The Diaphragm pump reference article from the English Wikipedia on 24-Jul-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Diaphragm pump

A diaphragm pump uses a combination of the reciprocating action of a rubber diaphragm and suitable non-return valves to pump a fluid.

There are two main types of diaphragm pump:

• In the first type the diaphragm is sealed with one side in the fluid to be pumped and the other in air. The diaphragm is moved up and down, causing the volume of the pump chamber to increase and decrease. A pair of non-return valves prevent reverse flow of the fluid.
• The second type of diaphragm pump has one or more unsealed diaphragms with the fluid to be pumped on both sides. The diaphragm(s) again are moved up and down, the fluid flows round the edge of the diaphragm in the suction cyclewhich seals in the delivery cycle. The operation of the diaphragms is similar to the valves in an internal combustion engine.

Applications

Diaphragm pumps are low lift, low head pumps with low flow rates. They can handle sludges and slurrys with a moderate amount of grit and solid content. Excessive solids cause blockages.