Ingersoll Rand inlet valve (UP6 / R-Series)

Piston-actuated poppet inlet valve with integral check, sitting between the intake filter and the airend.

Also called: intake valve UP6 · unloader assembly

How it works

1SV control air drives the piston to open the poppet; the poppet spring plus a check disc close it on unload/stop. On modulating R-Series a modulation valve feeds a variable pressure to the same actuator for part-load throttle.

Specifications

Rebuild kit

Seal/spring kits per frame (e.g. 39911599-family kits)

Pilot

1/4" line from 1SV via inline orifice

Parts you can order

• Ingersoll Rand (OEM)

  Inlet valve repair kit

  Serial-specific (e.g. 22203843 family)

  $90 – $340

Field test procedure

1. Check the small orifice/filter in the pilot tee — a classic IR no-load cause.
2. Verify the poppet snaps shut once the pilot is vented.

Symptoms & probable causes

• Slow to build pressure
  Partly opening poppet or restricted pilot.
• Oil carryover out the intake
  Failed check disc.