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Common fault check and treatment method of steam flowmeter

Jul 20, 2017

1, after the power flow sensor no signal output

Possible causes and remedies:

1) The process medium does not flow. Inform the process operator to open the valve.

2) The process medium is flowing but the flow rate is low. Instrument selection errors caused by the diameter is too large, only for the table.

3) If the process status is normal, the instrument may be faulty, you can check the maintenance level. Swirl  frequency detection components that probe is currently the main  piezoelectric, with a multimeter 200Mf ~ file measurement of the  insulation resistance of the probe, at room temperature should be 10 ~  IOOM ~. With  the multimeter 2n file, measure the capacitance of the probe, no load  capacitance should be 0.15 ~ 0.35nF between the constant. In  the amplifier board circuit is set on the signal detection i 0:00, with  the oscilloscope one by one detection of the waveform, usually in the  Schmitt trigger before the detection point, the signal waveform should  be amplitude ranging from sine wave, in Schmidt After the trigger signal waveform for the square wave.

4) The sensor is not powered correctly. Check whether the + 12VDC or + 24VDC supplied to the sensor by the flow totalizer is normal.

5) Check if the instrument is normal, indicating failure in the  secondary instrument, you can check the secondary instrument failure.

2, no flow in the pipeline when the sensor has a signal output possible causes of failure and treatment methods:

1) The pipe vibrates more so that the sensor outputs a false signal. Find the vibration source, eliminate the vibration of the pipeline or the process pipeline damping.

2) poor grounding, the introduction of interference, the emergence of false signals. Check the grounding resistance, should not be greater than 10Q, otherwise the processing ground.

3) The sensor gain is too large. Adjust the gain potentiometer to the appropriate value.

4) There is power frequency interference. Check the sensor output signal frequency, such as 50Hz, indicating the  flowmeter near the high-power motor or relatively strong electric  field, should take some measures to reduce interference or strengthen  the signal line shielding.

3, the normal flow sensor output signal instability

1) There is irregular vibration in the pipeline. Find the vibration source, eliminate the vibration of the pipeline or the process pipeline damping.

2) Amplifier plate gain is incorrect. Use the oscilloscope to check the output signal waveform, if there are  multi-waveform, loss of waveform, indicating that the amplifier board  is not working properly, multi-waveform shows the gain is too large,  lost waveform shows the gain is too small, you can adjust the gain of  the amplifier board.