Humphrey 250A Series Air Pilot Valves have 1/4 NPT ports and orifice size. 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, requires no lubrication, seals tight and is highly reliable. The valves are available in 2way, 3 way and 4 way models.  Ideal medias include air, vacuum,   other gases or liquids.