● Interference problem: Ask the instrument if there is an external power supply, if there is, remove both the external power supply and the signal line, and observe if it is zeroed with battery power only, if it is zeroed, there is interference and the interference measure that GND is connected to the case ground.
● Whether the valve can guarantee no air leakage after closing.
● The upstream valve is not closed before there is a branch upstream, and when the downstream valve is closed, the fluid in the pipe pulsates when the other branch is running, causing the impeller to rotate.
Solutions：
● The small flow rate does not affect the normal flow rate and can be removed by modifying the parameters.
If the pulsation is caused by the fluid in the pipeline, close the upstream valve.
If the instrument is only battery-powered and is removed from the pipeline, but still goes away, the instrument is a problem and should be returned to the factory for repair.