Common Failures of Automatic Valves

Common Failures of Automatic Valves

Failure number one: the valve is stuck. The reasons include:

1. The control channel is blocked by debris (the channel is small so it’s prone to blocking)

2. Due to rust, the piston is stuck at the highest position. Although it’s impacted at the upper part, it can’t move down, so the main channel can’t be opened.

Therefore, filters must be installed in front of the sanitary pressure relief valve. For pressure relief valves that are newly installed or not in use for a long time, be sure to disassemble them to check and clean.

Failure number two: the valve is straight-through, and doesn’t have a pressure-relieving effect.

The reasons include:
1. The piston is stuck at a certain (not the highest) position.

2. The valve stem of the main valve is stuck at a certain (not the sealed) position of the guide hole of the cylinder disc.

3. The spring at the lower part of the valve flap of the main valve breaks or is no longer effective.

4. The valve stem of the pulse valve is stuck at a certain (not the sealed) position of the valve seat hole, which causes the piston to be under constant pressure.

5. There is dirt or scratch between the two sealing surfaces of the main valve flap and main valve seat.

6. The diaphragm fails due to fatigue or damage.

For pressure relief valve, be sure to check regularly. If dirt and rust are found, they must be removed in a timely fashion. The damaged piston ring should be replaced. A dysfunctional spring should be replaced with a functional one. If the sealing surface is not tight, it should be ground again. The ineffective diaphragm should be replaced. If the valve stem is confirmed to be quite thick, it should be polished using abrasive paper.

Failure number three: the valve pressure can’t be regulated.

The reasons include:

1. The regulating spring fails.

2. There’s leakage at the cap seam, so the pressure can’t be kept.

In addition, there’s a phenomenon: the pressure pulse after the valve fluctuates, which is very unstable. This is because the amount of difference between the input medium and output medium is too big. We should reselect valves with approximately the same diameters.