"Micro Pre Temp" Glass Tube Rotameters are ideal for bypassing the metering applications in case of liquid and gas, wherein the operating environment is with the limitations of glass metering tube. The product works on the principle of 'variable area'. There is a tapered borosilicate glass, wherein the float is allowed free movement in upward and downward direction. However, the direction of fluid flow is from bottom to top. In this Glass Tube Rotameter, the float stops at a position wherein the weight of float and buoyancy forces are perfectly balanced in ratio to the flow rate. Hence, the instantaneous flow rate is measured with the vertical position of float visible on the scale.