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 capable of being driven by a flow of the extinguishing agent, the motor having:
• an inlet for supplying the extinguishing agent to the motor;
• an outlet for discharging the extinguishing agent from the motor;
• and
• an output shaft capable of being driven by the motor;
• an admixing pump for conveying the extinguishing agent additive, the admixing pump having:
• an input shaft coupled to the output shaft of the motor;
• a fluid input for providing the extinguishing agent additive;
• and
• at least two fluid outputs for discharging the extinguishing agent additive conveyed by the admixing pump,
• wherein the admixing pump is a piston pump, which has a plurality of cylinders, and
• wherein each of the at least two fluid outputs is fluidly connected to at least one cylinder and each cylinder is fluidly connected to exactly one fluid output;
• an extinguishing agent additive inlet line having a first inlet-side end and a second pump-side end,
• wherein the second pump-side end is fluidly connected to the fluid input of the admixing pump;
• 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 outlet 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 at least two fluid outputs of the admixing pump and the second admixing line-side end is fluidly connected to the admixing line at an admixture point;
• and
• a return flow line having a first pump fluid output-side end and a second pump fluid input-side end,
• wherein at least one first return-flow-capable fluid output of the at least two fluid outputs of the admixing pump can be switched via a switching device to either be fluidly connected to the first pump fluid output-side end of the return flow line or to the first pump-side end of the extinguishing agent additive outlet line,
• wherein other fluid outputs of the at least two fluid outputs of the admixing pump that are not capable of return flow are fluidly connected to the first pump-side end of the extinguishing agent additive outlet line, and
• wherein the second pump fluid input-side end of the return flow line is fluidly connected to the extinguishing agent additive inlet line or to the fluid input of the admixing pump.