In processing, reliable equipment makes all the difference between smooth operations and costly downtime. Among the unsung heroes of processing plants are positive displacement pumps—workhorses that keep products moving efficiently through production lines.
Whether you're transferring chocolate, paint, creams, or other products, choosing the right pump technology impacts everything from product quality to your maintenance budget. In this blog post, you'll learn how positive displacement pumps can support your processing operations and why choosing the right pump design matters.
At its core, a positive displacement pump works by trapping a fixed amount of fluid and forcing it from the intake side to the discharge side of the pump. Unlike dynamic pumps that depend on velocity to move fluids, positive displacement pumps physically push the product through the pump, creating flow that's directly proportional to the pump's rotor speed.
This working principle makes positive displacement pumps particularly effective when consistent, precise flow is required, regardless of fluctuations in discharge pressure. As the pump's internal components (lobes, gears, or vanes) rotate, they create expanding cavities on the suction side, drawing fluid into the pump. These cavities then seal and transport the fluid to the discharge side, where the cavity collapses, forcing the fluid out of the pump.
At Unibloc® Hygienic Technologies (UHT), we define positive displacement pumps as lobe pumps, gear pumps, and vane pumps. We need to note that some industry professionals include many other types of pumps in their definitions.
Unlike reciprocal pumps, the rotary motion of lobe and gear pumps offers a pulse-free precise flow. Gear pumps, in particular, when operated at low speed, offer volumetric control suitable for filling and metering operations.
The mechanical simplicity of their design, combined with the ability to handle fluids of varying viscosities, makes positive displacement pumps indispensable to diverse processing applications from food production to pharmaceuticals.
The fundamental distinction between these pump types lies in how they move fluids. Centrifugal pumps rely on rotational energy from an impeller to create velocity, which then converts to pressure energy as the fluid exits the pump. By contrast, positive displacement pumps capture and move discrete volumes of fluid through the system.
This difference creates several important operational contrasts:
While the term "negative displacement pump" isn't common industry terminology, it helps conceptualize how different pump technologies function. A positive displacement pump physically pushes fluid through the system by creating sealed cavities that transport fixed volumes of product.
Negative displacement pumps use centrifugal action to force the liquid through the pump. When fluid exits the pump, the movement makes room for more fluid to follow… negative displacement. Typically, these pumps are less efficient, but because of their low cost and simple, low-maintenance design, they are widely used in pumping applications involving low viscosity liquids.
A key advantage of positive displacement pumps is their ability to handle shear-sensitive products without compromising quality. In many processing applications—particularly with food and personal care products—maintaining product texture and appearance is non-negotiable.
When products like ground meat or cosmetic creams are subjected to the high speeds and centrifugal forces of conventional pumps, they can experience "smear" or texture degradation that consumers find unappealing. Lobe, gear, and vane pumps operate at lower speeds with gentle product handling, preserving the intended consistency and appearance of products.
One of the most surprising benefits of these pumps is their versatility. A well-designed lobe pump can handle viscosities ranging from 1 to 1,000,000 centipoise—meaning the same pump could transfer thin liquids or substances as thick as peanut butter. This versatility enables processors to accommodate multiple product types without investing in separate pumping stations.
For processing professionals, understanding the differences between lobe and gear pumps is essential for optimal operations:
What many processing engineers don't realize is the extent to which maintenance issues drain operational efficiency. When pumps require daily cleaning—as they often do in viscous applications—the process traditionally consumes significant time and labor.
Standard hygienic pumps often have numerous parts and require tools for disassembly. This complexity not only extends downtime but also increases the risk of improper reassembly, particularly during third-shift operations when staffing skilled technicians is a challenge.
Our experts have observed that up to 90% of pump damage incidents occur during cleaning processes—not during normal operation. This damage leads to unplanned downtime and costly repairs.
Modern pump designs are changing the maintenance equation. UHT has developed innovations that allow technicians to take apart, clean, and reassemble a lobe pump in 20 minutes or fewer—compared to two hours for traditional pump designs.
Our QuickStrip® lobe and gear pumps have features that contribute to faster maintenance cycles:
By selecting the right positive displacement pump for your application, processors can achieve significant improvements in operational efficiency, product quality, and maintenance costs—making their processing facility more competitive. Contact our application experts for selection advice.