One of the faults, the valve does not pass. The reasons are:

1 The control channel is blocked by debris (small channel, easy to block);

2 The piston is stuck in the highest position due to rust stains; although the upper part is stressed, it cannot move downwards and cannot open the main channel.

Therefore, the filter must be installed before the piston pressure reducing valve; for the newly installed or long-term decompression valve, we must open the inspection and cleaning.

The second failure, the valve through, can not afford decompression. The reasons are:

1 The piston stuck in a certain position (not the highest position);

2 The main valve stem is stuck at a position (not a close position) in the pilot hole of the cylinder plate;

3 The main valve disc spring rupture or failure;

4 The valve of the pulse valve is stuck in a certain position (not the close position) in the valve seat hole, so that the piston is always under pressure;

5 between the main valve seat and the main valve seat sealing surface, there is dirt stuck or nick;

6 Diaphragms fail due to fatigue or damage.

For pressure relief valves, special emphasis should be placed on regular inspections. If it is found that dirt, rust stains should be removed in a timely manner; piston ring damage should be updated; spring failure should be replaced by available; if the sealing surface is not close, should be re-grinding; diaphragm does not work to replace; use, such as to confirm the valve handle Coarse, sanded with sandpaper.

The third failure, the pressure behind the valve can not be adjusted. In addition to the above reasons, there are:

1 failure to adjust the spring; 2 cap leaking joints can not maintain pressure.

This also depends on timely inspection and treatment.

In addition, there is also a phenomenon that the pressure pulse behind the valve fluctuates and is extremely unstable. This is because the difference between the input medium and the output medium is too large. Therefore, the valve with the equivalent valve diameter should be selected again. There is also a cause of instability in the pressure behind the valve is that the adjustment spring is not properly selected; a nominal pressure relief valve, there are several adjustment springs, such as a nominal pressure of 16 kg / square centimeter, the adjustment spring has 1-3 Kg/cm2, 2-8 kg/cm2, 7-11 kg/cm3, if the pressure behind the valve is only 1-3 kg/cm2, and the spring is 7-11 kg/cm2. The pressure on the valve will not be adjusted.