Castair CA12 — Genie Unloader Compression Fitting (1/2" x 3/8")
The Castair CA12 is a compression fitting in Castair's Genie unloader-type check valve series — specifically a 1/2-inch inlet by 3/8-inch outlet compression fitting. This type of fitting is used in the unloader circuit of air compressors, where it serves as a check valve that allows air to release from the pump head when the motor shuts off (enabling the next unloaded start), while preventing reverse flow from the tank back into the pump. The CA12 uses a compression inlet fitting for direct connection to copper discharge tubing.
From Castair's published check valve data: The CA12 is listed under "Genie Unloader Type" with Comp. fitting inlet, 1/2" x 3/8" inlet-outlet sizing.
What Genie Unloader Fittings Do
Genie unloader check valves serve a specific function in piston air compressors:
- Check valve function: Prevents backflow from the tank to the pump head — critical for preventing the motor from having to start against full tank pressure
- Unloader function: When the motor stops (pressure switch opens), the unloader releases trapped pressure from the pump discharge side — the next motor start is fully unloaded
- Compression inlet: The 1/2-inch compression inlet mounts directly to copper discharge tubing without requiring pipe threads on the tube end
A failed or leaking genie unloader fitting is a common cause of compressor problems — symptoms include the motor struggling to restart, cycling on the overload protector, or continuous hissing from the pressure switch unloader port after shutdown.
Castair Genie Unloader Fitting Series
| Part # | Inlet Style | Inlet-Outlet Size |
|---|---|---|
| PA6 | NPT female | 1/4" x 1/4" |
| CA6 | Comp. fitting | 3/8" x 1/4" |
| PA12 | NPT female | 3/8" x 3/8" |
| CA12 | Comp. fitting | 1/2" x 3/8" |
CA = compression fitting inlet; PA = NPT female inlet. The outlet side connects to the pressure switch unloader port or tank check valve plumbing.
When You Need This Part
- Your Castair compressor is struggling to restart — the motor hums and trips the overload, suggesting the pump is starting under pressure
- You hear continuous hissing from the area of the pressure switch after the compressor shuts off — the unloader fitting may be stuck open
- You're rebuilding or servicing a Castair commercial or industrial compressor and replacing all check valve and unloader components
- You're building a custom compressor around a Castair pump and need the unloader fitting for the pressure switch circuit
Installation Notes
- Match the fitting size to your discharge tube OD — the CA12 is 1/2-inch compression inlet
- The 3/8-inch outlet connects to the pressure switch unloader port — verify thread size and type on your pressure switch
- Compression fitting installation requires a square-cut, clean tube end
- If the compressor has been running with a leaking unloader, inspect the pressure switch unloader port for damage
Why Buy From Air Compressor Factory Direct?
We stock Castair replacement parts and can help you diagnose compressor problems and identify the correct unloader fitting for your machine. Free shipping on qualifying orders. Free tech support at 866-217-0063. Full manufacturer warranty on genuine Castair parts.
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