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Support Center: Guides & FAQs

Find guidance on installation, product selection, technical concepts, and troubleshooting.

This Knowledge Base provides clear answers about compressed air monitoring and SUTO iTEC products. Topics include installation, choosing the right instruments, and solving common issues. We update this section regularly with new content. If you cannot find the information you need, please contact us.

Customer Support

Troubleshooting & Maintenance (8)

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Why does my flow meter always show maximum flow?

Incorrect flow readings can be caused by wrong software settings, sensor contamination or moisture in the system. Regular checks help restore measurement accuracy.

Possible causes:
  • The pipe diameter or measuring range may be incorrectly set in the software.
  • Moisture or liquid water may be entering the sensor, especially in thermal mass models.
  • The sensor could be heavily contaminated with oil or particles.
Solutions:
  • Review the sensor settings in S4C-FS and correct any errors in diameter or flow range.
  • Check the compressed air system’s dew point to ensure no water condensation is reaching the sensor.
  • Inspect and clean the sensor, and make sure filters and dryers are functioning properly upstream.
Tags: contamination, dew point issue, full scale error, max flow reading, overrange, S401, S415, S418, S421, S430, S451, S453, saturated sensor, wet sensor
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Why does my flow meter have power but no output?

No output signal from a flow meter can be caused by incorrect wiring, wrong output scaling, a faulty component or mismatched signal configuration.

Possible causes:
  • The output signal wiring might be connected incorrectly.
  • A fuse or component in the measurement system may be blown.
  • The analog output scaling (e.g., 4–20 mA) might not be correctly configured.
  • The installed output board might not match your system’s signal requirements.
Solutions:
  • Double-check the output wiring using the instructions in the user manual.
  • Use a multimeter to check whether any signal is present on the output lines.
  • Open the S4C-FS software and ensure the correct signal scaling is selected.
  • Confirm that the sensor’s output (e.g., 4–20 mA, Modbus) matches the input expectations of your data logger or PLC.
Tags: 4–20 mA error, analog signal, Modbus signal missing, no output, powered but no reading, S401, S415, S418, S421, S430, S451, S453, scaling, wiring
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Why does my flow meter not match the reading of another flow meter in the same line?

Mismatched flow readings are often caused by leaks, incorrect sensor settings or unsuitable installation points that prevent full flow measurement.

Possible causes:
  • There might be leaks or bypasses between the sensors.
  • One or more sensors might have incorrect scaling or pipe diameter settings.
  • Some sensors might not be measuring the full flow path due to poor installation locations.
Solutions:
  • Check the system for any leakage or open bypass valves.
  • Make sure every flow meter has the correct settings for pipe diameter, gas type, and measurement range.
  • Verify that the sensors are installed in locations where they can measure the complete flow in the pipeline.
Tags: different flow meter type, different installation, inconsistent readings, reference condition error, S401, S415, S418, S421, S430, S451, S453, sensor mismatch, thermal vs pitot
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Why does my flow meter not read accurately or show incorrect values?

Inaccurate flow readings can result from wrong installation, incorrect settings, unsuitable sensor technology or unstable flow conditions in the pipe.

Keyword:

Possible causes:
  • The sensor may be incorrectly installed — for example, not centered or installed at the wrong depth.
  • The wrong gas type, flow units, or reference conditions may be selected in the settings.
  • The inner pipe diameter might be entered incorrectly in the software.
  • The sensor technology may not be suitable for the current application (e.g., thermal mass sensors in very humid environments).
  • There may not be enough straight pipe before or after the sensor, causing turbulent flow.
Solutions:
  • Verify the sensor is properly centered in the pipe and installed at the recommended depth and orientation.
  • Check the gas type, measurement units, and reference pressure/temperature conditions in the S4C-FS software.
  • Enter the correct inner pipe diameter to ensure proper flow calculation.
  • Make sure the sensor technology is appropriate for the gas conditions (e.g., avoid thermal mass sensors where liquid water may be present).
  • Install the sensor with adequate straight pipe lengths before and after, as specified in the manual.
Tags: calibration, inaccurate reading, misconfigured settings, pipe diameter error, S401, S415, S418, S421, S430, S451, S453, wrong gas type, wrong value
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Why does my flow meter read very erratically or show flow spikes?

Fluctuating flow readings are often caused by contaminated gas, turbulent flow or incorrect sensor installation. Stable conditions improve measurement reliability.

Possible causes:
  • The air or gas might be contaminated with moisture, oil, or particles.
  • Turbulent flow caused by nearby elbows, valves, or other obstructions may be affecting readings.
  • The sensor could be loose or not inserted to the correct depth.
Solutions:
  • Inspect filters and dryers upstream of the sensor to ensure clean, dry air.
  • Check for rust, oil, or debris that could be interfering with the sensor element.
  • If possible, move the sensor to a more stable section of the pipe, away from bends or valves.
  • Make sure the sensor is firmly secured at the correct insertion depth and orientation.
Tags: contamination, dirty air, flow spikes, noisy signal, S401, S415, S418, S421, S430, S451, S453, turbulence, unstable flow, unstable readings, vibration
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Why does my flow meter show flow in both directions?

Negative flow readings are usually caused by reversed sensor installation or incorrect flow direction settings in the software.

Possible causes:
  • The sensor may be physically installed in the wrong direction.
  • The flow direction configuration in the software may be reversed.
Solutions:
  • Look for directional arrows on the sensor housing and confirm that they match the actual flow direction.
  • If necessary, update the flow direction settings in the S4C-FS software to correct the reading.
Tags: bidirectional flow, flow arrow wrong, flow back, reverse installation, S401, S415, S418, S421, S430, S451, S453, S4C-FS direction setting
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Why does my flow sensor show flow even when there is no flow in the pipe?

Flow readings at zero demand can result from incorrect zero calibration, moisture or oil contamination, or vibration near the sensor.

Possible causes:
  • A zero-flow calibration has not been performed or was done incorrectly.
  • High humidity or oil residue may cause thermal sensors to register false readings.
  • Nearby machinery or vibrations might create noise signals that are interpreted as flow.
Solutions:
  • Use the S4C-FS software to perform a proper zero-flow calibration with the pipe completely depressurized.
  • Check for moisture or oil using a dew point sensor or monitor.
  • Avoid installing the sensor near sources of vibration, such as compressors or motors, which could affect accuracy.
Tags: false flow, ghost signal, idle flow, moisture, oil in air, S401, S415, S418, S421, S430, S451, S453, sensor drift, zero calibration error
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Why is my flow meter not detected?

Modbus communication problems are often caused by wiring errors, wrong address settings, reversed lines or unstable power supply.

Possible causes:
  • The wiring might be incorrect or the cable could be damaged.
  • The Modbus communication lines (D+ and D−) may be reversed.
  • If you’re using Modbus TCP, the sensor might be connected directly to a PC instead of through a network switch or hub.
  • The configured Modbus address might not match the sensor’s actual address.
  • The sensor may not be powered or the supply voltage could be too low.
Solutions:
  • Compare the wiring with the sensor’s user manual to ensure all connections are correct.
  • Use a multimeter to check for a stable 24 VDC power supply.
  • Test the cable for continuity or try a known working replacement cable.
  • Verify the Modbus address and communication settings using the S4C-FS configuration software.
  • Ensure the cable from the splitter to the sensor is shorter than 30 cm for proper detection.
  • Use the S4C-FS software’s address scan function to detect the sensor on the network.
Tags: detection error, device not detected, flow meter not found, no Modbus connection, no signal, S401, S415, S418, S421, S430, S451, S453, sensor startup, wiring issue
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