Diaphragm vacuum pumps (also called membrane pumps) are oscillating positive displacement pumps. The diaphragms generate vacuum by expanding the volume in the vacuum chamber which in turn reduces the pressure in the vacuum chamber thus causing atmospheric pressure air to be pushed into the chamber. The air in this chamber is then pushed out from the vacuum chamber through a different route (gas outlet) with the use of valves. These periodic movements of the diaphragm generate vacuum at the inlet of the pump.