Rolair 131BIG Pilot Unloader Valve For Air Compressors

The 131BIG RolAir Pilot Unloader Valve is the OEM replacement part that drives unloading and idle control on RolAir constant‑run compressors. As part of RolAir’s piloted unloader valve assembly, it combines a pilot valve and an unloader valve to allow the engine to idle and the pump to unload when the discharge pressure reaches the unload setting. A notable feature is its large 1-inch (25 mm) pilot port, which facilitates integration with larger pilot lines. The valve is designed for RolAir gas- and electric-powered units and is commonly supplied as a direct replacement for models requiring the 131BIG specification, including installations associated with the 7722HK28/20 family. Typical top-end pressure settings for units using this valve are in the 110–135 psi range, aligning with RolAir’s standard unload thresholds. This part is documented in RolAir’s official literature and parts catalogs as VALVE, PILOT UNLOADER, 131BIG, confirming its role in controlling the unloading sequence and engine idle, reducing wear and oil consumption by equalizing pressure between the pump and check valve.