Low Reynolds Number Impellers

A Reynolds number is a ratio that refers to a mixer’s capacity for laminar and turbulent flow — at low Reynolds numbers, fluids move in a smooth, sheet-like motion. At higher numbers, growing differences between fluid speed and direction create eddy currents, which can lead to cavitation.

Knowing the Reynolds number of a given mixer when using different fluids helps to anticipate the transition from laminar to turbulent flow. This knowledge, in turn, lets engineers design more effective mixing systems by choosing an impeller with a geometry, diameter, rotational speed and other characteristics that will produce the desired mixing effect.

Philadelphia Mixing Solutions Limited manufactures low Reynolds number impellers for use with our Raven, Unifirst and other drives. We’d be happy to put together a package of equipment that offers a complete turnkey solution for your project. Learn more below, or contact our office for assistance.


High-viscosity fluids typically require a low Reynolds number impeller suitable for non-Newtonian mixing and other shear-thinning applications. Philadelphia Mixing Solutions has supplied products for paint and coating, adhesive and personal care product manufacturing, among other processes. Failing to use the proper impeller for these and other applications can lead to longer batch times, uneven incorporation of added ingredients and dead zones where impellers cannot agitate properly due to higher-than-anticipated viscosity.

The CounterFlow Impeller Platform

The CounterFlow system is a Philadelphia Mixing Solutions exclusive product. A low Reynolds number impeller, it’s suitable for non-Newtonian mixing and other shear-thinning applications. When used to blend liquids that evolve over time — including those used in food processing and polymerisation — a CounterFlow impeller will provide minimal blend times and excellent product homogeneity.

The CounterFlow is a versatile impeller capable of providing a wide range of mixing solutions. In the right environment, as part of a well-engineered system, it will deliver reliable performance at a low cost of ownership.

Anchor Impellers

Philadelphia Mixing Solutions also offers anchor-type impellers for low Reynolds number applications. An excellent option for high-viscosity fluid mixing, our products provide effective blending and heat transfer in fluids in excess of 50,000 cP. Anchor impellers provide agitation near the floor of a vessel, making them highly useful in squat batches.

We offer the option of equipping our high-viscosity mixing impellers with a wall scraper system for better heat transfer.

Contact Philadelphia Mixing Solutions to Learn More

In addition to product sales, we also offer comprehensive diagnosis, modelling and consulting services. We can work with you to analyse your processes and anticipate your mixing needs. If your application calls for a low Reynolds number impeller, we can recommend the right item or customise a product to your specifications.

We maintain the largest mixing-focused lab in the world as well as a team of 36 engineers and other fluid dynamics experts. Let us help you develop an efficient, cost-effective in-tank mixing process — contact our office today, or follow the links on this page for more information about our high-viscosity, low Reynolds number fluid mixing impellers.