R.R. Flowmeters Pvt. Ltd manufactures Rotameters. R.R. Flowmeters Pvt. Ltd offered Rotameters consist of a tapered tube containing a float. Fluid passes through the meter exerts an upward force on the float that is counterbalanced by the force of gravity. In the Rotameters, the point at which the float stays constant indicates the volumetric flow rate, which is often read on a scale on the meter tube. These tubes are made of metal, glass, or plastic.