Common Fault Handling Method of Flow Meter 2

5. Electromagnetic Flow meter

Phenomenon	Cause	Measure
No flow signal output	1. Instrument power supply is not normal. 2. The cable is not connected properly. 3. Liquid flow conditions do not meet the requirements. 4. The sensor parts are damaged or the inner wall is attached. 5. The converter components are damaged.	1. Check whether the output of the power circuit board is normal. 2. Connect the cables correctly. 3. Check the flow direction of the liquid and whether the liquid in the tube is filled. 4. Regularly clean the covered liquid scar layer. 5. Replace the damaged components.
Output value  fluctuation	1. Electromagnetic interference generated by external stray current. 2. The pipe is not filled with liquid or contains bubbles in the liquid. 3. The power supply board is loose.	1. Check the instrument operating environment whether there is a large electrical or welding machine at work. 2. Make sure the liquid is full of tubes or bubbles are flattened. 3. Disassemble the flow meter and re-secure the circuit board.
The flow measurement value does not match the actual value	1. Transmitter circuit board is broken down. 2. Liquid flow rate is too low, containing tiny bubbles. 3. The signal cable is not connected properly. 4. The parameter setting of the converter is not accurate.	1. Check whether the transmitter circuit board is in good condition or not. 2. Ensure that the flow rate of the liquid under test is above the minimum flow limitation. 3. Check whether the signal cable connection and cable insulation are in good condition or not. 4. Re-set the converter settings value and verify the zero and full values of the converter.
Output signal over range	1. Signal cable wiring is wrong. 2. The parameters of the converter are set incorrectly. 3. The converter and sensor models are not matched.	1. Check the signal loop connection. 2. Check the parameters of the converter settings and zero, full compliance with the requirements. 3. Replace the converter and sensor models.

6. Vortex flow meter

Phenomenon		Cause	Measure
There is no output of the flow meter in the pipe	No display No output in the flow meter	1. The power supply has failed. 2. The power supply is not connected. 3. The cable is disconnected or the border is faulty.	1. Re-supply or replace the power supply. 2. Turn on the power. 3. Reconnect the cable and check the cable.
	The instrument   Shows no output	1. The flow is too low to enter the measuring range. 2. There is a fault on the board. 3. The probe is damaged. 4. The pipe is blocked or the sensor is stuck.	1. Increase the flow or re-select the flow meter. 2. Replace the electronic board. 3. Replace the probe. 4. Re-install the flow meter.

Phenomenon		Cause	Measure
After power supplying, there is no power flow but output	The output signal is stable	1. The output frequency is 50 Hz frequency interference. 2. The magnifying plate is damaged and self-excited.	1. Use a shielded cable to re-connect  the wiring. 2. Replace the amplifier.
	The output signal has changed	1. There is a strong electrical device or high frequency interference near the flow meter. 2. Pipeline has a strong shock. 3. Amplifier magnification or trigger sensitivity is too high. 4. Pipeline valve is not completely closed, there is leakage.	1. Re-select the installation site. 2. Reinforce the piping of the flow meter mounting section. 3. Decrease the magnification (GB) or sensitivity (SB) counterclockwise. 4. Check the valve.

Phenomenon		Cause	Measure
The flow output is unstable	The reason of choose to install extremely piping	1.There is a strong electrical interference signal, the instrument is not grounded, traffic and interference signal superposition. 2. Straight pipe is not enough or pipe diameter and meter diameter is inconsistent. 3.the impact of pipeline vibration. 4. flow meter installation is different. 5. the fluid is not full tube. 6. the flow below the lower limit or exceed the upper limit. 7. the existence of cavitation in the fluid phenomenon.	1. Re-connect the shield. 2. Replace the installation location again. 3. Reinforce the pipe to reduce vibration. 4. Re-install the meter. 5. Check the fluid flow and its instrument installation location. 6. Increase the flow rate or adjust the amplification plate filter parameters. 7. Install the valve of the instrument downstream, increase the back pressure.
	Instrumentation reasons	1.The instrument menu is set incorrectly. 2.The motherboard is damaged.	1. Set the menu again as required. 2. Replace the motherboard.

7. Coriolis Mass Flowmeter

Phenomenon	Cause	Measure
Instantaneous flow is the maximum value	1. The cable is disconnected or the sensor is damaged. 2. The fuse inside the transmitter burns out. 3. The sensor measuring tube is blocked	1. Replace the cable or replace the sensor. 2. Replace the fuse. 3. After dredging, tap the sensor housing, and then measure the AC and DC voltage, still unsuccessful, that is due to the large installation of stress, then try to re-install.
When the flow rate increases, the Flow meter indicates a negative increase	The direction of the sensor flow is opposite to that of the housing, and the signal line is reversed.	Change the direction ofinstallation, and also change the signal line wiring.
When the fluid flows, the flows hows positive and  negative beating, the range is large and sometimes The negative maximum	1. Power supply AC and DC shielded cable ground is greater than 4Ω. 2. Pipeline vibration. 3. Fluid has two components, that is gas and liquid. 4. There is a strong magnetic field or radio frequency interference around the transmitter.	1. Re-ground. 2.Change the connection pipe with the flow meter to metal hose connection. 3. Punch in the top of the flow meter pipe, and install the valve, used to discharge gas components. 4. Change the surroundings of the transmitter.

8. Ultrasonic flow sensor 

Phenomenon	Cause	Measure
Flow rate shows dramatic changes in data	The sensor is installed in a place where the pipe is vibrating or installed downstream of the control valve, pump, orifice.	Install the sensor in a place away from vibration or move upstream of the changing flow regime.
The sensor is no problem, but the flow rate is low or no flow rate	1. Pipeline paint, rust is not clean. 2. The pipe surface is uneven or installed at the weld seam. 3. The sensor and the pipe coupling is not good, the coupling surface with cracks or bubbles. 4. The sensor is mounted on the casing, which will weaken the ultrasonic signal.	1. Clean the pipe and install the sensor. 2. Install the sensor with the pipe polished or away from the weld. 3. Re-install the coupling agent. 4. Move the sensor to the section with no casing.
The reading value is incorrect	1. The sensor is mounted on the top and bottom of the horizontal pipe, where the sediment interferes with the ultrasonic signal. 2.The sensor is mounted on a pipe with a downward flow of water and pipe is not filled with fluid.	1. Install the sensor on both sides of the pipe. 2. Install the sensor on a fluid-filled pipe section.
The flow meter is working properly and the flow meter is no longer measuring the flow	1. The measured medium changes. 2. The measured medium isgasifieddue to the high temperature. 3. The temperature of the measured medium exceeds the limit temperature of the sensor. 4. The coupling agent below the sensor is aged or consumed.	1. Change the measurement method. 2. cool down. 3. Cooling. 4. Re-coat the coupling agent. 5. Keep away from sources of interference. 6. Reenter the value.