KF series gear pumps are external gear pumps that operate according to the positive displacement principle. Here, the fluid is transported from the suction to the discharge end by rotation of the two gear shafts in the tooth gaps along the housing wall.
The geometric displacement volume Vg is displaced per wheel revolution. A value that is stated in technical documentation as the nominal volume Vgn to identify the pump size.
Gear pumps are in principle self-priming - extremely high viscosities may require upstream pressure. The displacement cycle described initially takes place without exhibiting appreciable pressure build-up. Only after external loads have been specified, e.g. by delivery head, pressure drops, pipe elements, etc., is the working pressure required to overcome these resistances established.