초록 ▼

A back flow preventer valve assembly for protecting fluid supply systems against back flow of contaminating fluids includes a pair of serially connected check valves positioned within respective housings which are connected together and to inlet and outlet fittings by slidable sleeve-type couplings.

A back flow preventer valve assembly for protecting fluid supply systems against back flow of contaminating fluids includes a pair of serially connected check valves positioned within respective housings which are connected together and to inlet and outlet fittings by slidable sleeve-type couplings. The couplings are sealed to the fittings and to the valve housings by resilient annular gaskets, preferably O-rings. Tie bolts extend longitudinally from the inlet fitting coupling to the outlet fitting coupling to retain the assembly together. This assembly provides for interchangeability of components, easy removal of the valve units from the line in which they are connected without disconnection of the inlet and outlet fittings, and for easy replacement or substitution of a fitting. Each check valve includes a poppet assembly of advantageous modular construction, with components easily replaceable. In one form of the invention, a venting valve is connected between the two valve housings to relieve any pressurized fluid which might leak back through the downstream check valve when inlet fluid pressure is below the threshold pressure of the first check valve. The venting valve includes a cylindrical resilient diaphragm-type valve closure member which shuts off the venting valve whenever inlet line pressure is above the threshold pressure of the first check valve. The venting valve serves to provide, in addition to the tandem check valves, a third safety feature preventing infiltration of back flow into the inlet line.

대표청구항 ▼

A back flow preventer valve assembly, comprising: a first valve unit including an inlet end, an outlet end and a check valve operable to open and admit flow toward the outlet end when a predetermined pressure differential exists between the outlet end and the inlet end, each end of the unit having a

A back flow preventer valve assembly, comprising: a first valve unit including an inlet end, an outlet end and a check valve operable to open and admit flow toward the outlet end when a predetermined pressure differential exists between the outlet end and the inlet end, each end of the unit having an external cylindrical connecting surface; a second valve unit substantially identical and interchangeable in the assembly with the first valve unit; a sleeve connecting the outlet end of the first valve unit to the inlet end of the second valve unit, said sleeve having internal cylindrical surfaCes at its ends circumjacent the external cylindrical connecting surfaces of the valve units, with resilient gaskets engaged between the sleeve and each valve unit and including means for seating the gaskets; an inlet fitting positioned adjacent to the inlet end of the first valve unit, said inlet fitting having a cylindrical downstream end portion shaped and sized similarly to said external cylindrical connecting surfaces, and including means for connection to a fluid supply line; an inlet end coupling connecting the inlet fitting to the inlet end of the first valve unit, said coupling having an internal cylindrical surface circumjacent the external surfaces of the inlet fitting and the inlet end of the first valve unit, with stop means at the upstream end of the coupling for limiting movement at the inlet fitting away from the valve unit, and means at the downstream end of the coupling abutting longitudinally against a surface of the first valve unit, with resilient gaskets engaged between the end coupling and each of the inlet fitting and the first valve and including means associated with the coupling, the fitting and the first valve unit for seating the gaskets, an outlet fitting positioned adjacent to the outlet end of the second valve unit having an external cylindrical surface similar to that of the inlet fitting, and including means for connection to a fluid delivery line; an outlet end coupling similar to and reversed in orientation from the inlet end coupling, and connected similarly with gaskets interposed between the outlet end coupling and each of the outlet fitting and the downstream end of the second valve unit; removable longitudinal fastening means extending between the inlet end coupling and the outlet end coupling and urging the couplings toward one another to tightly retain the valve assembly together; whereby the valve units may be removed without disconnection of the inlet and outlet fittings from the supply and delivery lines, by removing the fastening means and sliding the couplings longitudinally outwardly.