The DW-K has been developed e.g. for the monitoring of coolant recirculation systems with low flow rates. Compact and ideal for switching points between 0.1 and 2.5 l/min. In accordance with the wishes and requirements of our customers. The principle: A special piston, fitted with permanent magnets, is held in a defined position by a spring. Depending on the rate of flow, the medium slides the piston against the strength of the spring. If the flow exceeds or falls short of the present switch point, the reed switch outside the medium is activated without contact via the permanent magnet. The construction is absolutely leakproof, and can easily be disassembled for any cleaning that needs to be done. The special piston that is divided into a measuring and guiding section combines precise switching with high reliability. Furthermore, this flow switch is insensitive to contamination and calcification.