Abstract: The longevity and safety of pressure-responsive, flexible diaphragms is improved by providing laminated construction of sealing and reinforcing layers that "breathe" through a portion of their cross sections. In one embodiment the flexible diaphragm comprises a laminate having a layer of perforated fabric-like reinforcing material on the low pressure side and a layer of impermeable elastomeric sealing material on the high pressure side with or without an additional layer of said fabric, with or without perforations on the high pressure side and with the areas of bond between the reinforcing material and sealing material being substantially continuous. In another embodiment the laminate comprises an inner layer of perforated fabric-like material bonded to outer layers of perforated elastomeric material on the low pressure side. The elastomeric sealing material layer on the high pressure side of this latter embodiment may be perforated.