DXP Pacific Industrial Pumps

How Fluid Viscosity Affects Your Pump System

There are many different types of fluids being pumped throughout the world every single day. From clean water to thick slurries and everything in between, every type of liquid will flow through its respective pump system differently. Fluid viscosity is one of the most important factors to consider when selecting pumps and configuring a system for optimized performance.

Fluid Resistance and Temperature

Low-viscosity fluids like water or most beverages will generally move through a pump system rather easily with low resistance. High-viscosity fluids like syrups and many oils move slower, with the fluid maintaining more consistent integrity. Temperature can also affect fluid viscosity, as higher heat tends to lower the viscosity of pumped fluids.

Pump Selection Based on Fluid Viscosity

When it comes to pump selection, fluid viscosity is one of several key factors along with other application-specific criteria for your operation’s ideal pump system. Pump selection is typically not as difficult when dealing with low-viscosity fluids. Centrifugal pumps are often a standard choice for these less-challenging processing applications.

Centrifugal Pumps vs. Positive Displacement Pumps

As viscosity thickens, there will usually be an increased amount of power drawn to move the fluid through the pump system. High-viscosity liquids can dramatically affect centrifugal pump performance, energy efficiency, and flow rates. Positive displacement pumps are commonly used for more viscous fluid applications. There are a number of different types of positive displacement pumps suited for various fluids, viscosities, and specialty applications. Examples include vane pumps, hose pumps, diaphragm pumps, gear pumps, and screw pumps. 

Positive displacement pumps are able to operate at lower speeds and offer variable flow rates, which is great for fluids with thicker viscosities. The optimized performance can be achieved by keeping higher-viscosity fluids running through the pump system at consistent temperatures. This maintains consistent viscosity. If variables like temperature cause the fluid to increase or decrease in viscosity, you could start to experience performance issues.

Peristaltic pumps are another popular pump option, especially in applications with variances in viscosity. They can effectively handle fluids with both low and high viscosities and can run dry without the risk of major pump failure.

Pump Configuration and Operation

In addition to pump selection, fluid viscosity can also help determine pump system configuration and operating practices. It is very important to make sure there are no restrictions on the suction side. Having a flooded suction is crucial. You will also want to consider making the pipework size larger throughout the system. This will decrease friction and prevent drag loss.

Selecting the right pump equipment and configuring your system will require careful planning. You can research known viscosities of most common fluids, which are normally listed in units of SSU (Saybolt Seconds Universal) or CST (centistokes). Pump manufacturers and distributors can provide product specs relating to a pump’s viscosity capabilities. Choosing a pump designed to handle the specific viscosity range of your process fluid(s) can make a significant difference.

For help with pump selection and custom configuration based on your specific pumping application and process fluids or materials, contact DXP Pacific today. Let our team help you make the right pump decisions and get the most out of your pump system.