If there is a need in a pump installation to change the operating point, this can be achieved, among other things, by means of control by throttling. This easy to implement control allows affecting the flow rate of the installation by modifying the installation resistance. For this purpose, the flow rate can be adjusted on the pressure side of the pump by means of a throttling device so that the head provided by the pump lies above the required one. This reduces the capacity and the installation characteristic becomes steeper. As a result, the operating energy input of the pump also increases.
However, the control by throttling under the aspect of efficiency is energetically meaningful only for certain pump types since the pump is no longer operating in the optimal operating point and with low efficiency. In addition, maintenance of the control by throttling can be very cost-intensive, particularly for processes with corrosive fluids.