KWFS Series Liquid Flow Switch OEM IP65 Liquid Flow Switches Sensor For Heating, Air Conditioning The KWFS series liquid flow paddle switch, suited for pipes of industrial plants: heating and air conditioning, refrigeration systems and heat pumps. Flow control of water and normal media. The KWFS series liquid flow paddle switch offers an economical flow proving solution. The paddles are adjustable to fit 1 to 8" size pipe. Features Adjustable range and differential settings.