What the valve does
It opens to let air in when the compressor loads and closes to unload it. It works with the control system, so its behaviour affects pressure stability and energy use.
Symptoms of a problem
Common signs:
- The compressor will not load or unload correctly
- Pressure swings or slow loading
- Oil blowing back through the intake
- Sticking, leaking or noisy operation
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- The existing part number and any superseded number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 control side too
Valve symptoms may come from the actuator, the solenoid, the control air or the controller setting rather than the valve itself. We check the control arrangement so a good valve is not replaced or a new valve is not fitted onto the same fault.
Before you order
Confirm that the valve type, actuation and mounting match your machine exactly.
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 an inlet valve be repaired?
Often a repair kit can be used, depending on the valve and the damage. We help you decide between a repair kit and replacement.
What causes an inlet valve to stick?
Contamination, wear, dirty control air or a failed actuator are common causes. We look at the cause, not only the symptom.
Does the valve affect energy use?
Yes. A valve that does not unload properly causes the compressor to use more power than necessary.
Field guide
Inlet and unloader valves: when the machine will not load or unload
The inlet valve opens to let the screw compressor load and closes to unload it. On piston compressors, unloaders hold suction valves open or vent the head so the motor can start without load. When these valves stick, leak or lose their control signal, the symptoms look like a much bigger fault.
| Symptom | Possible valve cause |
|---|---|
| Machine runs but will not load | Inlet valve stuck closed, failed loading solenoid, control air leak |
| Machine will not unload, safety valve lifts | Inlet valve stuck open, unloader failure |
| Oil mist from the air filter at stop | Inlet valve not closing fully; check valve or blow-down fault |
| Piston motor struggles to start | Unloader not venting the head or holding valves |
| Pressure overshoot | Slow-acting valve, worn seals or spring |
Most inlet valves can be rebuilt with a service kit of seals, springs and a piston or plate. Check the control circuit and solenoid first: a valve that never receives its signal will never move. After any repair, check load, unload and blow-down timing under normal operation.
What to send for a quotation
- Compressor make, model and serial number.
- Photo of the inlet valve and any part number.
- Symptoms and controller messages.
Send it through find my part or the spare parts enquiry, or call +91 99590 60718 or +91 92468 88812.