Device that sets the delivery flow of a variable pump to zero on reaching a set pressure such that this pressure is maintained in the system (Figure D 71). This means that all internal and external pressure losses are covered by this device.
As during this process the pump operates against the related system pressure, the resulting losses must not be underestimated. Here the losses in the pump often make up the major part of the losses (e.g. on vane pumps up to 15 % of the nominal power).
If the pressure controller is operated by a continuously adjustable valve (generally a proportional valve), to reduce the power losses as a consequence of internal leakage the response pressure can be pre-selected on a case-by-case basis (see Pressure-flow (p-Q) control of a pump).
Figure D 71: Performance map for a pressure-controlled pump