One-click selection template for working conditions

  Small stirring reactor with foam / water vapor: 80G lens mini radar anti-condensation flange mounted Acid-alkali corrosion chemical storage tank: full PTFE anti-corrosion antenna 316L shell anti-corrosion flange Pharmaceutical and food sterility working conditions: hygienic clamp polished mirror 3A certification Tank with severe vapor volatilization and condensation: extended dust-proof horn, purge port, high temperature isolation Narrow pipe mouth, low level measurement: small blind area lens model small thread interface

What factors need to be considered when selecting a thermocouple?

• 1. Thermocouple Type Selection (Step One, Determine Maximum Measurement Temperature)

  K Type (Nickel-Chromium / Nickel-Silicon): -40 to 1200℃, general purpose, cheapest, preferred for boilers, hot air, flue gas J Type: -40 to 750℃, for oily environments, internal combustion engines, low-temperature flue gases, magnetic and prone to oxidation E Type: -40 to 900℃, highly sensitive at low temperatures, good stability S/R/B Type Platinum-Rhodium: 1300 to 1600℃ high temperatures, kilns, sintering, precision temperature measurement, expensive Mnemonic: Choose K type for under 1200℃; for higher temperatures, platinum-rhodium is a must
• 2. Measurement Temperature and Margin

  Reserve 20% extra capacity based on long-term working temperature Avoid operating near the upper limit for extended periods: oxidation, drift, wire breakage, scrap
• 3. Protective Tube Material (Core for Corrosion Resistance, Wear Resistance, and Lifespan)

  304 Stainless Steel: air, ambient flue gas, neutral media 310S/2520 High-Temperature Stainless Steel: 1000-1200℃ high-temperature furnaces, annealing furnaces 316L: weak acids and bases, chloride ions, chemical corrosion Corundum Ceramics: over 1300℃, oxidizing atmosphere, high-temperature kilns Silicon Carbide, Alloy Wear-Resistant Tips: dust, particle erosion, fluidized beds, clinker conditions
• 4. Structural Form

  Armored Thermocouple: flexible, shock-resistant, fast response, can be bent, general-purpose choice Assembled Type: bulky and durable, high-temperature resistant, strong protection, slow response Wear-Resistant Coating / Hard Alloy: fly ash, ores, particle erosion applications
• 5. Installation and Fixing Method

  Threaded Fixing: M27×2, G1/2, commonly used in pipelines and equipment Flange Fixing: high pressure, high temperature, tank, high sealing requirement Adjustable Ferrule: adjustable insertion depth, easy maintenance Hygienic Clamp: food and pharmaceutical sterile conditions
• 6. Insertion Depth

  Pipeline Temperature Measurement: insert probe to 1/3–1/2 of the pipe diameter Too shallow: measures pipe wall temperature, inaccurate; too deep: high resistance, easy breakage from vibration
• 7. Matching with Environmental Atmosphere (often overlooked, prone to aging)

  Oxidizing/Air Atmosphere: K type or platinum-rhodium suitable Reducing, gas, hydrocarbon atmosphere: use special anti-corrosion alloy or external protective tube, avoid standard K type Sulfur, chlorine corrosion: standard stainless steel prohibited, choose corrosion-resistant material
• 8. Compensation Wire Matching (preventing cold junction error)

  Strictly use dedicated compensation wires corresponding to type: K with KX, S with SX, not interchangeable, otherwise temperature difference error is significant
• 9. Response Speed, Vibration Resistance, Protection

  Thin wall / thin insulation layer: fast response High vibration equipment: choose armored shockproof with reinforced base Protection level: IP54 standard, IP65/IP67 for outdoor humid or dusty environments
• 10. Explosion Proof, Transmitter Output

  Chemical flammable and explosive areas: explosion-proof / intrinsically safe thermocouples Need remote 4-20mA signal: integrated temperature transmitter thermocouple

What factors need to be considered when selecting a thermal resistance?

• 1. Graduation Number and Accuracy Class (Basic Key)

  Standard: Pt100 (IEC60751), resistance 100Ω at 0℃ Accuracy: Class A: ±0.15℃@0℃ (precision, pharmaceutical, instrument calibration) Class B: ±0.30℃@0℃ (general industrial, cost-effective) Do not mix Cu50 and Pt1000, match with secondary instruments/ transmitters
• 2. Temperature Measurement Range

  Conventional Pt100: -200 to 550℃ For temperatures above 550℃, use thermocouples Leave a 15% margin based on the actual medium temperature to avoid long-term overheating aging
• 3. Lead Wire Configuration (Determines Measurement Error)

  Three-wire: Industrial mainstream, compensates for lead wire resistance error, preferred on-site Four-wire: Laboratory/high-precision measurement, completely eliminates lead wire error Two-wire: Only for short distance and low cost, high error, not recommended for process use
• 4. Protective Tube Material (Core for Corrosion Resistance, Wear Resistance, and Lifespan)

  201/304 stainless steel: clean water, air, neutral medium 316L: sewage, weak acid/alkali, chloride ions, general chemical Hastelloy/Titanium: strong corrosion, seawater, saline solution Corundum ceramic: high temperature, wear-resistant, oxidative furnace
• 5. Probe Structure and Installation Fixation

  Fixing methods: thread (M27×2, G1/2), flange, clamp (hygienic grade), removable thread Temperature sensing type: assembled, armored (flexible, shock-resistant, fast response) Insertion depth: generally insert 1/3 to 1/2 of pipe diameter into the center of the pipeline to avoid inaccurate shallow measurement
• 6. Response Time and Insulation Sealing

  Bare element/thin-walled tube: fast response Thickened protective tube: wear-resistant but slow response Sealing: high-temperature filler, moisture-resistant potting, prevents condensation and water-induced drift
• 7. Environmental Condition Protection

  Protection level: IP54 standard, choose IP65/IP67 for outdoor humid and dusty conditions Shock resistance: for high equipment vibration, choose armored shockproof type Explosion-proof: for flammable and explosive chemical areas, choose flameproof/intrinsically safe explosion-proof RTD
• 8. Whether to Match with Temperature Transmitter

  If local remote transmission 4-20mA is needed: select an integrated temperature transmitter module If the control cabinet already has RTD input: a three-wire platinum RTD can be used directly

How to select a thermal gas mass flow meter

• 1: Clarify the characteristics of the gas medium

  This is the primary step in the selection process, which directly determines whether the flowmeter can be accurately measured.
  (1) Gas composition Single gas: such as compressed air, nitrogen, oxygen, natural gas, etc., can be calibrated directly according to the type of gas. Gas mixture: Manufacturers must be provided with detailed components and volume percentages of each component (e.g., O₂, CO₂, N₂ content in flue gas). Because the thermal conductivity and specific heat capacity of different gases are different, the changes in composition will directly affect the measurement accuracy. If the components are unstable, the measurement error will increase. Special Note: acetylene gas is generally not suitable for use with thermal flow meters.
  (2) Gas cleanliness and humidity Thermal flow meters are best for measuring clean, dry gases. Dust/Oil: If the gas contains dust, oil mist, or water vapor, they can attach to the sensor, causing measurement drift or even failure. For slightly soiled applications, you can choose between plug-in or models with special protection designs. For heavily polluted media, other types of flow meters should be considered. Condensation: It is necessary to ensure that the gas does not produce condensation at operating temperature, otherwise it will affect the measurement.
• 2: Determine the working condition parameters

  This step ensures that the flow meter can work safely and stably in your field environment.
  (1) Flow range Determine the minimum, common, and maximum flow in real-world applications. Key Principle: Although thermal flow meters have a wide range ratio (up to 100:1), it is recommended that common flow points be between 20% and 80% of their range to ensure optimal accuracy. When selecting the upper range, it is recommended to leave a margin of more than 20%.
  (2) Working temperature and pressure Temperature: Confirm the maximum and minimum operating temperatures of the gas. Conventional models are typically suitable for -40°C to 200°C, while high-temperature models (with cooling unit) can withstand media such as flue gases up to 400°C. Pressure: Confirm the working pressure of the pipe. The withstand pressure of conventional models is generally 1.6MPa to 2.5MPa, and high-pressure models (such as for natural gas pipelines) can withstand pressures of 4.0MPa or even more than 10MPa. When selecting a model, it is necessary to ensure that its withstand pressure level meets the requirements. Pipe size
  (3) Confirm the nominal diameter (DN) of the on-site pipeline. This is the main basis for choosing the structure type of the flow meter.
• 3: Select the structure type and installation

  Based on your pipe size and site conditions, determine the most suitable physical structure and installation method. Structural type
  (1) Pipe section type (pipe type) Applicable: Usually used for small and medium-diameter pipes below DN100. Advantages: Factory overall calibration, high precision, easy installation (flanged or threaded connection). Disadvantages: high cost for large diameters, installation needs to cut off pipes.
  (2) Insertion Application: Generally used above DN65, especially for large diameter pipes (such as above DN200). Advantages: Cost-effective, pressurized installation and maintenance, minimal pressure loss. Disadvantages: There are requirements for the flow field of the installation point, and the accuracy is slightly lower than that of the pipe section type. Installation requirements: Straight pipe section: In order to ensure the stability of the flow field, it is usually required to have a straight pipe section with a pipe diameter of ≥ 10 times (10D) upstream and a pipe diameter of ≥ 5 times (5D) downstream. Vibration: The probe of a plug-in flow meter must be securely fastened and avoid pipe segments with strong vibrations that can damage the sensor or cause measurement interference. The pipe section type is not sensitive to general vibration. Flow direction: Pay attention to the flow direction arrow on the flow meter housing during installation to ensure that the installation direction is correct.
• 4: Determine the electrical parameters and functions

  Determine the electrical configuration of the switch based on your control purpose and system integration needs.
  (1) Output signal According to the needs of the back-end control system (such as PLC, DCS), select the appropriate output signal: Analog Signal (4-20mA): The most commonly used standard signal in industrial automation. Pulse/frequency signal: Used for total metering. Digital communication (RS485, Modbus, HART): for advanced applications that require remote parameter setting and reading of multiple data.
  (2) Power supply Confirm whether the field power supply is DC 24V or AC 220V.
  (3) Explosion-proof and protection level Explosion-proof certification: In petroleum, chemical, natural gas and other environments where flammable and explosive gases exist, models with corresponding explosion-proof certifications (such as Ex d, Ex ia) must be selected. Protection level: For outdoor or dusty and humid environments, choose products with higher protection levels (such as IP65 and above).
  (4) Other functions Display head: You can choose between one-piece (the meter head and sensor are integrated) or split (the meter head is connected by a cable to facilitate reading at high altitudes or in situations where it is difficult to observe).
  (5) Response time: The dynamic response of thermal flow meters is relatively slow (time constant is about 1-5 seconds), which is not suitable for the measurement of pulsating flow.

How to select a RF admittance level switch

• Step 1: Measure the characteristics of the medium clearly

  This is the primary step in selection, which directly determines whether the switch can work effectively. Dielectric Constant (ε) This is the core parameter of RF admittance technology. The dielectric constant of the material to be tested must be ≥ 1.6. If the dielectric constant is below 1.6 (such as some dry polyethylene particles), the signal will be too weak to be detected, and options such as tuning forks or guided wave radar should be considered. Material type and physical properties Type: Specify whether it is powder (e.g. fly ash, cement), granules (e.g. plastic particles, grain) or liquid/slurry. Adhesion: For materials that are easy to stick, easy to clump or wet (such as mud and gypsum), products with anti-hanging (anti-adhesion) technology must be selected. This technology eliminates the influence of adhesions on measurement through the protection electrode circuit, which is the core advantage of RF admittance technology. Density and impact: For materials with high density or falling from a height, the impact force can damage the probe, so choose a model with protective measures.
• Step 2: Analyze working conditions and environmental conditions

  The physical conditions of the installation environment determine the structural strength, material, and safety of the switch. Process temperature and pressure Temperature: Confirm the maximum operating temperature of the material. Standard models are typically suitable for -40°C to 180°C, while high-temperature models (probes made of special materials such as ceramic) can withstand extreme environments up to 250°C to 450°C. Pressure: Confirm the operating pressure of the container. RF admittance switches are typically used in atmospheric or microvoltage environments, with a withstand voltage of generally within 2MPa, and special high-voltage models up to 10MPa. When selecting a model, it is necessary to ensure that its withstand pressure level meets the requirements. Explosion-proof and protection requirements Explosion-proof certification: In chemical, pulverized coal silos and other environments where flammable and explosive gases or dust exist, models with corresponding explosion-proof certifications (such as Ex d IIC T6, ATEX, IECEx) must be selected. Protection Level: For dusty, wet, or outdoor environments, choose products with higher protection ratings, such as IP65, IP66, or IP68, to ensure the safety of the electronic unit.
• Step 3: Determine the installation method and probe structure

  This step ensures that the switch can be properly installed and adapted to the physical constraints of the site. The installation method is connected to the process Mounting Position: Determine whether it is top-mounted or side-mounted. The installation position should avoid the feeding port to prevent the material from directly impacting the probe. Process connection: According to the tank or pipeline interface, choose the appropriate connection method, the common ones are threaded connection, flange connection and clamp connection. Probe type and size Insertion depth: The length of the probe (insertion depth) must ensure full access to the material at the alarm point. At the same time, the length of the protective pole must be at least 50mm deep into the silo to ensure that the anti-hanging function functions effectively. Probe Structure: Standard type: suitable for general dust and particles. Protective type: Stainless steel protective sleeve is added to the standard probe, which can effectively resist the impact of heavy materials, and is suitable for harsh working conditions such as ash hoppers and ore silos. Cable type: suitable for large silos or containers with large depths, which can avoid the lateral force bending of the long rod probe. Ultra-high temperature type: using ceramic and other special material probes, specially used in metallurgy, chemical and other ultra-high temperature environments.
• Step 4: Determine the electrical parameters and functions

  Determine the electrical configuration of the switch based on your control purpose and system integration needs. Output signal The most common is a relay output (such as the DPDT double pole, double throw), which is used to directly control a pump, valve, or alarm. Some models also offer 4-20mA analog or digital communication signals such as HART and Modbus for integration into more complex control systems. Supply voltage Confirm whether the field power supply is AC 220V or DC 24V. Smart features Many modern RF admittance switches have functions such as one-click automatic calibration, fault self-diagnosis, and delayed alarm (to avoid false alarms caused by material fluctuations), which can greatly simplify commissioning and maintenance.

How to select a submersible liquid level sensor

• 1. Applicable

  It is suitable for the measurement of static pressure in open atmospheric pressure pools, sewage, circulating water, weak acids and alkalis, oils, underground deep wells, and water tanks. Simple installation, cost-effective, and no straight pipe section.
• 2. Range selection

  Principle: Liquid level height = hydrostatic pressure column pressure Conversion: 1 meter of water ≈ 9.8kPa ≈ 1000mmH₂O Selection principles: Actual maximum liquid level × 1.25 times the safety margin Example: Pool depth 4m → Selection range 5m (49kPa) It is forbidden to use low-level hard-top high voltage and low-level range measurement (plummeting accuracy)
• 3. Probe core material & anti-clogging

  Diaphragm/body 304 Stainless Steel: Clean Water, Ordinary Sewage, Neutral Media (Standard) 316L stainless steel: chemical weak acid and alkali, seawater, chloride ion working conditions Hastelloy / Titanium: Strong corrosion salt, strong alkali (strong corrosion required) Anti-blocking structure Plain flat film: clean water Isolation anti-siltation damping cap: sewage, sediment-containing sediment, sedimentation tank (preferred, anti-silt plugging) Large particle media: with stainless steel filter anti-plug model
• 4. Cable and ventilation structure

  Special breathable cable for air conduction: the internal capillary is connected to the atmosphere to offset the atmospheric pressure error Waterproof tensile PE/PUR sheath General environment: PE Oil, pull resistant, chemical: PUR polyurethane
• 5. Temperature and accuracy level

  Temperature range Regular: -20°C~ 60°C High temperature medium: up to ≤ 80°C, and the over-temperature is changed to radar/immersive high-temperature special model Precision Civil water tank, water replenishment control: ±0.5% FS Industrial sewage and water statistics: ±0.25% FS Precision Process: ±0.1% FS
• 6. Electrical output and power supply

  Power supply: standard DC24V Analog Output: 4-20mA (two-wire, industrial anti-interference) Digital communication: RS485-Modbus (network remote transmission, multi-point monitoring) Optional: Display the meter head in situ
• 7. Protection, explosion-proof, and installation

  Protection: IP68 diving grade (no problem with long-term immersion underwater) Explosion-proof: Chemical oil and gas flammable zone → intrinsically safe Ex ia IIC T6 Installation method: Jump straight to the bottom of the pool (easiest) Wellhead fixed hook, tie rod protection, casing anti-shaking
• 8. Quickly select the scene template

  Waterworks, clean water tanks: 304 probe anti-siltation cap range 1.25 times 4-20mA IP68 Municipal sewage, sedimentation tank, sediment included: 316L weighted anti-blocking damping structure PUR tensile cable Seawater, salt, weak corrosion chemicals: 316L / titanium alloy diaphragm anti-corrosion breathable cable Underground deep wells and pumping room sumps: Extended gas conduction cables and heavy hammers to prevent floating Chemical explosion-proof area: intrinsically safe explosion-proof isolation and anti-corrosion probe

How to select a vortex flowmeter.

• 1. Confirm the applicable medium first

  Suitable for: gas, steam, clean liquid Compressed air, nitrogen, oxygen, saturated/superheated steam, cooling water, oil, pure water
• 2. Brief description of measurement principles

  The fluid flows through the triangular column to form a Carmen vortex, and the vortex frequency is proportional to the flow velocity. Advantages: no moving parts, durable, temperature and pressure compensation, high cost performance of steam metering
• 3. Precise selection of pipe diameter & flow rate (the most important thing, don't be rigid according to the pipe)

  (1) Recommend economic flow rate Liquid: 0.6~2.5 m/s Gas: 6~25 m/s Saturated steam: 8~30 m/s
  (2) Selection principle The caliber is calculated according to the actual common flow, not according to the on-site pipeline Flow rate is too low: no vortex, no measurement, poor accuracy → need to reduce the diameter Excessive flow rate: loud noise, high pressure loss, and instrument impact damage Simple caliber logic Small caliber DN15–DN50: liquid, small gas volume Medium diameter DN65–DN200: Circulating water, compressed air, steam main specifications Large diameter DN250 and above: gas main, municipal steam supervisor
• 4. Selection of body material

  304 Stainless Steel: Water, Air, Normal Steam (Standard) 316L stainless steel: corrosive water vapor, trace chloride ions, chemical media Special: Anti-corrosion lining, Hastel alloy (very rarely used for strong corrosion)
• 5. Temperature and pressure & compensation method (steam must see)

  Normal liquid/gas: 4-20mA is sufficient to display on the spot Saturated steam: must be temperature compensated, automatic density conversion mass flow rate Superheated steam: must be double compensated with temperature and pressure Withstand voltage: PN16 / PN25 / PN40 (steam priority PN25 and above) Temperature resistance: conventional ≤ 250°C; High temperature steam 350°C, 450°C customized version
• 6. Accuracy level

  Liquid: ±1.0%~±1.5% Gas / Steam: ±1.5%~±2.0% High Precision Intelligent Type: ±0.75%
• 7. Classification of installation structure

  Integrated display type: direct reading on site, commonly used for pipeline ground installation Split remote transmission type: high-temperature steam, high-altitude pipelines, instrument wells, and meter heads are far away from high-temperature areas Flange Clamping / Flange Connection: Clamping type: cheap, normal pressure and normal temperature Flange type: high pressure, high temperature, steam, industrial mainstay
• 8. Rigid requirements for the front and rear straight pipe sections (the error of 90% is from here)

  Upstream: Front 30~40DN straight pipe Downstream: Rear 5~10DN straight pipe Elbows, valves, pumps, and expansion joints must be lengthened in the straight pipe section, otherwise the vortex disorder will be measured and floated
• 9. Electrical signal output

  Power supply: DC24V/AC220V Analog: 4-20mA Pulse: Frequency output (cumulative metering) Communication: RS485-Modbus, HART In-situ LCD: instantaneous/cumulative, temperature and pressure compensation values
• 10. Explosion-proof and protection

  Normal working conditions: IP65 Outdoor rain: IP67 Flammable and explosive gases / Chemical area: Ex d explosion-proof / Ex ia intrinsically safe
• 11. Scene quick selection template

  Circulating cooling water, pure water: 304 clamping vortex street integrated display 4-20mA Compressed air and nitrogen metering: special range for gas, increased vortex street probe, temperature and pressure compensation optional Saturated steam boiler room: flange high temperature type automatic temperature compensation PN25 split optional Superheated steam main: Temperature and pressure double compensation high pressure flange stainless steel 316L Chemical explosion-proof gas: explosion-proof vortex street anti-corrosion body

How to select a turbine flow meter.

• Step 1: Define fluid properties

  This is the basis for selection, which directly determines the material, structure and applicability of the flowmeter. Fluid type First, it is clear whether it is measuring liquids (such as water, oil, chemicals), gases (such as natural gas, air) or steam. Different types of fluids have very different design requirements for flow meters, such as gas turbine flow meters often have a smaller impeller inertia than liquid ones to accommodate low-density media. Fluid physical properties Viscosity: Turbine flow meters are especially suitable for clean, low-viscosity fluids (generally below 30 cP is recommended). High viscosity fluids can significantly increase bearing friction, affect measurement accuracy, and even cause impeller jamming. Corrosiveness: Choose compatible materials based on the chemical properties of the fluid. Common options include 304/316 stainless steel, which may require Hastelloy, titanium, or PTFE (polytetrafluoroethylene) linings for highly corrosive media. Cleanliness: Turbine flow meters are very sensitive to impurities. If the fluid contains impurities such as solid particles, fibers, etc., a filter must be installed at the front end to prevent impurities from wearing out the bearings or jamming the impeller.
• Step 2: Determine the working condition parameters

  This step ensures that the flow meter can work safely and stably in your field environment. Flow range Determine the minimum and maximum flow in the actual application. The range of the selected flow meter should fully cover this range with some margin. Key Principle: To guarantee optimal accuracy and longevity, it is recommended that the flow meter's common flow points be between 20% and 80% of its range. Avoid long-term operation at the lower limit of flow (large error) or upper limit (fast wear). Working pressure and temperature Pressure: The rated working pressure of the flow meter must be higher than the maximum operating pressure of the piping system to ensure safety. Temperature: The operating temperature of the fluid must be within the range allowed by the flow meter. High temperatures can affect seal life and electronic component performance, while low temperatures can affect material strength. Pipe size Confirm the nominal diameter (DN) and connection method (e.g., flange, thread) of the pipe in the field. A flow meter consistent with the pipe diameter is often chosen to avoid unnecessary pressure loss and installation complexity.
• Step 3: Choose Functions and Structures

  Determine the functional configuration and physical structure of the flow meter based on your specific application purpose and site conditions. Accuracy level Turbine flow meters typically have an accuracy of between ±0.5% and ±1.0%. For cases that require extremely high accuracy, such as trade settlement, high-precision (such as ± 0.2% or ±0.5%) models should be chosen. For general process monitoring, medium accuracy (e.g., ±1.0%) is usually enough and more cost-effective. Output signal According to the needs of the back-end control system (such as PLC, DCS, display instrument), select the appropriate output signal: Pulse/frequency signals: for total metering and integration with computer systems. Analog Signal (4-20mA): The standard signal used in industrial automation for teletransmission and process control. Digital communication (RS485, Modbus, HART): for advanced applications that require remote parameter setting and reading of multiple data. Structure type and installation Internal structure: Prefer a turbine flow meter with thrust reversing structure. This design keeps the impeller in "suspension" over a certain flow range, reducing axial friction and wear on the bearing and significantly extending its service life. Bearing material: Bearings are wearing parts. For clean fluids, wear-resistant materials such as tungsten carbide and ceramics can be selected; For gas metering like natural gas, tungsten carbide bearings are a common choice. Connection methods: Common ones are flange connection (suitable for medium and high pressure, medium and large diameter), threaded connection (suitable for small diameter and high pressure pipes) and sanitary clamp connection (used in the food and pharmaceutical industries). Installation requirements: In order to ensure the smooth flow of fluid through the impeller, sufficient straight pipe sections need to be reserved before and after the flow meter, which is generally required to be 10 times the pipe diameter in the front and 5 times the pipe diameter in the back. Special requirements Explosion-proof certification: In environments with flammable and explosive gases such as petroleum, chemical, and natural gas, flowmeters with corresponding explosion-proof levels (such as Ex d, Ex ia) must be selected. Temperature and pressure compensation: For gas measurement, because the gas volume is greatly affected by temperature and pressure, if you need to measure the volume or mass flow in the standard state, you should choose an integrated or split flow meter with temperature and pressure compensation function.

How to select a pressure transmitter

• 1. First distinguish the type of measurement

  Gauge Pressure G: Measure relative atmospheric pressure, conventional pipeline and tank pressure (90% industrial general) Absolute pressure A: Vacuum, closed negative pressure, altitude working conditions, always based on absolute zero point Differential pressure DP: liquid level, throttle flow, pressure difference at both ends, closed tank level measurement Negative pressure/vacuum: special for vacuum pumps, suction air, and negative pressure pipe networks
• 2. Range selection

  1MPa ≈ 1000kPa ≈ 102 meters of water column Normal Static / Steady Pressure: Actual maximum pressure × 1.25 times margin Pulse, water hammer, pump outlet impact conditions: magnified to 1.5~2 times Optimal use range: 30%~80% of the full scale, the most stable accuracy
• 3. Accuracy and stability grading

  Economical general: ±0.5% FS (water supply, HVAC, general auxiliary control) Industry Standard: ±0.25% FS (Chemical, Water Treatment, Automation Control) High Precision Intelligence: ±0.075%~±0.1% FS (Trade Settlement, Precision Craft, Laboratory) Long-term stability: Preferably drift ≤ 0.1% FS per year
• 4. Diaphragm/wetted material

  316L stainless steel: clean water, circulating water, compressed air, neutral oil (standard for universal) Hastelloy C: chloride ions, salt solution, strong corrosive chemical media Tantalum Ta / Titanium Ti: strong acids, strong alkalis, seawater, halides Monel: Working conditions of lye and hydrogen Sealing fluorine materials: NBR ordinary oil and sewage, FKM fluoroelastomer chemical resistance, EPDM acid and alkali resistance
• 5. Structural form distinction

  Ordinary compact: pipe wall mounting, low cost, conventional room temperature Intelligent digital display: see the pressure value on the spot, and press the button to clear the configuration Heat dissipation high-temperature type: steam, high-temperature heat conductive oil (media> heat dissipation pipe must be selected at 80°C) Flat diaphragm / hygienic type: viscous slurry, food and medicine, easy to crystallize and prevent blockage Diaphragm flange remote transmission type: high viscosity, crystallization, strong corrosion, negative pressure closed tank
• 6. Pressure interface installation specifications

  Regular threads: M20×1.5, G1/4, G1/2 High Pressure / Chemical: Flange DN15/DN25 Hygienic food: Clamp Quick Release 50.5
• 7. Electrical output & power supply (docking PLC/DCS)

  Universal standard: DC24V, 2-wire 4-20mA Smart configuration: HART protocol (remote modulation, zero point, diagnostics) Digital communication: RS485-Modbus (multi-site networking) Local: LCD display, key migration and clearing
• 8. Environmental protection & explosion-proof

  Degree of protection: conventional IP65; Outdoor rain and dust IP67 Temperature: Standard -20°C~ 70°C; High temperature medium with radiator Explosion-proof areas (chemical, oil and gas, dust) Original safety: Ex ia IIC T6 Flameproof: Ex d IIC T4/T6
• 9. Quick scene selection template

  Tap water, pumping room pipes, air compressors: 316L diaphragm gauge pressure 1.25 times the range 4-20mA IP65 Steam and high-temperature thermal pipe network: high-temperature type with heat sink pipe, voltage upgrade, intelligent digital display Chemical acid and alkali, salt water corrosion medium: Hastelloy / tantalum diaphragm anti-corrosion seal intelligent HART Viscous mud, easy to crystallize materials: flush diaphragm / flange diaphragm remote pressure transmitter Chemical plant explosion-proof workshop: intrinsically safe / flameproof type anti-corrosion wetted HART

How to select a tuning fork level switch.

• Step 1: Measure the characteristics of the medium clearly

  Media type Liquids: water, oil, acid and alkali, mud, beverages, etc. Solids: powders (such as flour, cement), granules (such as plastic particles, grains), lumpy materials, etc. Difference: While some tuning fork switches can be tested with both liquid and solid, specialized models designed for specific media, especially low-density solids, offer higher sensitivity and reliability. Media density This is one of the most critical physical parameters. The tuning fork switch works by detecting changes in the vibration frequency of the fork, and the medium density must be higher than the minimum detection density of the switch, otherwise it cannot effectively dampen the fork vibration, resulting in the inability to trigger the signal. Liquids: Standard types typically measure liquids with densities as low as 0.5 g/cm³ and compact versions around 0.7 g/cm³. Solids: Dedicated solid tuning fork switches measure materials with densities as low as 0.008 g/cm³. When selecting, it is necessary to confirm that the medium density is within the detection range of the switch. Corrosiveness and viscosity Corrosiveness: For corrosive media such as acids and alkalis, the material of the fork body and process connectors should be 316L stainless steel or anti-corrosion designs such as PTFE coating. Viscosity/Hanging: For high-viscosity liquids or solids that are easy to stick to and agglomegate, choose a compact tuning fork or a fork with a polished surface to reduce the impact of material hanging on the measurement.
• Step 2: Analyze working conditions and environmental conditions

  The physical conditions of the installation environment determine the structural strength and safety of the switch. Process temperature and pressure Temperature: Confirm the maximum and minimum operating temperatures of the media inside the container. Standard types are typically suitable for -50°C to 150°C, while high-temperature types can withstand media up to 250°C. Pressure: Confirm the working pressure of the container to ensure that the pressure resistance level of the tuning fork switch meets the requirements to ensure tightness and structural strength. Explosion-proof requirements If it is used in chemical, dust workshops, and other environments where flammable and explosive gases or dust are present, it is necessary to choose a model with corresponding explosion-proof certification (such as Ex d IIC T6 Gb flameproof type or Ex ia IIC T6 Ga intrinsically safe type). Vibration and interference If there is mechanical vibration or material shock in the silo (such as near the feeding port), choose a model with good seismic performance and ensure that the installation position can avoid direct material impact.
• Step 3: Determine the installation method and electrical parameters

  This step ensures that the switch is properly installed and interfaces seamlessly with your control system. Installation method and size Mounting Position: Determine whether it is top-mounted or side-mounted. The installation position should avoid the feeding port to prevent the material from directly impacting the fork body. Process connection: According to the tank or pipeline interface, choose the appropriate connection method, the common ones are threaded connection, flange connection and sanitary clamp connection. Insertion Depth: Determine the appropriate probe length (insertion depth) based on the thickness of the tank wall or the desired probing position to ensure that the fork body can fully contact the material. Electrical parameters Output signal: The most common is the relay output (normally open/normally closed), which is used to directly control the pump or alarm. Depending on the control system requirements, a two-wire, PNP/NPN, or NAMUR signal may also be required. Supply voltage: Confirm whether the on-site power supply is AC 220V or DC 24V. Protection level: For dusty or humid outdoor environments, choose products with higher protection levels (such as IP65 and above) to ensure the safety of internal circuits.

How to select an oil float switch.

• Step 1: Clarify the characteristics of the measurement medium

  The physical and chemical properties of the oil are the primary factors in selecting the sensor, as they directly determine the material and structural compatibility of the sensor. Oil type: Determine whether it is gasoline, diesel, lubricating oil, hydraulic oil, or other specialty oils. Different oils have varying levels of corrosiveness, dielectric constants, and viscosity. Corrosiveness: For corrosive oils or environments that may come into contact with water, acids, or alkalis, the sensor material must be corrosion-resistant. Recommendation: Prefer float balls made of corrosion-resistant materials such as 316L stainless steel or plastics like polypropylene (PP) and PTFE (polytetrafluoroethylene). Viscosity: For relatively viscous media such as engine oil or heavy oil, avoid choosing complex float structures to prevent the float from sticking or jamming. Recommendation: Choose float designs with smooth surfaces and simple structures.
• Step 2: Analyze operating conditions and environmental factors

  The installation environment has a decisive impact on the stability and lifespan of the sensor. Temperature and pressure: Confirm the maximum operating temperature of the oil and the system pressure of the tank. High temperature: Choose a high-temperature-resistant model to ensure that seals and internal electronic components (such as reed switches) can operate stably at high temperatures; ordinary plastic floats may not be suitable for high-temperature environments. High pressure: The sensor must withstand the operating pressure of the tank to prevent deformation or leakage. Vibration and impact: In highly vibrating environments such as construction machinery, ships, or generators, the sensor structure must be robust. Recommendation: Choose models with no moving parts or those with vibration-reducing designs, such as certain vertical rod float switches. Safety requirements: If used in flammable environments such as gasoline, the sensor must have appropriate explosion-proof certification (e.g., Ex d IIB T4 Ga) to prevent electrical sparks from causing hazards.
• Step 3: Determine installation method and functional requirements

  Based on the tank structure and control objectives, choose the appropriate installation type and function. Installation method: Top installation: The float switch is inserted vertically from the top of the tank, suitable for most scenarios. Side installation: Installed horizontally from the sidewall of the tank, suitable for spaces with limited room or where top installation is not possible. Cable-suspended: The float is suspended in the tank using a cable, suitable for deep tanks or irregularly shaped containers and is less prone to blockage. Functional requirements: Point control: Only need to detect high-level (overflow prevention) or low-level (dry-run prevention) alarms. This is the most common application of float switches. Continuous measurement: If real-time, continuous monitoring of oil percentage is required, choose magnetostrictive or Hall effect level sensors with analog output (e.g., 4-20mA), rather than simple switches. Electrical parameters: Confirm the rated voltage and current of the switch to ensure it can directly drive pumps, relays, or alarm lights.

How to select a rotary paddle level switch.

• 1. Applicable

  Suitable for: particles, powder, plastic particles, grain, feed, fly ash, wood chips, cement silo level alarm
• 2. Shell protection and installation form

  Shaft length classification Standard short shaft: 300mm, 400mm (small silo, side mounting) Extended shaft: 500–2000mm (top-mounted, deep silo) Casing extension type: ultra-high material level, anti-material impact and swing Installation method: Side mounting thread: G1 inch, diagonally mounted 15°–20° anti-jamming material Flange top mounting: DN65, large material tank, load-bearing and impact-proof Protection level Regular IP54; Dust silo / outdoor must be IP65
• 3. Blade selection

  (1) Straight blades Characteristics: Simple structure, long strip shape. The blade area is large, the damping force is strong, and the shaft has a good protective effect. Applicable materials: mainly suitable for materials with small specific gravity and good fluidity. Typical applications: lightweight powders, plastic granules, grains, feed, etc.
  (2) Blade blade Features: The blade area is large, shovel-shaped, which can provide greater damping torque and high detection sensitivity. Applicable materials: suitable for materials with small specific gravity. Typical applications: flour, starch, fly ash, lime powder, etc.
  (3) Flag-shaped blades Features: The blade size is small, which can effectively reduce the impact of the material on the blade. Applicable materials: suitable for materials with large specific gravity. Typical applications: ores, metal particles, sand and gravel, etc.
  (4) Sickle-type blades Features: Curved sickle-shaped, compact structure, can withstand large impact loads. Applicable materials: suitable for materials with high density, poor fluidity or easy agglomeration. Typical applications: cement, coal, clay, limestone, etc.
  (5) Folded plate-shaped blades Features: Folded shape, large surface area, help remove debris and scale, reduce material adhesion. Applicable materials: suitable for viscous materials or working conditions that are prone to fouling. Typical applications: Viscous powders or granules in food processing, chemical industry.
• 4. Torque sensitivity adjustment

  Heavy materials (stones, slag, granules): increase torque Light powder (gray powder, wood powder): reduce the torque With adjustable damping torque structure, it eliminates misoperation
• 5. Temperature level selection

  Normal Temperature Type: -20~+80°C (General Powder, Grain) Medium temperature and high temperature resistant type: +120°C, +200°C (drying material, hot air silo) Rotation resistance is not recommended at more than 200°C, and RF admittance is used instead
• 6. Voltage & contact output

  Power supply: AC220V (industrial mainstream), DC24V optional Switching signal: SPDT passive relay (normally open/normally closed), directly connected to PLC, alarm, discharge valve, interlock
• 7. Explosion-proof & anti-corrosion

  Ordinary dust workshop: standard dust-proof type Flammable and explosive dust (plastic powder, flour, aluminum powder): dust explosion-proof Ex tD Slightly corroded water vapor: stainless steel shaft, anti-corrosion shell
• 8. Strengthen the configuration under special working conditions

  Blanking direct flushing, large ore → plus anti-collision guard, weighted base, and reinforced spindle Light and fine powder, easy to idle and slip → Enlarge blades + micro torque adjustment The silo vibration is large→ anti-vibration damping, anti-false alarm structure Easy bridge mounting → Extension shaft + eccentric mounting
• 9. One-click quick selection template

  Cement silos, fly ash, light powders: extended shaft + sickle shape + micro torque + IP65 Grain, plastic particles, pellets: standard stub shaft + straight blade + conventional torque Drying high-temperature materials, hot air hoppers: high-temperature resistant + stainless steel spindle Flour, plastic dust explosion-proof workshop: dust explosion-proof type + sealed dustproof structure Large slag and blanking material impact strong: anti-collision protection pipe + reinforced flange installation