Back-flow prevention valve
AssigneeSargent-Welch Scientific Company
InventorsDavid E. Hanson, Martin E. Frenkel
Life of this patent
Estimating the term…
Abstract
A back-flow prevention valve assembly is disclosed for use with a vacuum pump or the like and employs a valve element movable between positions opening or closing a passageway through the assembly. In the event of pump failure, a control valve, which is operated by fluid from the pressure side of the pump, vents ambient air behind the valve element to assist it in moving rapidly to the closed position to prevent backflow. After resumption of pumping, a controlled withdrawal of ambient air behind the valve element delays opening of the valve until the pump has created a sufficient vacuum to minimize influx of air upstream when the valve opens.
Claims27
A back-flow prevention valve assembly adapted for use with a pump for controlling the direction of flow of the fluid being pumped, said valve assembly comprising:
- housing means defining a fluid flow passageway therethrough;
- valve means carried by said housing means and movable between an open position permitting the flow of fluid through said flow passageway and a closed position blocking said flow passageway;
- said housing defining a chamber and said valve means including a plunger portion slidably received within said chamber and spaced a selected distance from the wall of said chamber;
- an actuating fluid passageway in said housing adapted at one end for communication with a fluid source having a higher pressure than the fluid being pumped and communicating at the other end with said chamber for applying pressure to said plunger portion to assist in moving said valve means to the closed position;
- and
- an actuating fluid control valve carried by said housing and having a fluid pressure access port for communication with high pressure fluid from the pump, said valve being movable by fluid pressure from the pump to close said actuating fluid passageway and movable upon the release of fluid pressure in the event of pump failure to allow actuating fluid into said chamber to force said valve means quickly into said closed position, and wherein said selected distance between said plunger and said cylinder is sufficiently small to restrict the passage of actuating fluid therebetween so as to delay movement of said plunger portion and said valve means to the open position upon restarting of the pump.
A back-flow prevention valve assembly adapted for use with a vacuum pump for preventing back-flow upstream in the event of vacuum pump failure, said valve assembly comprising:
- housing means defining a fluid flow passageway therethrough;
- valve means carried by said housing means and movable between an open position permitting the flow of fluid through said flow passageway and a closed position blocking said flow passageway, said valve means including a sealing element for sealing said fluid flow passageway and a plunger attached to said sealing element;
- said housing defining a chamber slidably receiving said plunger;
- an ambient air passageway in said housing adapted at one end for communication with the ambient atmosphere and communicating at the other end with said chamber for applying pressure to said plunger portion to assist in moving said valve means to the closed position;
- and
- an ambient air control valve carried by said housing and having a fluid pressure access port for communication with high pressure fluid from the pump, said valve being movable by fluid pressure from the pump to close said ambient air passageway and movable upon the release of fluid pressure in the event of pump failure to allow ambient air into said chamber to force said valve means quickly into said close position, said plunger and said sealing element being attached by a ball and socket joint to provide a more reliable sealing contact between said sealing element and said passageway, and means for retarding the escape of ambient air from said chamber upon restarting of said pump to delay opening of said valve means.
A back-flow prevention valve assembly adapted for use with a vacuum pump for preventing back-flow upstream of the pump in the event of pump failure, said valve assembly comprising:
- housing means defining a fluid flow passageway, including an inlet orifice, therethrough;
- valve means carried by said housing means and comprising a sealing member and a driving member attached together by a ball and socket joint, said sealing member being movable between positions opening and closing said fluid flow passageway;
- said housing defining a chamber slidably receiving said driving member;
- an ambient air passageway in said housing adapted at one end for communicating with the ambient atmosphere and communicating at the other end with said chamber for applying pressure to said driving portion to move said sealing member to a said closed position;
- and
- a normally open diaphragm control valve carried by said housing and having a fluid pressure access port for communication with high pressure fluid from the pump, said diaphragm valve being movable by fluid pressure from the pump to close said ambient air passageway, and movable to a normally open position upon the release of fluid pressure to allow ambient air into said chamber to force said sealing member quickly into said closed position,
- and wherein, said driving member has a selected clearance from the walls of said chamber sufficiently small to restrict the passage of ambient air therebetween so as to delay movement of said sealing member to said open position upon restarting of vacuum pump after an interruption.
A back-flow prevention valve assembly adapted for use with a pump for controlling the direction of flow of the fluid being pumped, said valve assembly comprising:
- housing means defining a fluid flow passageway therethrough;
- valve means carried by said housing means and movable between an open position permitting the flow of fluid through said flow passageway and a close position blocking said flow passageway;
- said housing defining a chamber and said valve means including driving means associated with said chamber for moving said valve means;
- an actuating fluid passageway in said housing adapted at one end of communication with a fluid source having a higher pressure than the fluid being pumped and communicating at the other end with said chamber for applying pressure to said driving means to move said valve means to the closed position;
- an actuating fluid control valve having a fluid pressure access port for communication with high pressure fluid from the pump, said valve being movable by fluid pressure from the pump to close said actuating fluid passageway and movable upon the release of fluid pressure in the event of pump failure to allow actuating fluid into said chamber to force said valve means into said closed position;
- and
- restriction means for restricting the passage of actuating fluid from said chamber to delay movement of said valve means to the open position upon restarting of the pump.
Dependencies are inferred from the claim text.