Many industries rely on pumps for their daily operations, including the dairy, brewing, food processing, beverage manufacturing, and personal care industries. Highland Equipment supplies various hygienic pumps for a wide range of applications. In this blog, we’ll take a detailed look at positive displacement, centrifugal, and high-pressure pumps, including their suitability for certain processing applications.

What Is a Positive Displacement Pump?

A positive displacement pump works by repeatedly taking a specific amount of fluid and mechanically moving it through the system. It uses cyclic pumping action driven by pistons, gears, rollers, screws, diaphragms, or vanes.

Positive displacement pump types include reciprocating and rotary pumps. The reciprocating pump relies on repeated back-and-forth strokes of a plunger or piston. These repeatable pumps are suitable for accurate dosing or metering applications.

Rotary positive displacement pumps use rotating gears to move fluids. The gears form a liquid seal with a pump casing, creating suction through the pump inlet.

What Is a Centrifugal Pump?

Centrifugal pumps use rotational energy from a motor to transfer fluid through a system. When the fluid passes through the pump, the rotating impeller adds velocity and pressure to the fluid as it is pushed toward a diffuser.

What Is a High-Pressure Pump?

High-pressure pumps have a conveying height of up to 1,200 meters. These pumps are common in high-rise buildings, which require sufficient pressure to supply the entire structure.

How Do These Pumps Compare?

Using a controlled amount of force, positive displacement and centrifugal pumps both transfer a set quantity of fluid from an inlet to an outlet. However, their mechanisms are different. Centrifugal pumps transfer kinetic energy from a motor to the liquid using an impeller, which rotates to pump fluid at a high velocity out of its discharge point. Positive displacement pumps displace fluid out of a cavity through suction.

These are some other ways in which centrifugal, positive displacement differ:

  • Performance: A centrifugal pump can vary the flow rate by changing its pressure. The flow rate is constant in a positive displacement pump, even during pressure changes.
  • Fluid viscosity: When dealing with highly viscous fluids, a centrifugal pump sees a decrease in flow rate due to frictional losses inside the pump’s cavity. A positive displacement pump’s internal clearance allows for viscous fluid handling and can increase flow rate as the viscosity increases.
  • Efficiency: A centrifugal pump’s efficiency peaks at a specific pressure, while the efficiency of a positive displacement pump varies according to the pressure.
  • Suction lift: Centrifugal pumps cannot create a suction lift, while a positive displacement pump creates a vacuum on its inlet to create a suction lift.
  • Shearing: The high-speed motor in a centrifugal pump can shear certain media. A positive displacement pump creates low shear, making it suitable for shear-sensitive fluids.

Which Pump Is Suitable for Your Sanitary Process?

The ideal pump for your sanitary process depends on the specific factors of your application. Centrifugal pumps are best for high-flow, low-viscosity applications, where you can take advantage of their high-volume capabilities. You can also customize them to move more gallons per minute than other types of pumps.

Positive displacement pumps generally run better in high-viscosity, low-flow applications. They allow you to control flow rate more flexibly, operate at lower speeds, and can prime themselves during “dry” periods where there is no liquid in the pump. Plus, positive displacement pumps can process suspended solids.

Consider the following specifications of your project to determine the best choice:

  • Desired flow rate
  • Pressure capability
  • Fluid characteristics, such as corrosiveness, temperature, and viscosity
  • Suction lift

Positive Displacement, Centrifugal, and High-Pressure Pumps From Highland Equipment

Depending on your specific application, you can choose between positive displacement, centrifugal, and high-pressure pumps. They each offer different capabilities and strengths under particular processing circumstances. Highland Equipment is your ideal partner for high-quality centrifugal, positive displacement, and high-pressure pumps for sanitary processes. Contact us today to select a pump best suited for your application.

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