Gardner Denver L4-5C Original User Manual page 59

MINIMUM PRESSURE VALVE
Minimum Pressure Valve (MPV) Inspection – This device has no user-serviceable or repairable
components. If it fails to maintain adequate minimum pressure (60 psig) or fails to check the backflow of
system compressed air after compressor stoppage, replace it as follows:
Air/oil pressure will cause severe personal injury or death. Shut down
compressor, relieve system of all pressure, disconnect, lockout and tagout
power supply to the starter before removing valves, caps, plugs, fittings, bolts
and filters.
1. Be sure the unit is completely off and that no air pressure is in the oil reservoir and in the air cooled
after cooler. Close the service valve.
2. Disconnect lockout and tagout the power supply to the starter.
3. Unscrew the minimum pressure valve assembly from compressor housing and remove.
4. Inspect the valve seat surface on the valve itself. Cleanse or replace. Also inspect the mating seat
area on the host manifold. Cleanse or replace manifold.
5. Assemble the MPV assembly into the host manifold.
6. Run the unit and check for leaks.
7. If a new MPV has been fitted, its proper setting must be adjusted:
a. Make sure the site pipe system has a means to vent the compressor air to atmosphere with a
valve. If this is not available, temporarily fit a 1/2" to 3/4" ball valve to achieve so.
b. Start the compressor and monitor the wet (B1) and dry (B2) sump pressure sensors at the
GD Pilot controller display.
c. Open the site vent valve to limit the dry sump pressure to about 40 psig (2.8 bar)
d. Loosen the jam nut on the TMV adjusting stem and screw it in until the wet sump reaches 60
psig (4.1 bar).
e. Tighten the jam nut on the TMV adjusting stem.
f. Close the site vent valve.
Figure 9-3 Minimum Pressure Valve and Seat
13-25-629 v03 Page 59