CUT-OFF VALVE Russian patent published in 2000 - IPC

FIELD: valves used for restoring and operational check of wells. SUBSTANCE: cut-off valve includes body with axial duct and locking member arranged in body. Locking member is in the form of hollow differential piston with collet chuck in its lower portion. Valve is provided with guiding cylinder placed in body with formation of annular gap. Lock of collet chuck is mounted in lower portion of guiding cylinder with formation of sealed cavity. Locking member is mounted in guiding cylinder with possibility of reciprocation motion. Outer cylindrical surface of locking member is joined with inner surface of guiding cylinder. The last has openings in under-piston zone of locking member. In over-piston zone of locking member and in guiding cylinder also there are openings aligned in upper position of locking member. EFFECT: enhanced reliability of valve operation, possibility of its automatic operation in predetermined pressure range. 3 cl, 1 dwg