Common malfunction of self-operated control valve is pressure reducing performance failure and leakage between valve body and cover and end cover.When the breakdown of self-operated control valve in operation needs to be repaired, the self-operated control valve on both sides of the pressure reducing valve shall be closed first, and the by-pass tube shall work temporarily.At ordinary maintenance,self-operated control valve should be regularly inspected and repaired to reduce the incidence of failure.The contents of self-operated control valve regular inspection are: check the main valves, pulse valves, spring and diaphragm fatigue, cylinder wear or corrosion, piston ring loss of expansion, etc.