One of the faults, the valve barrier. The reasons are as follows: ①The control passage is blocked by debris (the passage is small and easy to block); ② The piston is jammed in the highest position due to rust stains; although the upper part is forced, it can not move down and can not open the main passage. Therefore, the piston valve must be installed before the filter; for new installation or long-term deactivation of the valve, be sure to open the inspection and cleaning. Fault two, the valve through, can not afford the role of decompression. The reason is as follows: ①The piston is stuck at a certain position (not the highest position); ② The valve stem of the main valve is stuck at a position (not the close position) of the guide hole of the cylinder disk; ③ The spring at the lower part of the main valve disc breaks or fails; ④ pulse valve stem in the seat hole at a certain position (not in close position) stuck, so that the piston is always subject to pressure; ⑤ between the main valve flap and the main valve seat sealing surface, there is dirt stuck or Scotch marks; ⑥ diaphragm failure or damage due to failure. For the valve, with special emphasis on regular inspection. If found dirt, rust stains to be promptly removed; piston ring damage should be updated; spring failure to be replaced by available; sealing surface if not close, should be re-grinding; diaphragm ineffective to be replaced; Coarse, sandpaper application. Third, the valve pressure can not be adjusted. In addition to the above reasons, there are: ①adjust the spring failure; ② cap joints leak, can not maintain pressure. This also depends on timely inspection and treatment to prevent. In addition, there is another phenomenon, that is, the pressure pulse after the valve fluctuations, very unstable. This is the difference between the input medium and the output medium is too large, it should reselect the valve diameter of the valve. There is also a cause of instability after the valve pressure is due to improper adjustment of the spring; a nominal pressure relief valve, there are several regulating spring, such as the nominal pressure of 16 kg / cm, the adjustment spring there 1-3 Kg / cm2, 2-8 kg / cm2, 7-11 kg / cm2 three, if the valve pressure after only 1-3 kg / cm2, while the spring is 7-11 kg / cm2 Species, the pressure on the valve after the tune is not allowed. More Keywords Search: Valve