TWO-POSITION NON-RETURN VALVE Russian patent published in 1999 - IPC

FIELD: mounting systems used at emergency and repairing works in oil and gas wells. SUBSTANCE: valve includes housing, sleeve with seat arranged in cavity of housing, shut-off member, partition arranged under seat and having axial duct for rod of shut-off member. There is spring on rod between shut-off member and partition. Additional spring is arranged between partition and tail portion of rod. Springy lock is placed between housing and sleeve with seat. EFFECT: enhanced reliability of valve operation in emergency condition at cementing and generally overhauling wells. 2 dwg