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SECTION 9
MINIMUM PRESSURE/CHECK VALVE
MINIMUM PRESSURE/CHECK VALVE
- This device maintains minimum pressure within the air/oil
reservoir, thus insuring (cooling/lubricating) oil injection flow into the compressors. It also serves as a
check valve to prevent back flow of compressed air flow from the customer’s piping or pipe network back
into the compressor package when the compressor is not active. The spring-loaded piston does not allow
the discharge of compressed air from the air/oil reservoir until the compressor builds up reservoir
pressure exceeding 60 psig. Beyond this pressure level, the valve remains fully open.
The valve does not require maintenance or adjustment. If the valve fails to function, check the valve stem
O-ring for sealing, valve orifices for restriction, or valve and valve seat for burrs and dirt. Repair kits are
available from your local authorized Gardner Denver distributor.
Before servicing the minimum pressure valve, always stop the unit, release air
pressure, lockout and tagout the power supply to the compressor package.
Failure to release pressure or properly disconnect the power may result in
personal injury or death.
NOTICE
Working spring within valve body is under tension. Failure to relieve spring
tension gradually may cause serious injury upon cap removal.
Minimum Pressure/Check Valve (MPV) Inspection:
1. Be sure the unit is completely off and that the oil sump is depressurized – including pipe works
between MVP and (external) isolation valve.
2. Disconnect, lockout and tagout power supply to the compressor package.
3. Tighten nut (12) on the MPV frame (5) – this compresses the internal components prior to removal.
4. Unscrew bolts fastening MPV frame (5) to the sump housing and remove MPV assembly.
5. Remove snap ring (8) restraining internal components to the cover.
6. Remove internal component assembly (1-4, 6-11, 15) away from MPV frame (5) and inspect or
replace components