The BGK all-metal, low-volume variable-area flow meter, also known as a rotameter, is designed for flow measurement of suitable liquids or gases. It provides an indication of the current flow rate in volume or mass per unit of time. This rotameter consists of a conical stainless steel measuring tube and a vertically movable float. The media flows from bottom to top through the metering tube of the flow meter. The float is lifted until an annular gap between the measuring cone and the float is produced, which corresponds to the flow. The height of the float resulting from the flow rate is transmitted by the permanent magnet in the float through the magnetic tracking system, rotating the pointer axis of the analog indicator unit.