Mechatronic flow sensor works to the principle of spring-supported piston. The piston is located in the valve seat in the housing. The piston is lifted by the flowing medium against the spring resistance during which piston position is detected by binary way via an inductive sensor or in an analogue way via a sensor with GMR cell. Flow ranges at 25 l/min, 50 l/min, 75 l/min and pressure ranges up to 200 bar. With decreasing flow, the piston is reliably reset to its initial position through spring resistance. Setting screw enables to individually set and fix the switch points and can also be can be (pre)set continuously. The fast, mechatronic flow sensor works on binary or analogue signal output with a response time of ? 10 ms. The robust mechanical design makes it maintenance free and supports application in high pressures and harsh environments.