Humphrey 590A Series Air Piloted Valves have ¾ “ NPT pipe port and 5/8″ orifice size allowing for very high air flow rates. The exclusive diaphragm-poppet design originated by Humphrey consists of two specially contoured diaphragms mounted on an axial stem within a full-ported, full-orifice valve body. This classic design is simple, seals tight, requires no lubrication and is highly reliable and robust. The 590A is available in 2 way and 3 way configurations. Ideal medias include air, vacuum, liquids or other gases.