Pumps – What Do They Mean When They Say…

If you’re unfamiliar with the world of fluid pumping, whether it’s for drinking water supply, rainwater harvesting or wastewater treatment, you may be puzzled by the terms and phrases used in the industry. But a basic understanding will help you to choose the right pump for your needs, so let’s just explain a few of them.

In this series of weekly blog posts, we have looked at the four ranges of DAB pumps and explained each pump’s features, with links to a glossary where you can find more commonly-used technical terms simply explained.

As we end this short series, we’d like to share with you a few other terms you’ll probably encounter in the pumping industry.

Other Common Pump Terms

You may also hear the expression ‘head’ in connection with pumps. In pumping terms, this refers to the pressure exerted by the depth of water above the pump inlet. While static head is purely the pressure of gravity created by a column of water, dynamic head is the total pressure of water in a system. Dynamic head calculations take into account vertical rise – the difference in height between the surface of the water source and the water discharge point – and friction loss, which is the pressure needed to overcome loss of force while the water travels through pipework. Maximum head lift refers to the difference in height between the water source to the point of outflow, and head loss is the drop in pressure between these two points. Accurate calculation of head loss is essential to ensure there is sufficient pressure for the pump to operate efficiently. Maximum immersion depth is the deepest point below the surface of water that a pump can operate. Water hammer is the result of a pressure surge or high-pressure shockwave created when water is forced to change direction or stop abruptly. Water hammering prematurely wears parts and in extreme cases can cause damage or injury if system components fracture or are blown off under pressure.

If the pump chamber contains insufficient water it won’t be able to prime properly. This will cause a condition called dry running that creates air locks and places strain on the motor and eventually, electrical or mechanical failure. To prevent dry running, a standard priming cycle starts the pump and cuts out if priming doesn’t occur and must be restarted manually.

To refer back to the four previous posts in this series, please click on the following links: