What Is Viscosity? Why Is It Important?

June 12, 2021

Viscosity of often referred to as the thickness of a fluid. You can think of water (low viscosity) and honey (high viscosity). However, this definition can be confusing when we are looking at fluids with different densities.

At a molecular level, viscosity is a result the interaction between the different molecules in a fluid.This can be also understood as friction between the molecules in the fluid. Just like in the case of friction between moving solids, viscosity will determine the energy required to make a fluid flow.


How Fluid Viscosity Affects Pump Selection:

One of the most important aspect to understand before any pump selection is the viscosity of the fluid which is going to be pumped.

Fluid viscosity or thickness will affect how it will behave in a pump. However, this is where things start becoming complicated because the viscosity of fluids/liquids can change under different conditions.

What Is Thee Most Important About Viscosity During Pump Selection?

Viscosity is essentially resistance to flow and this has implications for pumps. If you have a high-viscosity, sticky fluid on your hands, it clings and it’s much harder to remove than a low-viscosity fluid.

It is the same in a pump, where you use impellers instead of your hands, to move the fluid. If you are pumping fluids like motor oil that stick to the surface of the impeller, this is a problem that needs to be considered.

Viscosity Visual Identification

We understand at times there are liquids that are foreign to your experience and their technical data may not always be apparent, so we have prepared this visual representation of viscosity to better aid you in identifying at least a ballpark centipoise value of your liquid.

100 Centipoise (cp)
500 Centipoise (cp)
1000 Centipoise (cp)
5000 Centipoise (cp)
10,000 Centipoise (cp)

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