What could be the reason of air compressor first stage high discharge pressure?
Firstly check second stage suction valve. Frequently such problem happens with mentioned valve leaking high pressure air back to first stage.
In addition to the above, if the air compressor is a single-piston type, i.e. with the same piston for both stages, leaking piston rings of may let the high pressure air into the first stage. It will cause the first stage safety valve to pop-up.
The troubleshooting procedure, in this case, will be as follows:
- Check the second stage suction valve(s), replace if necessary
- If high first stage pressure persists after the first step, pull up the piston and check piston rings. Replace as necessary.
Check the second stage suction valve positioning. Sometimes, the inexperienced crew installs them upside down.
In such a case the air from the first stage is unable to get into the second stage causing the first stage safety valve to popup.
