How to Avoid Shear Damage Through Pump Selection

The Most Important Selection Rule: Process Step Changes the Right Answer

One of the biggest mistakes in pump selection is assuming the same pump should be used everywhere in the process. In real plants, the right pump often changes depending on where you are in the line.

For example, a higher-volume step may call for one technology, while final blending, packaging, or gentle recirculation may call for another because product handling becomes more important than raw throughput.

When AODD Pumps Are a Good Low-Shear Choice

AODD pumps are a common answer for shear-sensitive service because they do not rely on tight clearances or fast-moving rotating elements that can work the fluid aggressively. That makes them a strong fit when the product needs gentler transfer and the process benefits from simple maintenance, self-priming, or flexible operation.

PSG® highlights this directly in multiple markets. Wilden® notes that its AODD pumps are a strong option for minimizing shear damage in brewing and wine, chemical transfer and paints and coatings because they do not have the tight clearances or high-speed pumping elements that often create excess shear in other pump types.

In practice, AODD pumps are often favored at the end of the process - during final transfer, packaging, drum filling, or gentle recirculation - where preserving product condition matters as much as moving volume.

For a broader overview of why AODD pumps are often used in these applications, see the AODD technology page and Wilden's® AODD product overview.

When Another Pump Technology May Be Better

Low shear does not automatically mean "always use an AODD pump." The right answer still depends on flow and the process step. There are applications where another pump is a better low-shear choice.

For example, in higher-volume paints and coatings duty, a gear pump may be selected because it can deliver the required flow while still minimizing shear better than a centrifugal pump in that part of the process. In other shear-sensitive applications, vane pumps or progressive cavity pumps may be the better fit depending on how the fluid responds to speed and slip.

The key point is that shear-sensitive service is not one technology - it is a selection strategy built around protecting the product.

Why Centrifugal Pumps Can Be the Wrong Choice for Sensitive Fluids

Centrifugal pumps are widely used and can be the right answer in many services, but they are not always the best choice for shear-sensitive fluids. That is because they move fluid by adding velocity and then converting that velocity into pressure, which can work the fluid harder than gentler positive-displacement technologies.

That does not make centrifugal pumps "bad." It just means they are often better suited for water-like utilities, flushing, cleaning, or process steps where the product is not especially shear-sensitive.

In some paint and pigment-heavy processes, centrifugal pumps still make sense for flushing lines or for abrasive utility service. But if the real problem is preserving the product itself, they are often not the first place to start.

Mouvex® as a Low-Shear Option for Sensitive, Higher-Value Fluids

If the application demands especially gentle, consistent flow, eccentric disc technology can become a strong option. Mouvex® seal-less eccentric disc pumps are designed around low-shear, pulse-free transfer and are often considered when product quality and recovery are major priorities.

PSG® describes Mouvex® eccentric disc pumps as providing extremely gentle, pulse-free flow for shear-sensitive products on the Mouvex® overview page, the eccentric disc pump technology page and product pages such as C-Series.

This kind of technology often enters the conversation when the fluid is air-sensitive, premium, or expensive enough that reducing pulsation, slip, and product disturbance is worth the additional investment.

Flow Rate Still Matters (Do Not Protect the Product but Miss the Output)

A pump that protects the fluid but cannot meet the required flow is still the wrong pump. That is why the best shear-damage strategy always balances gentle handling with the actual throughput requirement.

This is where many real-world selections split by process step. Lower-flow finishing or packaging may favor a gentler diaphragm pump, while a larger-volume transfer step may require a different technology that still keeps shear as low as the process allows.

Speed Is Often as Important as Pump Type

Avoiding shear is not only about choosing the right technology. It is also about how hard you run it. Even a pump that is generally considered shear-friendly can damage the product if it is operated too fast for the fluid.

That is why low-shear applications are often designed around controlled speed, larger pump sizes run more slowly, and piping layouts that do not force the product through unnecessary restrictions.

If the product becomes unstable only at higher speed, that is often a clue that the technology may still be acceptable - but the operating point is not.

Simple Application Examples Where Shear Drives the Choice

A few common examples make the selection logic easier to explain:

• Paints and coatings: the product can be shear-sensitive, so the wrong pump can degrade finish quality or destabilize the formulation.

• Wine and beverages: gentler handling helps reduce excess aeration, which can affect taste, smell, and appearance.

• Adhesives and sealants: excessive shear can change how the material applies or performs downstream.

• Food and personal care products: texture, consistency, and appearance can all suffer if the fluid is worked too aggressively.

A Simple Selection Checklist for Avoiding Shear Damage

Before approving a pump, use this checklist:

• Confirm whether the fluid is shear-sensitive in practice, not just in theory.

• Define where the pump sits in the process (bulk transfer, blending, finishing, packaging, cleaning, etc.).

• Match the technology to both product sensitivity and required flow rate.

• Avoid assuming the highest-flow pump is the best pump if it damages the product.

• Review whether operating speed can be reduced to protect the fluid.

• Check for piping restrictions that may add extra stress even if the pump itself is gentle.

• If product quality is critical, choose the operating point and technology that preserve the product first, then scale around that.

The Simplest Rule of Thumb

If the fluid changes when you move it, the pump is part of the product-quality equation. That means the correct selection is not just about moving the liquid - it is about moving the liquid without changing what makes it useful.

The best low-shear pump is the one that meets the duty while leaving the product as close as possible to the way it started.

Next Steps: Narrow the Options Faster

If you need help narrowing down which pump technology is most likely to protect a shear-sensitive fluid, start with the Pump Finder or contact the PSG® Store team to review the application in more detail.

You can also browse AODD pump options by brand: Shop Wilden® and Shop All-Flo™.