Chicago Pneumatic 1" x 3/4" NPT Check Valve - 1312100172
A compressor check valve is a one way valve designed to let the compressed air go from the compressor pump into the tank. Check valves allow the air to flow in one direction only, preventing backflow from the tank to the pump. A properly functioning check valve will prevent the compressor from having to start against backpressure, which can otherwise damage the motor and cause strain on the pump.
If air is leaking out of the pressure switch when the compressor is off, the check valve typically needs to be changed out. This results in debris or dirt causing the valve to stay open, letting air from the tank back through the small copper unloader line that connects to the pressure switch. If air leaks from the pressure switch when the compressor is shut off, you should replace the check valve rather than the pressure switch.
The Chicago Pneumatic 1312100172 compressor check valve can also be changed out annually as a preventive maintenance item to help lengthen the life of the motor and prevent costly air leaks.
You may see this valve listed in your manual as 1312-1001-72 or 1312 1001 72. This is commonly used on Quincy, Atlas Copco, and BelAir compressors and will fit any air compressor that uses a 3/4" NPT fitting from your discharge tube and a 1" NPT fitting on your tank.
This check valve will fit the following piston/reciprocating compressors from Chicago Pneumatic: