Sump pressure fails to build to minimum (typically ~40–65 psi on many screw units, verify nameplate) causing poor lubrication and slow separator flow.
1
MPV spring weak or seat worn
Rotary screw
CheckSump pressure stays near line pressure even at low demand; disassemble and inspect (LOTO, 0 PSI).
FixRebuild with OEM kit (spring + seat + seals).
SafetyLOTO and verify 0 PSI before opening.
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2
Debris holding valve open
Rotary screw
CheckInspect for metal shavings or separator element debris on the seat.
FixClean valve; investigate upstream contamination source.
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3
Check valve disc cracked or hinge pin worn
CheckVisual inspection after removal.
FixReplace check valve.
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4
Sensing line to MPV plugged
Rotary screw
CheckVerify sensing/pilot line is clear and correctly routed.
FixClear or replace line.
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Safety
Lockout/tagout before opening enclosures. Verify zero energy. Bleed system pressure before opening any pneumatic connection.