What failures may happen to the forced Valve itself and how to deal with them?

The forced valve is opened and closed by the air source pressure pushing the piston. Its faults include the faults in the cylinder and the valve body.
The faults in the cylinder are mainly caused by the slow switching action, the valve is not easy to open or close badly. This is caused by low gas source pressure, dirty gas source or excessive pipeline resistance. It is also possible that the piston ring is worn and the amount of lubricating oil is too small, which causes air leakage of the piston. When the sealing packing is too tight, it will also cause the phenomenon of slow movement. In order to prevent air leakage, in addition to checking whether the seal is in good condition frequently during overhaul, you should also pay attention to keeping enough lubricating oil in the cylinder. Rust on the inner wall of the cylinder or foreign matters entering may also cause the phenomenon of jam, causing the forced valve not to move.
The main failure in the valve body is the phenomenon that the valve cannot be closed due to the untight sealing surface between the valve top and the valve seat. The most common is that the O-type rubber sealing ring falls off. This is mainly related to the unclean bonding surface and the poor quality of the adhesive. In addition, there is foreign matter at the valve seat; the concave-convex spherical gaskets at both ends of the valve stem and the valve top are screwed too dead or too loose; the fixed nut is not tightened, which causes the valve top to loose; the bending of the valve stem can cause the phenomenon of untight closing of the valve, etc.