Fault diagnosis ideas for liquid level instruments

Differential pressure level meters account for a large proportion of level meters, so we will focus on introducing them. The speed of change of the level parameter is closely related to the volume of the container, and whether its change speed is normal should be judged based on the actual situation. For example, the drum level of a boiler changes very quickly, but the level of a liquid storage tank changes slowly. If the level display suddenly changes and fluctuates greatly, such as when it indicates the maximum or minimum, the instrument is likely to be faulty.

When the liquid level display value reaches the maximum or minimum, the differential pressure transmitter should be checked first. If the transmitter is normal, the display instrument is mostly faulty. If the output of the transmitter is consistent with the display of the display instrument, the liquid level control system can be changed to manual operation, that is, manually change the opening of the regulating valve to observe whether the liquid level changes. If the liquid level changes, it is generally due to process reasons. If there is no change, the instrument is faulty.

When the liquid level record curve fluctuates greatly and quickly, it may be that the PID parameters are improperly set or the parameters have changed. The damping of the transmitter is not adjusted properly, and the pressure pipeline leaks, which may cause the liquid level record curve to fluctuate.

The most feared thing when measuring liquid level is the occurrence of false liquid level. If you suspect a false liquid level phenomenon, you must make a calm judgment. You can switch the control system to manual operation, then check or calibrate the transmitter and system, and check all pressure pipes and valves for problems until the problem is found.