System Duty Point | impeller.net

Pump Selection

Posted on December 14, 2020February 2, 2021 by bs

It is highly recommended to always select the smaller pump if the specified system duty point is between two possible pump curves. The resulting capacity reduction has, in heating systems, no appreciable effect on the effective heating performance. The positive effects are lower noise levels, lower investment costs and improved economy. For heating installations it is customary to undersize pump capacities up to 10% below the specified duty. To avoid Cavitation (vapour formation within the pump) it is necessary to maintain at the pump suction port an adequately high positive pressure (static head) in relation to the vapour pressure of the fluid being handled. The minimum required inlet heads for Glandless pumps are generally listed in pressure charts. Glanded pumps require calculations in accordance with the NPSH information.

Total Head

Posted on December 8, 2020January 28, 2021 by bs

Defined as the effective mechanical force exerted by the pump onto the pumped fluid and expressed as unit of weight at the local gravitational constant. It is, at constant speed and constant flow, independent of the density of the fluid, but dependent on its viscosity.