SHUTOFF VALVE Russian patent published in 1997 - IPC

FIELD: valving. SUBSTANCE: shutoff valve has housing with inlet and outlet passageways connected with the inlet and outlet spaces, respectively, seat, normally open valving member mounted inside the inlet space, and drive for its moving comprising piston with double-sided rod and two floating rings-shaped pistons mounted in the bore in the housing behind the seat to form a space between the seat and piston, control space, and additional control space. The control space and additional control space are in communication with a control system through control passage and additional control passage, respectively, that are connected with the supply passage coming from inlet space. One of the ends of the double-sided rod passes through the opening in the seat and rigidly connected with the valving member. The second end of the rod passes through floating ring-shaped pistons and enters the outlet space. The double-sided rod is provided with axial and radial passageways that communicate the space between the seat and piston with the outlet space. The stroke of the additional ring-shaped piston is arrested with an additional stop mounted at the second end of the double- sided rod. The magnitude of the stroke is greater than that of the floating ring-shaped piston whose stroke is arrested with a stop in the housing. The outer diameter of one of the floating pistons is greater than the outer diameter of the other one. EFFECT: enhanced reliability. 2 cl, 1 dwg