Problems and Solutions for Ultrasonic Flow Meter
There will be some failures in the use of ultrasonic flowmeter. When there are problems, how should we deal with them? Some common troubleshooting methods are sorted out for your reference:
I Hardware Problem
1. Wrong date and time
2. System data memory error
3. Hardware error of measuring circuit
4. No response of ultrasonic flowmeter button
5. Program ROM check and error
6. Main frequency error of ultrasonic flowmeter, crystal vibration detection
7. The display does not display, or the display is disordered, abnormal operation and other strange phenomena
8. Data memory reading and writing error
EU-108 Ultrasonic Flowmeter
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II Installation Problem
1. No signal output from flow sensor after power on
Possible failure causes and treatment methods:
1) the process medium in the pipeline does not flow. Inform the process operator to open the valve.
2) the process medium in the pipeline flows but the flow rate is low. The wrong selection of the instrument results in too large caliber, so the meter can only be replaced.
3) if the process status is normal, the instrument may have faults, which can be checked and maintained step by step. At present, the eddy frequency detection element, i.e. the probe, is mainly piezoelectric type. The insulation resistance of the probe is measured with a multimeter of 200mf ~ gear, which should be 10 ~ ioom ~ at room temperature. Measure the capacitance of the probe with a multimeter of 2n gear. The capacitance shall be constant between 0.15 and 0.35nf at no load. The amplifying board circuit is provided with the signal check point 0, and the oscillograph is used to check the waveforms of each point one by one. Generally, the signal waveforms at the detection point in front of the Schmitt trigger are sine waves with different amplitude, and the signal waveforms after the Schmitt trigger are square waves.
4) the power supply of the sensor is incorrect. Check whether the + 12VDC or + 24VDC sent by the flow totalizer to the sensor is normal.
5) if the primary instrument is normal after inspection, it indicates that the fault is in the secondary instrument, and the secondary instrument can be inspected.
2. Possible failure causes and treatment methods of sensor signal output when there is no flow in the pipeline:
1) the pipeline vibration makes the sensor output false signal. Find out the vibration source, eliminate the pipeline vibration or reduce the vibration of the process pipeline.
2) poor grounding, interference and false signal. Check the grounding resistance, which should not be greater than 10q, otherwise handle the grounding.
3) the sensor gain is too large. Adjust the gain potentiometer to the appropriate value.
4) there is power frequency interference. Check the output signal frequency of the sensor. If it is 50Hz, it means that there is a high-power motor or a relatively strong electric field near the flowmeter and some measures should be taken to reduce the interference or strengthen the shielding of the signal wire.
3. The output signal of the sensor is unstable under normal flow
1) there is irregular vibration in the pipeline. Find out the vibration source, eliminate the pipeline vibration or reduce the vibration of the process pipeline.
2) the gain of amplifier board is not correct. Use an oscilloscope to check the waveform of the output signal. In case of multiple waveforms and loss of waveforms, it indicates that the amplifier board is not working normally. Multiple waveforms indicate that the gain is too large. Loss of waveforms indicates that the gain is too small. The gain of the amplifier board can be adjusted properly.
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