ROLAIR PS3535 Air Compressor Pressure Switch

PS3535 four-port air compressor pressure switch provides automatic on/off control by sensing system pressure and venting via an unloader valve. It uses four 1/4" NPT ports (inlet, outlet, and two control/relief connections) to simplify plumbing on most single-stage compressors. Available configurations include the standard 125/95 psi cut-in/cut-out range and the higher-pressure 175/140 psi variant (often labeled PS3535HP), both featuring an adjustable relief valve and an integrated unloader function to vent the head at shutdown and speed restart. Variants are sold under Furnas Electric / Hubbell branding and as Rolair PS3535HP, reflecting the same four-port architecture across different pressure ranges. Widely used in residential and light-commercial compressors, this switch helps maintain steady pressure while protecting equipment by cycling the motor only when the set pressure is reached.