The KOBOLD flow meter model DRB is used for measuring and monitoring liquids. The device works according the well-known blade wheel principle. The four vane blade wheel is retained radially in a highquality sapphire bearing. The sensor is supplied ready-to-install with pipe fittings or with weld-on sleeves. The blade wheel is set in motion by the flowing medium. Magnets are embedded hermetically sealed in the ends of the blade wheels. The magnets generate electrical pulses in a Hall-effect sensor mounted outside the flow area. Various electronics units can be used to display and monitor the volumetric flow.