Valve plate / reed valve service
Diagnose and replace reed and disc valves — the #1 cause of lost CFM on recip pumps.
This guide is general field reference for trained, qualified service technicians. It is not a substitute for the original equipment manufacturer's service manual, applicable codes (NEC, OSHA, ASME, local), or the judgment of a licensed professional. Procedures, torque values, pressures, refrigerants, and safety requirements vary by make, model, jurisdiction, and revision. Always verify against current OEM documentation and follow your employer's safety program. Working on compressed-air, electrical, pressure-vessel, and refrigerant systems can cause serious injury or death. By using this guide you accept all risk; AirCompDX and its authors disclaim all warranties and are not liable for any damage, injury, loss, or code violation arising from its use.
LOTO and bleed to 0 psi. Head surfaces are sharp — wear gloves when handling valve plates.
- Socket set
- Torque wrench
- Feeler gauge
- Flat lapping plate or plate glass + 600-grit
- OEM valve plate kit or reed set
- Head and valve-plate gaskets
- 1Confirm valve failure
Run a pump-up test — a healthy pump fills its tank within 10% of the published rate. >25% slow with no audible leaks and a hot head = valves.
- 2Cool, LOTO, depressurize
Let the head sit below 120°F. Apply LOTO and bleed the tank fully.
- 3Remove head
Cross-pattern loosen, lift straight up. Note: intake valves face the suction side, discharge valves face the cooler/manifold side.
- 4Inspect
Hold reeds to a light — any curl, chip, or carbon = replace. Disc-style valves: check seat for pitting; lap the seat on glass + 600-grit if light pitting only.
- 5Replace valve plate
Most modern pumps sell the plate as a sealed assembly — do not disassemble. Reuse dowels, new gaskets dry, torque head in cross pattern in 3 passes.
- 6Run-up
Restore power and run a pump-up test again to confirm CFM recovery and head temp returns under 350°F at full load.