Please help determine the cause of the fault
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The unit under my responsibility contains a horizontal tank, which is a sealed container; the interface level is measured using a double-flange capillary transmitter, with the liquid phase connected to the high-pressure side and the gas phase connected to the low-pressure side. There is an observation hole on the tank; during normal operation, the liquid level is kept at a level where it can be seen through this hole, and at that point the liquid level is roughly around 45. Recently, the inspector found that the liquid level was being controlled at the observation port, but the DCS showed a liquid level of around 75. This indicates that the pressure difference between the positive and negative sides is increasing. Given that the liquid in the tank is relatively clean, I don’t think there’s a high possibility of blockage on the positive pressure side; therefore, I conclude that it is the negative pressure side, That is, the gas phase side, that is blocked. Is there anything wrong with my judgment? It’s not convenient to disassemble and assemble it on the negative pressure side, and I don’t want to waste time due to my own wrong judgment. So please help me make a decision; thank you.
If the gauge is checked and found to be working properly (with a proper zero reading, no blockages or leaks, and no damage to the diaphragm). It is considered to be caused by a change in the density of the process medium. Study the process to see if there have been any changes in operating conditions recently. First, ensure there’s nothing wrong with yourself, and then you can look for issues related to the manufacturing process. This kind of situation occurs quite frequently with differential pressure boundary detection. Just my personal opinion.
The medium being tested doesn’t crystallize easily, so the negative pressure side shouldn’t get clogged. Besides, this is a double-flange design. There are also pressure tapping isolation valves for double flanges, right?
I agree with the view on the second floor; this situation occurs if the density changes due to process reasons. You can use a double-flange capillary differential transmitter to check whether there is a leak in the negative-pressure capillary.
Well, I suggest that if it’s possible, measure the gas phase pressure inside the container; that could also work, right?
Let’s talk about the properties of the medium being tested
The liquid phase is relatively clean and less likely to get clogged, and the gas phase is even less likely to get clogged; in my opinion, this is caused by changes in the density of the medium. Top floor 2!
Is there a way to clear the slots and check if it’s at zero?
Hehe. Then your jurisdiction becomes quite problematic. In my experience, it’s a problem with the manufacturing process. But the process won’t admit it’s his problem. Every time, it requires you to keep disassembling and keeping checking. Until one day, because he removed too much and damaged it, he came over and said, hahaha. I just said it must be something wrong with your gauge; look, look, and he even argued with me.