Square pumps have a constant performance with a linear increase in volume flow. This means that the torque of the pump increases in proportion to the square of the speed. These pumps are particularly suitable for applications in which the load changes with the third power of the speed. One example of this is the pumping of liquids with a constant pressure difference.


– Simple control and monitoring

– Low costs, e.g. for the drive

– Better efficiency at constant flow rate and pressure

Pumps with a constant load torque have a constant output with a linear increase in pressure. These pumps are well suited for applications in which the load changes linearly with the speed, for example when pumping liquids with a variable pressure difference.

The affinity law states that the energy consumption of a pump changes in proportion to the third power of the speed. This means that a 20% reduction in speed can lead to an 80% reduction in energy consumption, provided that the pump load varies quadratically with the speed and that the efficiency of the pump remains constant. This principle can be used to reduce the energy consumption of pumps and thus minimize costs and environmental impact.

The VLT® HVAC Drive FC 102 from Danfoss distributes the operating hours evenly across all pumps thanks to the pump cascade controller. This reduces wear on individual pumps and significantly increases their service life and reliability.