3
Device description
3.1
Functional principle
BT / BTH series pumps are external gear pumps that work according to the
positive displacement principle.
S = Suction connection
P = Pressure connection
When rotated, two gearwheels meshing together produce a volume enlarge-
ment as a result of the opening of the tooth spaces on the suction side (S),
so that medium can flow in and so that a corresponding volume is displaced
simultaneously by immersion of the teeth into the filled tooth spaces on the
pressure side (P). Fluid transport takes place through entrainment in the tooth
gaps along the wall of the wheel chamber. The so-called geometric flow rate
V
g
is being displaced per wheel rotation.
The actually delivered amount of liquid does not correspond with the theo-
retical value, it is being reduced through losses due to the necessary toler-
ances. The losses are less the lower the operating pressure and the higher
the viscosity of the medium.
Gear pumps are self-priming within wide limits. The displacement cycle de-
scribe initially takes place without exhibiting appreciable pressure build-up.
Only after setting external loads, for example, through delivery heights, flow
resistances, line elements, etc. will the required working pressure arise to
overcome these resistances.
As usual with non-axial play compensated pumps, the lateral clearance be-
tween gear and front face has been set in such a way that the maximum
allowable operating pressure is managed in an adequate and secure way.
Bearing and shaft seal of the device are lubricated by the media. The device's
operating life will be reduced if the medium contains abrasive ingredients.
Gear pump BT / BTH
10
2021-02-05 88026290002-04
