Which Type of Pump is Commonly Used for Handling Viscous Fluids?

Handling viscous fluids—from shampoo and syrup to cosmetics —presents unique challenges in industrial applications. Unlike water-like fluids that flow easily, viscous materials have a high flow resistance, which causes substantial energy losses, heat generation, and potential damage to both product and equipment. The solution is to use a different pumping method—positive displacement pumps. Gear pumps, piston pump, and lobe pumps are the most common and reliable options for handling thick materials. This article explains why these pumps work well and helps you decide which one is right for your application. Extremely thick, non-flowable products—such as body scrubs or silicone—are better handled with ZONESUN’s filling machine with hydraulic discharge machine. These materials fall outside the scope of this article.

Why Are Viscous Fluids So Challenging to Pump?

Highly viscous materials have strong internail resistance and extremely poor flowability, these makes them prone to blockage and difficult to transport, and requires greater force and more specialized positive displacement pumps.

High internal friction (high viscosity)

High viscosity means the pump is hard to push and slow down flow inside pipe. It requires much more force to make it flow.

Poor self-flowing ability (low gravity flow)

Materials like honey, toothpaste, or cosmetic cream hardly move under their own weight. So hopper ourlet of filling machine and tank bottoms are easily getting clogged and this needs pressure or mechanical force to move the products.(Pressurized hopper or  with mixer)

Easy to create dead zones and residue

Thick materials don’t spread out by themselves. They tend to cling to pipe walls, elbows, and valves. This causes blockages and unstable filling speed.

Many viscous materials are shear-sensitive

Some pastes change texture or get damaged if handled with too much force. So this requires filling machine has enough pushing power without altering the product.

How Do Positive Displacement Pumps Solve These Challenges?

The working principle of moving fluid for postive displacement pumps is "grabbing a fixes amouth and pushing it forward". This makes them suit high-viscosity material. The three commonly used pump type are gear pumps, lobe pump(also called rotor pump), and piston pump, each suited for different application range

Gear Pumps: It use two intermeshing gears to move fluid. Simple  structure and lower cost makes it suitable for medium-viscosity, homogeneous liquids like lubricating oil.However, the meshing gears generate some shear force, so they are not suitable for fluids containing particles, which may be damaged or stuck.

In the food industry, gear pumps can be used for particle-free, uniform liquids like honey as an economical option.

Lobe (Rotor) Pumps: It uses two non-contacting rotating lobes to move fluid gently, minimizing damage to particles or product structure.

They are easy to clean and has wider filling range, meeting high hygiene standards required in food, cosmetic, and pharmaceutical applications.

The number of lobes can be customized according to the material, allowing compatibility with a wide range of viscosities, soft particle-containing, or shear-sensitive products. Their versatility exceeds that of gear pumps.

Piston Pumps: The reciprocating motion of the piston provides powerful force and precise filling, thus enabling the conveying of materials.—ideal for very thick pastes like cosmetic cream.

However, regular maintenance requires operator add grease to the cylinder, which can raise hygiene concerns for food customers.

As a result, piston pumps are less recommended in food applications

How Should You Select the Right Pump for Your Application?

Choosing a pump depends on a few key factors:

Material Feature: Viscosity, shear sensitivity, abrasiveness, and whether it contains solids are important when choose the right pump.

Process requirements: Determine the needed flow rate, pressure, filling accuracy,  and hygiene standards.

Operational priorities: Evaluate production cost, maintenance needs, working labor, working speed and ease of cleaning.

What Support Systems Are Needed for Reliable Operation?

Even the best pump requires proper support:

Heating and Insulation: Keeping fluids warm reduces viscosity and improves flow like petroleum jelly.

Pipe Design: Use short, wide pipes with minimal bends to reduce resistance.

Pressurized hopper or  with mixer:  Ensures consistent feed of high-viscosity or thick materials into the pump, preventing air pockets and uneven flow.

Conclusion

For handling pumpable viscous fluids, positive displacement pumps—specifically gear pump, piston pump and rotary lobe types—are the standard and reliable solutions. Each of them has excellent performance within a specific application. By accurately assessing the challenges and requirements of your application, ZONESUN can offer reliable packaging solution and help you turn a challenging process into a smooth operation.