Pressure difference before and after the valve issue
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Can a large pressure difference before and after the valve prevent it from opening?
Yes, an excessive pressure difference can cause this situation
This post was last edited by ylb913 on 2016-1-4 at 08:23. Control valves are generally used for pressure reduction, as too large a pressure difference means that the valve cannot be closed any further once it reaches a certain degree of closure. I’ve encountered this situation before, with a control valve that didn’t have a positioner. I asked them to use one with a locator at that time, and that solved the problem. Previously they had experimented with feeding instrument air directly past the locator, and closing the valve worked fine. This kind of situation can occur with gate valves and similar devices.
1. For valves such as gate valves and ball valves, the pressure difference acts on the valve core, causing it to fit tightly against the valve groove and seat, which increases the frictional resistance. When the force (or torque) applied to open the valve is less than the frictional force (or torque), it becomes difficult to open the valve. 2. In the case of high-pressure valves, depending on the direction of fluid flow, if the pressure difference acting on the cross-section of the valve core is in the opposite direction to the force required to open the valve, more external force must be applied.
First, it’s necessary to determine whether it is of the open-flow or closed-flow type. If it flows away, a situation where it cannot be shut off will occur. This is due to the number of springs and the coefficient of each spring. If it is a flow blockage, it will not be possible to open it. Therefore, certain factors are taken into consideration when selecting actuators; for example, Chuanyi’s valves – HAR2 and HAR3 – take into account the pressure required for closing
We currently have a ball valve that fails to open when there is a high pressure difference; it functions normally when there is no pressure. This kind of situation has not occurred with the same process before. This situation only started appearing recently; I don’t know what’s going on
Yes, there is a range within which the pressure difference before and after the control valve is acceptable.
There is one parameter in valve design: the design closing pressure difference. This needs to be provided when applying for process funding.
What kind of valve are you? Control valve? Switch to a two-seater, please
Ball valves and control valves – these have been used here since the factory was established. . This problem only appeared recently