Acrylic Body Rotameter

NRG GLOBAL Glass Tube Variable Area Flow Meters (Rotameters) are intended for general in line and ByPass metering applications (i.e. for Gas & Liquid) where operating conditions are with the limitations

of Glass metering tubes. These are the principle of Variable Area.

The float moves freely up and down tapered borosilicate glass with fluid flow from bottom to top. The

float takes up a position where buoyancy forces and the float weight are balanced in proportion to flow

rate. The Vertical position of the float as indicated by scale is the measure of the instantaneous flow

rate.

2. Principal of Operation

When fluid or gas flows through a taper tube containing a float, a pressure difference of P1 and P2 is

created between upper and lower side of the float. The float moves upwards by a force obtained by

multiplying the pressure differential by the maximum cross-sectional area ofthe float.

Due to taper tube, as the float moves upwards, the fluid passing area increases as a result of which the

differential pressure decreases. Upward movement of float stops when the dead load is dynamically

balanced by the differential pressure.

Tapering of metering tube is so designed that the vertical movement of the float becomes linearly

proportional to the rate of flow and the scale is provided to read the position of the float, thus giving

birth to flow rate indication