The Impact of Viscosity on Pump Performance

If you’re a pump owner, you would understand that transporting thicker liquids is quite a different experience. Viscosity represents the resistance that a liquid offers to the flow. It doesn’t only take longer to displace but also impacts your pump’s performance. 

VEMC is one of the leading Kirloskar pump distributors based in Mumbai, and in this blog, we explain how viscosity affects your pump performance.

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As your water pump dealer may explain, viscosity has an effect on some of the most critical pumping parameters. Let’s see how.

  1. Flow rate: To put it simply, with an increase in viscosity, there is a decrease in the flow rate of a pump. However, a number of other factors such as physical properties, geometry of the tubing, temperature and the distance of liquid from the pump may also play a moderating role.
  2. Head: Viscosity has an extraordinary and negative effect on pump performance. With an increase in viscosity, there is a dramatic drop in the head.
  3. Efficiency: While pumps may still be able to displace highly viscous liquids, they will inevitably hit a point of diminishing returns due to a drop in efficiency. This means you may require a more powerful pump which will consume more energy to move a more viscous liquid.

Which pump is suitable to move your liquid type?

When selecting a pump on the basis of fluid properties, there is no one-size-fits-all. Now that it is clear that higher viscosity affects a pump’s performance negatively, let’s take a closer look at which pumps are best suited for moving your viscous liquids.

While centrifugal pumps are good enough for low viscosity liquids like water, their performance and efficiency may reduce significantly for more viscous liquids. These pumps may draw more power when transporting thicker liquids causing wastage of energy and piling up of electricity bills. For such liquids, the best pumps are positive displacement pumps such as diaphragm pumps, hose pumps, vane pumps and gear pumps. These can operate at lower speeds and at variable flow rates, delivering a constant flow of the fluid at desired speed. 

Viscosity is an important factor to consider when selecting the right pump, and also the size of instrumentation, piping, valves and filters. Appropriate selection of these items is necessary to account for friction loss due to viscosity. 

For more information on which pump is best to displace the liquid at your home or business facility, speak to our experts on 022 43436655 or email us at We at VEMC are the leading Kirloskar pump distributors based in Mumbai with a rich industry experience of over 70 years.