A fluid control valve comprising: a cover portion with a first inner surface; a body portion with a second inner surface, the body portion including an elongated seat member substantially aligned along a plane perpendicular to a flow axis of the fluid control valve, the first and second inner surfaces defining a chamber when the cover portion and the body portion are joined, the chamber including an inlet and an outlet in communication with the chamber; and a diaphragm disposed between the cover portion and the body portion, the diaphragm including a flexible member disposed in the chamber and having a first position in which the flexible member is inverted to define a passageway to permit communication between the inlet and the outlet and a second position to prevent fluid communication between the inlet and the outlet, wherein in the second position the diaphragm dissects the chamber into a diaphragm sub-chamber, an inlet sub-chamber in communication with the inlet and an outlet sub-chamber in communication with the outlet, and the diaphragm includes a reinforced fabric embedded in a rubber matrix; characterized in that the diaphragm exclusively biases the flexible member from the first position to the second position such that when pressure is equalized between the inlet and outlet sub-chambers (24a, 24b) and the diaphragm sub-chamber, the tension within the diaphragm urges the diaphragm to the second position and a tension force is concentrated in the reinforced fabric when the flexible member is in the first position so that the flexible member conforms to and seals against the elongated seat member when the flexible member is in the second position, and wherein additional diaphragm structures or biasing devices are not used to urge the flexible member from the first position to the second position. a cover portion with a first inner surface; a body portion with a second inner surface, the body portion including an elongated seat member substantially aligned along a plane perpendicular to a flow axis of the fluid control valve, the first and second inner surfaces defining a chamber when the cover portion and the body portion are joined, the chamber including an inlet and an outlet in communication with the chamber; and a diaphragm disposed between the cover portion and the body portion, the diaphragm including a flexible member disposed in the chamber and having a first position in which the flexible member is inverted to define a passageway to permit communication between the inlet and the outlet and a second position to prevent fluid communication between the inlet and the outlet, wherein in the second position the diaphragm dissects the chamber into a diaphragm sub-chamber, an inlet sub-chamber in communication with the inlet and an outlet sub-chamber in communication with the outlet, and the diaphragm includes a reinforced fabric embedded in a rubber matrix; characterized in that the diaphragm exclusively biases the flexible member from the first position to the second position such that when pressure is equalized between the inlet and outlet sub-chambers (24a, 24b) and the diaphragm sub-chamber, the tension within the diaphragm urges the diaphragm to the second position and a tension force is concentrated in the reinforced fabric when the flexible member is in the first position so that the flexible member conforms to and seals against the elongated seat member when the flexible member is in the second position, and wherein additional diaphragm structures or biasing devices are not used to urge the flexible member from the first position to the second position.