Variable Flow Meter

Variable area flow meters are simple and versatile devices that operate at a relatively constant pressure drop and measure the flow of liquids, gases, and steam. The position of their float, piston or vane is changed as the increasing flow rate opens a larger flow area to pass the flowing fluid. The position of the float, piston or vane provides a direct visual indication of flow rate. Design variations include the rotameter (a float in a tapered tube), orifice/rotameter combination (bypass rotameter), open-channel variable gate, tapered plug, and vane or piston designs.