Cause Analysis:

1.The measured medium has changed.

Solution: Modify the parameters of the measuring medium in the ultrasonic flowmeter.

2.The measured medium vaporizes due to excessive temperature.

Solution: Cool down the medium.

3.The temperature of the measured medium exceeds the limit temperature of the standard sensors.

Solution: Cool down the medium or use the high temperature sensors.

4.The coupling agent under the sensor is over oxidized.

Solution: reapply coupling agent.

5.Due to high frequency interference, the ultrasonic flowmeter exceeds its filter value.

Solution: adjust the position of the ultrasonic flowmeter and stay away from the source of interference.

Cause Analysis:

The sensors are installed too close to the control valve. When the valve is partially closed, the flow meter actually measures the instant increased flow rate by the reduction of the caliber. Solution: Refer to the installation guide and re-install the sensors moderately away from the control valve.

Cause Analysis:

1. The paint or rust on the surface of the pipeline have not been cleaned.

Solution: Re-clean the surface of the pipe then install the sensors.

2.The surface of the pipeline is uneven or the sensors are installed on the welding seam.

Solution: grind well on the pipeline section surface or select another away from the weld pipeline section to install the sensors.

3.The roundness of the pipe is not enough, the inner surface is not smooth, and there is fouling. This may happen for cast iron pipe.

Solution: Polish or choose a smooth surface section.

4.The measured medium is impure liquid or there are solid suspensions.

Solution: Use other types of suitable flowmeters.

5.The sensors are installed on the fiberglass pipe.

Solution: Remove the glass fiber.

6.The sensors are installed on the casing, it will weaken the ultrasonic signal.

Solution: Move the sensor to the pipe section without casing.

7.The sensors are not well coupled with the pipeline, and there are gaps or bubbles on the coupling surface.

Solution: re-install the coupling agent.

Cause Analysis:

The sensors are installed on the top and bottom of the horizontal pipeline. The sediment interferes with the ultrasonic signal. Solution: Avoid installing sensors on the top and bottom sides of the pipe.

The sensors are installed on the pipe where the liquid flows downward, and not filled with fluid. Solution: Install the sensors on the pipe section filled with fluid.

There are devices such as venturi, orifice plates, vortex flowmeters, turbine flowmeters, or partially closed valves that make the flow state violently fluctuate, which are just in the range of the sensor's emission and reception, making the readings inaccurate. Solution: Install the sensor away from the above-mentioned device, the upstream of the sensor is 30D from the above-mentioned device, and the downstream of the sensor is 10D or upstream of the above-mentioned device.

The input pipe diameters do not match the inner diameter of the pipe. Solution: Modify the pipe diameter to match it.

Cause Analysis: 

The pipeline where the ultrasonic flow sensor is installed vibrates greatly or there is a device that changes the flow state (such as the flowmeter installed in the downstream of and close to the regulating valve, pump, and shrinking orifice).

        Solution: Refit the flow sensors in a place far away from the vibration source or move it to the upstream of the devices which changes the flow state.