How diaphragm valves with metal valve bodies work There are two general designs of diaphragm valves: The full bore type and the weir type. The animation shows how a medium flows through and is shut off by a weir type metal diaphragm valve. Valves based on the diaphragm principle are recognized as having a design with minimal deadleg. This is partly due to the fact that the actuator and body are hermetically separated from each other by the diaphragm, which means that all mechanical parts are located outside the media wetted space.