Admixing system for fire extinguishing systems and method for operating such an admixing system

An admixing system for fire extinguishing systems for producing an extinguishing agent/extinguishing agent additive mixture (premix) by admixing an extinguishing agent additive to an extinguishing agent comprising:

• a motor able to be driven by a flow of the extinguishing agent which has an inlet for supplying the extinguishing agent to the motor and an outlet for discharging the extinguishing agent from the motor, and an output shaft able to be driven by the motor;
• an admixing pump for conveying the extinguishing agent additive which has an input shaft coupled to the output shaft of the motor, an input for providing the extinguishing agent additive and an output for discharging the extinguishing agent additive;
• an admixing line having a first motor-side end and a second outlet-side end, wherein the first motor-side end is fluidly connected to the outlet of the motor;
• an extinguishing agent additive line having a first pump-side end and a second admixing line-side end, wherein the first pump-side end is fluidly connected to the output of the admixing pump and the second admixing line-side end is fluidly connected to the admixing line at an admixture point, which is different from the first motor-side end of the admixing line;
• a branching line with a first admixing line-side end and a second outlet-side end, wherein the first admixing line-side end is fluidly connected to the admixing line at a branching point located between the first motor-side end of the admixing line and the admixture point;
• a branching valve arranged in the branching line;
• a motor rotational speed measuring device;
• and
• a controller designed to fully or partially open and/or close the branching valve on the basis of a rotational speed of the motor measured by the motor rotational speed measuring device.