VALVE UNIT Russian patent published in 1998 - IPC

FIELD: devices for closing pipelines with working medium flows. SUBSTANCE: valve unit includes body with inlet and outlet ducts, first seat made in body, cover, piston type spring-loaded closure, unloading passages mutually connected through pilot valve. One of unloading passages is joined with atmosphere or with other unloading passage. The last is connected with inlet duct of body. Closure has bypassing ports. Second seat is arranged in outlet duct of body, it is provided with sealing member and engages with lower portion of closure. EFFECT: enhanced reliability of valve operation. 5 cl, 1 dwg