Fluids with low viscosity typically offer low resistance. They shear easily, their molecules move quickly, and they're generally straightforward to pump and process.
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High-viscosity fluids, on the other hand, behave quite differently. They flow slowly, resist deformation, and, in some cases, act more like solids than liquids, posing challenges when it comes to pumping.
That said, pumping high-viscosity fluids is entirely possible with the right setup. It often comes down to choosing the proper pump assembly and, in some cases, giving the fluid a bit of extra assistance.
This article outlines key guidelines and tips for effectively handling high-viscosity fluids, from selecting the appropriate pump at the start to incorporating specialized pump heads designed for the task.
Pumping High-Viscosity Fluids
While it is possible to pump high-viscosity fluids, it can be difficult to do this properly. A common limitation is the pump technology being utilized, particularly in terms of its flow rate.
For example, it would be especially challenging to achieve a flow rate of 1000 milliliters per minute with high-viscosity fluids, because high-viscosity fluids tend not to move easily.
In order for a pump to process fluid, the fluid must be able to move through the tubing to the pump. The choice of pump will make a significant difference in these cases.
Guidelines for Pumping High-Viscosity Fluids
There are a number of considerations when selecting a pump to process high-viscosity fluids.
- Larger Tubing Size: If you're trying to pump high-viscosity fluids through tubing that's too small, you're not going to have very much success. In fact, the path to the pump will likely become restricted.
- Temperature: Heating the fluid, particularly on the inlet side, will cause a reduction in fluid viscosity, helping it to move more easily through the tubing to the pump head.
- Pressure Feed: The application of pressure on the inlet side can help to force feed fluid through the tubing and to pump head.
- Low RPM: Reducing the RPM will improve the fluid’s movement through the system. It is advisable to aim for an RPM at or below around 400 because this will reduce stress on the pump and the motor, ensuring adequate fluid movement.
Many of Fluid Metering’s pumps feature a special pump head intended specifically for the processing of high-viscosity fluids. This pump head features a cylinder casing with options to keep the fluid warm within the pump head. This is important because heating the fluid can improve its smooth movement throughout the assembly, making it easier to pump high-viscosity fluids.
Common Pitfalls
Now that the key "do's" have been covered, it's important to consider some common mistakes to avoid when pumping high-viscosity fluids.
As expected, many of these “don’ts” are the reverse of best practices. They include using pumps with tubing that's too small, operating at high RPMs, and neglecting to incorporate pressure feed or heating. These missteps can place unnecessary strain on the pump and often result in poor performance or system failure.
Fluid Metering Pumps and High Viscosity Fluids
Pumps are highly application-specific, so it’s often best to consult an expert when selecting a pump for a particular need—such as processing high-viscosity fluids.
Fluid Metering offers a broad selection of pumps designed for a wide range of applications. Backed by years of industry experience, the company’s team works closely with customers to help identify the most suitable, high-quality pump solutions—consistently delivering performance that meets or exceeds application requirements.
Acknowledgments
Produced from materials originally authored by Patrick DeRuvo from Fluid Metering, Inc.
About Fluid Metering, Inc.
Fluid Metering, Inc. (FMI) is a worldwide leader in life science pumps and dispensers, having pioneered the first valve-less piston pump over 64 years ago. With specialized expertise in fluidics and applications, Fluid Metering, Inc. supports instrument developers in tackling complex fluidic challenges.
Committed to innovation through collaboration, Fluid Metering, Inc. advances health, sustainability, and quality of life. ISO 9001:2015 certified.
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