Rotameter

the rotameter is a simplest form of fluid measuring instrument. It consist of a borosilicate tapered glass tube placed vertically with its smaller diameter at the bottom. The float used in the tube is made up of heavier non-corrosive substance which resists the vertical flow of the fluid passing through the annular space between the tube and the head of float. The fluid passing through the orifice, balances the weight of the float in the metered fluid and in equilibrium position, indicates the flow rate of the fluid against a calibrated external scale fitted by the side of the tube.