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Here’s what happened: The high-level tank is equipped with two level gauges – one is a flap level gauge and the other is a differential pressure transmitter. The level shown on the control panel fluctuated greatly, ranging from 3.78 to 4.08 meters; an alarm was triggered once the level dropped below 4 meters. The instruments on site indicated that the plant should be shut down, as the ball valve could not be closed properly. And what worries me the most isn’t this; it’s the actual level of the liquid. Everyone knows the function of a surge tank – it’s used for pressurization. The liquid level relative to the other high-level tank is 5.12 m. I can’t stay calm at all; I’ve done some analysis on it. I hope fellow users can help with the analysis: 1. Is the differential pressure transmitter damaged? Are there any signs of that? Is the liquid level fluctuating greatly? Is the pressure at the positive pressure port or the negative pressure port unstable? I’m not sure about this 2. Regarding pump issues, if the impeller is malfunctioning, it can be detected by listening to the sound, but there are no abnormal sounds! 3. Motor problems: How can we determine if there are motor issues? Is there significant current fluctuation? (Perhaps it’s possible to tell by reversing the pump, but please provide more detailed explanations. Thank you.)
What is the actual liquid level indicated by the magnetic flap? Comparison of the two level gauges. If they are all the same, the possibility of an instrument failure is very low.
In this situation, it is usually due to an improper U-shaped bend in the pressure tapping tube on the liquid side during installation; vaporization of the liquid occurs inside the pressure tapping tube. The liquid discharged from the tube can remain stable for a short time, but not for long. Replacing the transmitter is ineffective, and considering the regular changes in ambient temperature, it is also necessary to check the insulation of the pressure tapping tube