The tension of the spring on the brass disc causes "self-lapping" of the brass disc face against the steel body plate, honing the brass disc, preventing leakage from developing.

Valves are assembled with three capscrews and nuts making it easy to open and repair.

Valves are available with a "dead-man" control spring for the handle.

Valve has four ports:

• One air inlet
• Two working ports
• One exhaust port