There 3 plungers for piston pump of F+W proportioner, which can inject 3 plungers volume into the proportioner outlet at the same time, and can also make 1 or 2 of the plunger displacement return, such as a 3% piston pump, when 2 plungers return, it can achieve 1% mixing ratio, and when 1 plunger pump returns, it is 2% mixing ratio. Suitable for mobile fire extinguishing system.

For vehicle mounted applications, the three-way valve can be equipped with a pneumatic or electric actuator for easy remote operation.