Diaphragm

In mechanics, a diaphragm is a sheet of a semi-flexible material anchored at its periphery and most often round in shape. It serves either as a barrier between two chambers, moving slightly up into one chamber or down into the other depending on differences in pressure, or as a device that vibrates when certain frequencies are applied to it.

A diaphragm pump uses a diaphragm to pump a fluid. A typical design is to have air on one side constantly vary in pressure, with fluid on the other side. The increase and decrease in volume caused by the action of the diaphragm alternately forces fluid out the chamber and draws more fluid in from its source. The action of the diaphragm is very similar to the action of a plunger with the exception that a diaphragm responds to changes in pressure rather than the mechanical force of the shaft.

Pressure regulators for fuel systems in automotive applications use diaphragms as part of their design. This includes fuel-pressure regulators in petrol fuel injection systems and the pressure-reducing converters in most vehicles fueled with liquefied petroleum gas and compressed natural gas.

See also

wikipedia:Diaphragm (mechanical device)