An aseptic or sanitary diaphragm valve has a valve body and at least one cylinder-actuated valve mechanism. A chamber is defined between a cylinder head and a plate or disk, which has a central bore or passage. A flexible diaphragm extends across the cylinder below the plate or disk. A piston within a cylinder is connected with a valve member foot portion, with a stem passing from the foot portion, penetrating the diaphragm, and passing through the bor or passage to the piston. A compression spring urges the piston to either its raised or lowered position, and air pressure may be used to lower or to raise the piston and the associated valve foot. An aperture in the cylinder can reveal a compromise of the diaphragms.