Double-plate gate valve
Thread Content
Are the pressure relief holes of double-disc gate valves located on the high-pressure side or the low-pressure side? Are there any clear standards that address this issue? The common practice is to install it on the high-pressure side, but the theoretical basis for this is insufficient.
This post was last edited by WQC on 2010-6-5 at 19:42. According to the arrangement of their sealing surfaces, gate valves can be divided into wedge-type gate valves and parallel-plate gate valves. Wedge-type gate valves can further be classified into single-plate type, double-plate type, and elastic-plate type； Parallel plate gate valves can be divided into single-plate type and double-plate type. Based on the position of the valve stem threads, they can be divided into open-ended gate valves and blind gate valves. The purpose of the pressure relief hole is mainly to release the pressure inside the valve chamber; if the pressure becomes too high, it can damage the valve body. Therefore, I think it should be located between the two valve plates – I’m not sure if that’s correct.
Generally, during installation, the pressure relief hole should be placed on the high-pressure side
This post was last edited by yjfxy928 on 2010-6-5 at 17:45. Double-disc gate valves are generally of the wedge-type or parallel type; when the valve is closed, the pressure of the medium increases, which raises the sealing pressure required to open the valve, resulting in an excessively high opening torque； Prevent deformation or damage to the valve stem when it is opened ； Prevent the valve disc from deforming or being damaged ； It is safer to first open the pressure relief valve to release pressure, and then open it afterward! Therefore, it should be installed on the high-pressure side; if the medium is toxic, a small tube should be connected from the high-pressure side to the low-pressure side, with a small valve placed in between to be opened in order to achieve pressure relief! The hole between the two valve flaps should be a pressure testing hole, which is also used to drain the medium ； Theoretically, applying pressure from the middle hole can also achieve balance on both sides, but it is quite costly to implement in practice! In my opinion, everyone should leave more comments!
Is the hole between the two valve flaps the pressure testing hole? ? I don’t understand, please explain! Oh my God, the problem from 2008 has finally been solved today!
Reply to 5# liuxskysdo: After the gate valve is manufactured, a pressure test is usually carried out. First, the valve is closed, and then pressurized fluid is introduced through a small opening to check the degree of leakage at both sealing surfaces. In this way, testing a gate valve is the simplest!