Patent attributes
Redundant valve apparatus including a first valve seat and a second valve seat located in the fluid passage of a hollow valve body between the inlet portion of the fluid passage and the outlet portion of the fluid passage and a poppet member having valve seat sealing surfaces for cooperating with and sealing the first valve seat and the second valve seat. One of the valve seats is fixed within the hollow valve body and the other valve seat is movable within the hollow valve body. The redundant valve apparatus also includes an actuator nut for controlling the operation of the poppet member and for moving the movable valve seat to cause the valve seat sealing surfaces on the poppet member to sequentially engage one valve seat and then the other valve seat. The redundant valve apparatus includes a spring for biasing the poppet member to the proper position within the hollow valve body such that the first valve seat and the second valve seat are properly positioned with respect to the valve seat sealing surfaces of the poppet member in all valve open and closed conditions. An expandable and contractible bellows surrounds the first valve seat and the second valve seat and the associated poppet member and the spring for providing a fluid tight seal in case either the first valve seat or the second valve seat and the associated valve seat sealing surfaces should leak. The bellows also permits the redundant valve apparatus to be leak tested when it is installed in position to be used.
