Measuring the flow of low viscosity fluids is ideally suited to small turbine flow meters, such as Titan’s 800, 900 or 1000 series.
Using the Pelton Wheel, the turbine flow meter operates well with low viscosities, has a low differential, instantaneous pressure loss and has characteristics that will not change significantly with small changes in the properties of the liquid. The low-end performance of a small turbine meter actually improves as the viscosity drops so the Reynolds number increases keeping the device working in a turbulent area at lower fluid velocities.
On the other hand, positive displacement flowmeters, such as Titan’s Oval Gear flow meters, operate effectively with higher viscosity liquids. The accuracy of the oval gear flowmeter depends on the liquid’s viscosity and the higher the viscosity, the better the range and accuracy.
The reason behind this is to do with fluid slippage between the gears and pipe walls. As the viscosity of the liquid increases, the fluid slippage quickly drops and a higher accuracy of measurement is achieved.
Other parameters will also affect the choice of flow meter in an application and Titan’s technical article explains the factors that determine flow meter performance in more detail.