What the valve does
It holds a minimum pressure in the separator vessel for proper oil circulation and separation, and it prevents backflow from the air system when the compressor stops or unloads.
Symptoms of a problem
Typical symptoms:
- Slow pressure build-up or poor loading
- Oil carryover or high separator differential pressure
- Air flowing back when the compressor stops
- Leaks or noise at the valve
Identify the valve
To identify it:
- Compressor make, model and serial number from the nameplate
- The existing part number and any superseded number
- Photographs of the nameplate and of the installed part
- Operating hours and the fault or service interval that triggered the enquiry
Check the pressure setting
The opening pressure, flow capacity and connection must match the machine. A valve with the wrong setting can reduce performance or increase oil carryover, so we confirm the specification, not only the connection size.
Before you order
Confirm the opening pressure, size and seal material against the machine specification.
Ask for the supply status of the item: whether it is genuine, OEM-approved or an alternative, and whether it is in stock or must be sourced.
Check the lead-time basis and the warranty terms that apply.
Frequently asked questions
Can I replace just the seals?
In many designs a repair kit is available. We check whether the body is serviceable and recommend the kit or the full valve accordingly.
Why does the valve matter for oil carryover?
Without the correct minimum pressure, the separator cannot work properly and oil can pass downstream.
How do I know if it is leaking?
Backflow, slow loading or pressure loss after stopping are signs. A check by a technician confirms it.
Field guide
Minimum-pressure and check valves: small valve, important jobs
On an oil-injected screw compressor the minimum-pressure valve keeps enough pressure in the separator tank for oil to circulate during loading, and the check function stops system air flowing back into the compressor at stop. Check valves on piston compressors and in discharge lines prevent back-flow.
| Symptom | Likely cause |
|---|---|
| High discharge temperature at start or low demand | Minimum-pressure valve opening too early, poor oil flow |
| Oil carryover when the system is empty | Separator overloaded because minimum pressure not held |
| System air bleeding back at stop, oil from air filter | Check function leaking |
| Pressure drop across the valve, compressor running hot | Valve sticking partly closed |
| Hard restart on piston compressor | Discharge check valve leaking back into the head |
Service kits usually include seals, a spring and the valve plate or piston. Replace by the manufacturer's interval or when the symptoms appear. Never remove or bypass a minimum-pressure valve to "gain air": it protects oil circulation and separator performance.
What to send for a quotation
- Compressor make, model and serial number.
- Photo of the valve and any markings.
- Symptoms and when they occur (start, stop, low demand).
Send it through find my part or the spare parts enquiry, or call +91 99590 60718 or +91 92468 88812.