Observe the overall design. Hale relief valves are constructed out of corrosion-proof bronze and manufactured in a butterfly style. Butterfly valves vertically position a thin rotating disk between two connecting points. The disk spins in one direction on a continual basis to provide valve pressure in a singular route.
Examine the gauge. The valve gauge must read between 75 and 250 psi. All Hale relief valves are initially set at 125 psi before being conjoined with any outside pressure system.
Spin the handwheel. Hale relief valve handwheels -- or knobs -- fully open or close any pressure system with a maximum of 10 full rotations.