Problems during valve pressure testing
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The two valves were connected and pressure tested to check for internal leaks. Both valves were closed, and a pressure of 15 kilograms was maintained. Then, the valve on the side far from the pressure gauge was opened; why did the pressure on the gauge drop, even though the valve on the side near the gauge remained closed? The pressure dropped to 2 kilograms, but after 30 seconds it rose back to 9 kilograms. It seems that there’s a valve closed near the pressure gauge; if the valve far from the pressure gauge is opened, the pressure gauge shouldn’t change, right?
According to your description, when both valves are closed and a pressure of 15 kilograms is maintained, the pressure gauge should stay at 15 kilograms without any drop in pressure. However, when you open the valve on the side away from the pressure gauge, the pressure drops to 2 kilograms, and then rises back to 9 kilograms. Possible reasons include the following: 1. The valve on the side away from the pressure gauge is not fully closed: Please check whether the valve on the side away from the pressure gauge is fully closed; if it isn’t, it will cause the pressure indicated by the pressure gauge to drop. 2. There is internal leakage in the valve located near the pressure gauge: Although you mentioned that the valve on that side is closed, internal leakage may still occur; that is, some pressure continues to leak even after the valve is closed, resulting in a drop in pressure on the gauge. 3. Problems with the pressure gauge itself: The pressure gauge may be faulty or inaccurate, resulting in incorrect pressure readings. In response to this situation, it is recommended that you check whether both valves are fully closed, and carefully inspect the valve on the side near the pressure gauge for any internal leaks. If the problem persists, consider replacing the pressure gauge or seeking professional assistance for repairs. .
Thank you for the response. However, there is no internal leakage in the valve. A pressure test was conducted using water at a pressure of 15 kilograms. With valves A and B closed, the blind plate on the left side was removed; after valve B was opened, the pressure on the gauge gradually decreased. When the water between valves A and B was completely drained, the pressure dropped to 2 kilograms. After 30 seconds, the pressure began to rise again (without any recharging of pressure), eventually reaching 9 kilograms. The pressure remained stable for 5 minutes without dropping, which indicates that there is no internal leakage in valve A. The testers said this phenomenon has always been present, but they couldn’t provide an explanation
Based on your description and the method of pressure testing, the specific reason is that when pressure is applied, both A and B are in the closed state; there is a space between A and B that contains no water. When valve B is opened, water fills that space between A and B, which is why the pressure indicated by the gauge decreases. Once that space is filled, the pressure gradually rises again, but the overall pressure will still be lower.
The descriptions before and after are inconsistent; it’s unclear what your pressure testing process is
I just couldn’t figure out how to conduct the pressure test; even after reading it, I’m still completely confused
That’s correct; it should be that way. The reason for the pressure drop is the presence of space, while the reason for the increase in pressure is that the pressure returns once the space is filled