A fluid control valve comprising: a cover portion with a first inner surface and a first channel, the first channel including a first radial outer wall and a first radial inner wall shorter in length than the first radial outer wall; a body portion secured to the cover portion, the body portion having a second inner surface and a second channel, the second channel including a second radial outer wall and a second radial inner wall shorter in length than the second radial outer wall, the first and second inner surfaces defining a chamber, the first channel and the second channel circumscribing the chamber, a gap formed to provide a passage from a cavity, which is defined by the first radial outer wall, the first radial inner wall, the second radial outer wall, and the second radial inner wall, to the chamber; and a diaphragm disposed between the cover portion and the body portion, the diaphragm including a flexible member disposed in the chamber, a lip member circumscribing the flexible member and a tab, an upper surface of the flexible member including a substantially smooth wall portion having a constant radius of curvature which extends part way and circumscribes a central portion, wherein a thickness of the central portion increases in a radial direction from the substantially smooth wall portion to the centre of flexible member such that the upper surface is substantially flat along the central portion, wherein the first channel and the second channel define the cavity that circumscribes the chamber and each channel (36,37) receives a portion of the lip member and pinches the lip member to seal the fluid control valve and hold the diaphragm. a cover portion with a first inner surface and a first channel, the first channel including a first radial outer wall and a first radial inner wall shorter in length than the first radial outer wall; a body portion secured to the cover portion, the body portion having a second inner surface and a second channel, the second channel including a second radial outer wall and a second radial inner wall shorter in length than the second radial outer wall, the first and second inner surfaces defining a chamber, the first channel and the second channel circumscribing the chamber, a gap formed to provide a passage from a cavity, which is defined by the first radial outer wall, the first radial inner wall, the second radial outer wall, and the second radial inner wall, to the chamber; and a diaphragm disposed between the cover portion and the body portion, the diaphragm including a flexible member disposed in the chamber, a lip member circumscribing the flexible member and a tab, an upper surface of the flexible member including a substantially smooth wall portion having a constant radius of curvature which extends part way and circumscribes a central portion, wherein a thickness of the central portion increases in a radial direction from the substantially smooth wall portion to the centre of flexible member such that the upper surface is substantially flat along the central portion, wherein the first channel and the second channel define the cavity that circumscribes the chamber and each channel (36,37) receives a portion of the lip member and pinches the lip member to seal the fluid control valve and hold the diaphragm.