Valve closed. With the blue handle pushed inward, air pressure at the inlet is blocked. Pressurized air remaining down- stream is exhausted through the exhaust port.

Valve activated. With the blue handle pulled outward, inlet air passes through the metered orifice (size set by adjusting screw) and begins to pressurize the outlet. High pressure inlet air on the top of the fly back piston prevents the spring be hind it from sliding the piston along the spool. The position of the piston keeps the outlet blocked from the main flow of inlet air.

Valve open. Air through the metering orifice gradually in creases the pressure on the spring side of the fly back piston. At about 25 psi less than inlet pressure the force on the piston is enough to slide it along the main spool. Inlet air then flows freely to the outlet.