Fault one: the valve is not through. The reasons are as follows: (1) the control channel is blocked by the sundries (the passage is small and easy to be blocked); and the piston is stuck in the highest position because of rust stains; although the upper part is stressed, it can not move down and can not open the main channel. Therefore, before the piston pressure relief valve must be installed filters, for newly installed or long-term discontinued pressure relief valve, must be disassembled for inspection and cleaning.

Fault two: Valve straight through, do not play the role of decompression. The reasons are: (1) the piston is stuck in a certain position (not the highest position); (2) the main valve handle is stuck in a position (not close to the close position) of the steering hole of the cylinder disc; (3) the spring of the main valve disc is broken or invalid; (4) the pulse valve handle is stuck in a certain position (not close to the close position) in the seat hole, so that the piston is always subjected to pressure; 5 Between the valve and the two seat cover of the main valve seat, there are dirt stuck or notched, and the diaphragm is out of order due to fatigue or damage. For pressure relief valves, special emphasis should be placed on periodic inspection. If it is found that dirt and rust stains should be removed in time; the damage of the piston ring should be updated; the spring failure should be replaced to available; the sealing surface, such as untightness, should be regrinded; the diaphragm should be replaced; the use of sand paper, if used, is used for grinding.

Fault three: the pressure can not be adjusted after the valve. The reasons are as follows: (1) adjusting the spring failure; (2) the leakage of the cap joint can not keep the pressure. This also depends on timely inspection and treatment to prevent it. In addition, there is another phenomenon, that is, the pressure pulse fluctuation after the valve is very unstable. This is because the difference between the input medium and the output medium is too large, so the valve with equal valve diameter should be re selected. Another cause of pressure instability after the valve is the improper selection of the spring; a pressure relief valve, which regulates the spring has several kinds, such as the nominal pressure of 16 kg / sq cm, and the adjustment spring is 1-3 kg / sq cm, 2-8 kg / sq cm, 7-11 kg / sq cm, and three kinds if the pressure is after the valve. It only needs 1-3 kilograms per square centimeter, while the spring is 7-11 kilograms / square centimeter.

Fault four: one of the failures of the spring type safety valve, and the leakage of the sealing surface. The reasons are as follows: (1) there are sundries between the sealing surfaces; This kind of fault depends on regular maintenance to prevent. Two of the fault, the sensitivity is not high. The reasons are as follows: (1) spring fatigue; (2) improper use of springs. Spring fatigue, no doubt should be replaced. Improper use of springs is a spring safety valve which does not pay attention to a nominal pressure. There are several pressure segments, and each pressure section has a corresponding spring. If the pressure of the nominal pressure is 16 kg / sq cm, the pressure is 2.5-4 kg / sq cm, and the spring of 10-16 kg / sq cm is installed, although it can also be opened, but it is insensitive and insensitive.

Fault five: the common faults of check valves or check valves are as follows: (1) the disc is broken; The cause of the valve disc breaking is that the pressure of the check valve is in a state of close balance and mutual "sawing" before and after the check valve, and the valve flap is often flapped with the seat, and some brittle materials (such as cast iron, brass, etc.) are broken. The way of prevention is to adopt check valve with ductile material. The reasons for the backflow of the media are as follows: (1) destruction of the sealing surface; (2) inclusion of impurities. Repairing sealing surface and cleaning impurities can prevent backflow. The above description of common failures and prevention methods can only play an inspiring role. In actual use, there will be other failures. To be active and flexible in preventing the occurrence of valve failures, the most fundamental one is to be familiar with its structure, material and action principles.