A valve assembly comprising: a sealing housing, which sealing housing includes a lower housing portion and an upper housing portion, the upper housing comprising a main body that is adapted to encircle a portion of a pipe, an upper surface, and an integral valve housing section disposed generally therebetween, the integral valve housing section having a slot therein; a valve comprising an upper valve surface and a lower valve surface, the valve being movable in the slot in the integral valve housing section between an open position and a closed position, the slot comprising an upper slot surface and a lower slot surface; and a plurality of biasing members movably positioned within the integral valve housing section and configured to urge the valve toward one of the upper slot surface and the lower slot surface, wherein the valve is configured to be movable axially along a longitudinal axis of the pipe, and the valve is a flat plate member, and wherein each of the plurality of biasing members resides within a threaded bore that extends through the outer surface of the upper housing portion and into the slot, wherein the biasing member and the respective threaded bore are at least partially offset from the valve, in order for a biasing force to act on the upper or lower slot surfaces (88a, 88b) of the valve, wherein each biasing member includes an elongate, cylindrical shank separating a tip from a distal end, and is a threaded cylinder movably residing within the threaded bore, wherein the plurality of biasing members are disposed on one same side of the pipe, characterized in that the plurality of biasing members comprise four biasing members including a first biasing member positioned at a first corner of the valve, the second biasing member positioned at a second corner of the valve, a third biasing member positioned along a first edge of the valve, and a fourth biasing member positioned along a second edge of the valve. a sealing housing, which sealing housing includes a lower housing portion and an upper housing portion, the upper housing comprising a main body that is adapted to encircle a portion of a pipe, an upper surface, and an integral valve housing section disposed generally therebetween, the integral valve housing section having a slot therein; a valve comprising an upper valve surface and a lower valve surface, the valve being movable in the slot in the integral valve housing section between an open position and a closed position, the slot comprising an upper slot surface and a lower slot surface; and a plurality of biasing members movably positioned within the integral valve housing section and configured to urge the valve toward one of the upper slot surface and the lower slot surface, wherein the valve is configured to be movable axially along a longitudinal axis of the pipe, and the valve is a flat plate member, and wherein each of the plurality of biasing members resides within a threaded bore that extends through the outer surface of the upper housing portion and into the slot, wherein the biasing member and the respective threaded bore are at least partially offset from the valve, in order for a biasing force to act on the upper or lower slot surfaces (88a, 88b) of the valve, wherein each biasing member includes an elongate, cylindrical shank separating a tip from a distal end, and is a threaded cylinder movably residing within the threaded bore, wherein the plurality of biasing members are disposed on one same side of the pipe, characterized in that the plurality of biasing members comprise four biasing members including a first biasing member positioned at a first corner of the valve, the second biasing member positioned at a second corner of the valve, a third biasing member positioned along a first edge of the valve, and a fourth biasing member positioned along a second edge of the valve.