Variable area flowmeters, commonly referred as Rotameters are most popular flow measuring instruments for liquids and gases.The movement of float in a taper tube creates variable area which allows passage of fluid through it.When the float is balanced, its corresponding position indicates fluid flow rate passing through it.The Rotameters are mainly available in Glass and Metallic tube construction. The Glass Tube Rotameters are normally used for transparent, low temperature and pressure fluids, while Metal tube rotameters are preferred for opaque, high temperature pressure fluid flow measurement applications.