GATE VALVE Russian patent published in 1998 - IPC

FIELD: pipe-lines. SUBSTANCE: invention is meant for shut-off of pipe-line carrying fluids with high degree of fouling and high content of dust. Gate valve includes body with two mobile sealing seats placed at some distance one from another. Shutting off plates pressed against seats under action of restoring members are positioned between seats. Hydraulically controlled forcing out members uniformly located over periphery between protrusions of shutting off plates are used to press out shutting off plates. Forcing out members include outer cylinder with internal ring collar on free end, inner cylinder with external ring collar on free end and restoring member situated between outer and inner cylinders. Restoring member is manufactured in the form of unclamping spring or package of disc springs. Internal cylinder moves with regard to outer cylinder. Sealed ring chamber is formed between cylinders. Each forcing out member is fitted with two and/or three hydraulic circuits acting independently. Two of mentioned circuits are mounted for operation of one of them under stand-by mode when the other circuit operating under rated conditions fails. Each of these circuits are equipped with proper check valves or corresponding two-line two-position distributors. Third hydraulic circuit provided with two-line two-position distributor is used to remove fluid from ring chamber. EFFECT: improved functional reliability. 6 cl, 7 dwg