By Matthew Doughty

This article will form a comparison between the traditional piston plunger dosing pump and the mechanical diaphragm metering pump. The two are similar size and price range but ultimately they are two different animals.

The piston plunger pump's major advantage are the high pressures that it can dose at. Piston plunger pumps can easily achieve a pressure of 2,000 psi or greater, where the mechanical diaphragm pumps rarely exceed 200psi.

The piston pump is also very easy to strip and rebuild, and is incredibly durable. The only parts which require regular replacements are the piston seals, which are relatively inexpensive and easy to fit.

The piston pump's downside is that the process fluid lubricates the piston seal, which causes a slight leakage of whatever fluid is being dosed. This is usually not an issue, but dependent on the fluid, could be potentially hazardous in some environments.

The mechanical diaphragm pump, on the other hand, is completely self-contained, so unless the diaphragm fails, no liquid will escape the system.

Mechanical diaphragm pumps are readily available and are easy to service, unlike their more traditional hydraulic counterparts. They are slightly more expensive than a piston pump, though it is usually not noticeable.

The main con of a mechanical diaphragm pump is that diaphragms wear and eventually fail, which means that they need to be replaced fairly regularly to maintain operation.

This information is provided by Doseuro (UK) Limited, and is correct to the best of our knowledge, however, we do not place any guarantee on its accuracy and accept no responsibility for anything that goes wrong because of usage of it.

Matthew Doughty is an administrator at Doseuro (UK) Limited and has experience in the field of chemical dosing.