Difficulties When Pumping High Viscosity Fluids

by | May 4, 2023

Pumping high-viscosity fluids poses unique challenges across various industries, from oil and gas to food processing. Understanding the properties of these fluids and selecting the appropriate high viscosity pump is crucial for efficient operations. In this article, we’ll delve into the science behind high-viscosity fluids, explore the types of pumps suitable for high viscosity pump project applications, and discuss operational challenges, maintenance best practices, and future technological advancements in the field.

You can deal with pumping high-viscosity fluids only if you have the right solution. Though it may seem difficult to deal with the unique challenges of pumping high-viscosity fluids, it is possible to do so with the right pump types. High-viscosity liquids and viscous materials in general exhibit unique behavior under stress and require high viscosity pump solutions that are built with them in mind. This behavior poses unique difficulties when they are pumped. The right high-viscosity fluid pump lies at the heart of the solution.

What is Fluid Viscosity?

Fluid viscosity—the property of a fluid to resist the force causing it to flow—is an important property of fluid dynamics for managing viscous fluids. In simple terms, viscosity is both a measurement of how quickly a liquid flows, and refers to a fluid’s resistance to flow. High-viscosity fluids, like honey, tomato paste or molasses, are typically thick and resistant to movement, whereas low-viscosity fluids flow easily, like water. The viscosity of a liquid is determined by factors such as temperature, pressure, and composition. Generally, fluids with a viscosity above 100 centipoise (cP) are considered high viscosity.

Trying to pump a fluid much thicker than water is challenging for many traditional fluid pumps such as centrifugal pumps. Most of them fail to deal with the dynamic viscosity challenges that these thick and difficult-to-pour fluids pose. However, you can move such fluids with consistency with well-designed high-viscosity fluids pumps. 

Types of Viscosity Found in Fluids

Fluid viscosity can be classified into two main categories: Newtonian liquids and Non-Newtonian liquids. 

The viscosity of fluids can be classified into two main categories: Newtonian liquids and Non-Newtonian liquids. 

Newtonian Liquids, such as water or alcohol, exhibit constant viscosity regardless of shear rate or agitation. These fluids have a linear relationship between viscosity and shear stress. Such fluids can be managed with a centrifugal pump.

Non-Newtonian Liquids are of two types : 

  • Thixotropic or shear thinning liquids that exhibit reduced viscosity when agitated or mixed, such as paint. 
  • Dilatant or shear thickening liquids that exhibit increased viscosity when agitated or mixed, such as quicksand. 

The Science Behind High Viscosity Pumps

Pumping high-viscosity fluids requires specially engineered equipment due to these materials’ resistance to flow. The pump’s manufacture must overcome the fluid’s internal friction and provide sufficient force to move it through the system. The science behind this kind of pump involves understanding how different pump designs generate the necessary pressure to transport viscous fluids and materials effectively.

Types of High Viscosity Pumps

Several types of pumps are commonly used for handling high-viscosity fluids:

Gear Pumps: This kind of centrifugal pump uses intermeshing gears to trap and transfer fluid from the inlet to the outlet. They are suitable for viscous fluids but may struggle with abrasive particles.

Progressive Cavity Pumps: These pumps use a helical rotor inside a stator to create a progressing cavity that moves fluid through the system. They are highly efficient for handling high-viscosity and shear-sensitive fluids.

Peristaltic Pumps: These pumps use rollers or shoes to compress a flexible tube, creating a vacuum that draws fluid through the tube. They are suitable for applications where contamination must be minimized, such as the food or pharmaceutical industries.

The Challenges that High-Viscosity Fluid Pumps Face

The changing nature of viscosity requires dynamic changes in the performance of the high-viscosity fluid pump in real time. 

For dealing with a range of high-viscosity fluids, centrifugal pumps are not well suited (even medium viscosity pumps like Barrel or Drum pumps are a poor choice). They cannot deal with the close tolerances needed and the unique needs of non-newtonian liquids. They generally fail with the load changes on the pump with viscosity variation. There is a need for dynamic variation and optimization of flow and the head of the pump. 

As the viscosity increases, the pump performance typically needs to be optimized to match the variation in viscosity. If optimization remains incomplete or incorrect, the pump may fail. For an effective pump design, you also need the right kind of impeller for high-viscosity fluids without the risk of failure. 

How to Determine the Right Pump for High Viscosity?

Selecting the right pump for pumping high-viscosity requires considering viscosity, temperature, pressure, and flow rate requirements. Progressive cavity pumps are often preferred for their ability to handle viscous fluids effectively while minimizing shear and degradation.

It is important for you to first measure the viscosity of the fluid well that is to be transferred prior to purchasing a pump. This can be done using a device called a viscometer for fluids, which shows a single flow condition like that of Newtonian fluids. 

For liquids with viscosities that can vary depending on flow like in non-Newtonian fluids, an instrument called a rheometer is used. 

Viscosity values are measured in centipoise (cp), centistokes (cSt), and Saybolt Second Universal (SSU). The greater the value, the more viscosity challenges that need to be addressed.

Typical liquid Centipoise
Water 1 1 31
Milk 3 4 40
No. 4 fuel oil 12.6 15.7 80
Cream 20 20.6 100
Vegetable oil 40 43.2 200
SAE 10 oil 88 110 500
Tomato juice 180 220 1,000
SAE 30 oil 352 440 2,000
Glycerine 800 1,100 5,000
Honey 1,500 2,200 10,000
Glue 3,000 4,500 20,000
Mayonnaise 5,000 6,250 28,000
Molasses B 8,640 10,800 50,000
Sour cream 15,000 19,000 86,000

Viscosity values also determine the design, selection, and sizing of piping, valves, and other aspects of the pumping system. The viscosity values of the fluid to be pumped from a container determine the selection of the pump for the high-viscosity fluid. The type of application and the operating requirements also play an important part in pump selection for highly viscous fluids. 

The pump remains the key driver in the movement of the viscous fluid. All other elements must match its features and functionalities.

Choosing the Correct Pipeline Size

The pipeline must be wider than the inlet of the pump and the maximum size of solids to be handled with reasonable allowances for non-clog performance. 

Operational Challenges and Solutions

One of the primary challenges when pumping high-viscosity fluids is maintaining consistent flow rates and preventing pump cavitation. To address this, pumps may require variable-speed drives or heating systems to reduce viscosity. Additionally, ensuring proper pipe sizing and minimizing bends and restrictions in the system can help optimize flow.

Maintenance of High Viscosity Pumps

Maintenance tips for high-viscosity pumps are crucial to ensure reliable operation and prevent downtime. Here are some essential practices:

Regular Inspection: Perform routine inspections of pump components such as seals, bearings, and couplings to identify wear or damage that may affect performance.

Lubrication: Proper lubrication of moving parts is essential to reduce friction and extend the lifespan of pump components. Follow manufacturer recommendations for lubrication intervals and types of lubricants.

Cleaning: Clean the pump and surrounding area to prevent contamination and ensure optimal performance. Remove any debris or buildup that may impede flow or damage components.

Temperature Control: Monitor and control the temperature of the pumped fluid to prevent overheating or crystallization, which can lead to pump failure.

Safety best practices for high-viscosity pumps include:

Proper Ventilation: Ensure adequate ventilation in pump rooms to prevent the accumulation of vapors or fumes that pose health risks.

Guarding: Install guards and safety shields to protect operators from moving parts and potential hazards.

Lockout/Tagout Procedures: Implement lockout/tagout procedures to safely shut down and isolate pumps during maintenance or repair work to prevent accidental startup.

Personal Protective Equipment (PPE): Provide workers with appropriate PPE, such as gloves, eye protection, and protective clothing, to minimize the risk of injury while handling high-viscosity fluids and operating pumps.

Future Outlook and Technological Advancements

The future of high viscosity pumping will likely see continued pump design, materials, and technology advancements. Manufacturers are developing pumps with improved efficiency, reliability, and ease of maintenance. Integrating IoT sensors and predictive analytics will also enable proactive maintenance and optimize real-time performance. As industries continue to innovate, high-viscosity pumps will play a vital role in meeting the demands of challenging fluid-handling applications.

Why Choose EDDY Pumps?

EDDY Pump Corporation manufactures state-of-the-art high-viscosity fluid pumps. The EDDY Pump Corporation offers a full line of products that are specifically designed for high viscous fluids. The mission statement states it well: “We pump solids, not water.” 

If you have the challenge of pumping slurry, high solids, extremely viscous material, paste, high abrasives (sand & gravel), and material filled with solids, then look no further. 

The EDDY Pump Corporation is a globally renowned premier industrial pump manufacturer founded in 1984. To know more about us, please follow this link

More Information on Slurry Pumps

EDDY Pump industrial slurry pumps are non-clog pumps designed for high solids industrial pumping applications. Our patented pump technology outperforms all centrifugal, vortex, and positive displacement pumps in a variety of the most difficult pumping applications.


Cross Section of Horizontal Slurry Pump

Cross Section of Horizontal Slurry Pump

Cross Section of Horizontal Slurry Pump

Vertical Slurry Pump

The traditional pumps get clogged, wear down, fail quickly, and require a lot of maintenance.

EDDY Pumps are non-clog and have the following features:

  • Open Rotor Design
  • Non-Clog operation
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The EDDY Pump’s geometric rotor acts as a mixer for even highly viscous non-newtonian quality liquids. It addresses fluids with even less than 5% free liquid. This is an impossible task for traditional centrifugal pumps.

To view our range of slurry pumps or pumps for high-viscosity fluids, please follow this link: EDDY Slurry Pumps.

Solving your problem of dealing with highly viscous fluids

If you are facing the challenge of pumping a high-viscosity liquid, you need to find the best pump for high-viscosity fluids out there. A specially designed pump for highly viscous fluids should be the one that you go with. 

To read more such articles, please visit our blog

For your Slurry pump, dredging equipment application in construction, mining, chemical, oil & gas, pulp and paper, sewage treatment and marine industries, email EDDY Pump or call us at 619-558-3250. You can also Request a free sales quote.


FAQ 1: What are high-viscosity fluids?

Fluids that are very difficult to pour are high-viscosity fluids. They move sluggishly and are difficult to deform. 

FAQ 2: What are the applications of high-viscosity fluids?

Lubricants for heavy machinery or as brake oil in automobiles are highly viscous fluids. Liquid foods, animal fats, and edible cooking oils are some examples of such fluids. 

FAQ 3: What are the challenges associated with handling high-viscosity fluids?

They require a specific tubing design and a pressure feed to make it flow. They also need to be pumped at a lower RPM to move the fluid. 

FAQ 4: What are the methods for measuring the viscosity of high-viscosity fluids?

Shear Viscosity is of two types-shear, kinematic. It is measured by viscometers, rheometers, non-contact rheology, and formulation techniques. 

FAQ 5: What are some common high-viscosity fluids?

Common high-viscosity liquids are crude oil and some derivatives. Other examples are paraffin, honey, asphalt, methanol, resin, crude benzene, etc.

Order or Get Selection Help

Let our sales or engineering support help in your slurry pump and dredge equipment selection. Call (619) 258-7020

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