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Typical fault analysis of common flowmeter

Author: Release date: March 29, 2017 09:18:28 Source: Shanghai Cixi View: 103
There are many kinds of flowmeters, and they have their own characteristics in use. However, due to the influence of various factors, the flowmeter will inevitably appear in the use of those problems, so what are the faults of the flowmeter? Today, I will give you an analysis of the typical faults of the common flowmeter.

The first is the turbine flowmeter. Turbine flowmeter is an ideal flowmeter with high measurement accuracy and good repeatability. The typical faults are as follows:

1. The displayed flow rate is inconsistent with the actual flow rate.

Check coil 1 and output resistance.

2. Debris hinders impeller rotation, and remove debris.

3. The impeller is corroded and the blade is deformed. Repair or replace the impeller and calibrate it again.

4. The check valve is not installed and the reverse flow occurs.

5. Insufficient back pressure, resulting in cavitation.

6. Due to the influence of temperature, the fluid viscosity increases.

7. If the fluid temperature is too high or too low, the clearance between the bearing and the shaft changes too much.

2. When the flow is zero, the flow display is not zero and the display value is unstable.

1. Transmission line shielding grounding is poor, interference of external electromagnetic field, check grounding, eliminate interference.

2. If the internal circuit boards or electronic components of the display instrument are deteriorated and damaged, interference will be caused. Take "short circuit method" or check one by one to find out the fault point.

3. If the stop valve leaks, repair or replace the valve.

4. Pipeline vibration causes impeller vibration. Reinforce pipeline or install support before and after flowmeter.

3. The flow shows a gradual decrease.

1. The filter is blocked, and the pressure loss increases gradually, which reduces the flow rate and removes the impurities in the filter.

2. The valve core on the pipeline is loose, and the valve opening is automatically reduced. Repair or replace the valve.

3. If the impeller is obstructed by foreign matters or foreign matters enter into the bearing clearance, the speed will be slowed down due to the increase of resistance. Clean the flowmeter and recalibrate it if necessary.

4. No indication of normal flow of liquid and no increase of accumulated quantity.

1. If the power supply circuit or signal circuit is in open circuit or poor contact, use a multimeter to check and eliminate the fault point.

2. The voltage supplied to the preamplifier is too low, so increase the power supply voltage to the specified requirements.

3. In case of preamplifier fault, if the iron bar moves quickly under the detection head and there is no signal output, check whether the coil is broken and the solder joint is desoldered.

4. If the printed circuit board and connector of the display instrument are in fault or poor contact, replace the printed circuit board.

5. If the impeller is stuck, remove the foreign matters, clean or replace the damaged parts, and recalibrate after replacing the parts.

Secondly, the typical faults of electromagnetic flowmeter are as follows:

1. The instrument has no flow signal output.

1. The instrument power supply is abnormal; confirm that the power supply has been connected, and check whether the output voltage of power circuit board is normal, or try to replace the whole power circuit board to judge whether it is good or bad.

2. The cable connection is not normal; check whether the cable is in good condition and whether the connection is correct.

3. The liquid flow condition does not meet the installation requirements; check the liquid flow direction and whether the liquid in the pipe is full. For the electromagnetic flowmeter which can measure forward and backward direction, if the direction is inconsistent, it can be measured, but the set flow rate does not match the positive and negative directions, which must be corrected. If the workload of removing the sensor is heavy, the arrow direction on the sensor can be changed and the symbol of the display instrument can be reset. The pipeline is not full of liquid, which is mainly caused by the improper installation position of the sensor. Measures should be taken during the installation to avoid the liquid in the pipeline from being filled with the pipe.

4. The sensor parts are damaged or there is an adhesive layer on the inner wall of the sensor; check whether the electrode on the inner wall of the transmitter is covered with liquid scab layer; clean the measuring liquid that is easy to scab regularly.

5. The converter components are damaged; if it is judged that the fault is caused by the damage of converter components, replace the damaged components.

Second, the output value fluctuates.

This kind of fault is mostly caused by the influence of measuring medium or external environment. After the external interference is eliminated, the fault can be eliminated by itself. In order to ensure the accuracy of measurement, such faults can not be ignored. In some production environments, the circuit board of flowmeter will be loose and the output value will fluctuate due to the strong vibration of measuring pipe or liquid.

1. The transmitter circuit board is of plug-in structure. Due to the large vibration of the field measurement pipeline or liquid, the power supply board of the flowmeter is often loose. If it is loose, the circuit board can be re opened.

2. When the pipeline is not filled with liquid or there are bubbles in the liquid, both are caused by the process. At this time, the process personnel can be requested to confirm that the output value can return to normal after the liquid is full or the bubble is recovered.

3. Electromagnetic interference caused by external stray current. Check whether there are large electrical appliances or welding machines in the operation environment of the instrument, and make sure that the instrument grounding and operation environment are good.

At this time, the pulsation can only reflect the flow condition after the flow of the flow meter is eliminated.

The above is the introduction of Shanghai Cixi on the typical fault analysis of common flowmeter, hope to help you, if you still have related product problems, you can call the page for consultation! The company provides 24-hour service!

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