Spraying Systems Piston-Type Pressure Relief/Regulating Valves Bypasses excess liquid. Adjustable to maintain control of line pressure at any pressure within the valve's operating range. Selected pressure setting firmly held in place by lock-nut. Extra large valve passages to handle large flows. Features: Removable bonnet for servicing unit without removing valve from line. Details: Inlet & Pipe connections: 1/2". Material: Brass. Pressure Range: 150 PSI (10 bar).