Rotating vane flow meters series DRG are used for measuring and monitoring low viscous liquids. Series DRG flow meters are working according the well-known rotating vane principle. A magnet fitted in the vane and hermetically sealed from the medium transfers non-con-tacting the rotary motion to a Hall-effect sensor mounted in the housing. The sensor converts the rotary motion which is proportional to the flow to a frequency signal. A series-con-nected electronics unit converts the signal to an analogue output, limit contacts or display.