Nov 02, 2006

Peristaltic Pumps: Not Just for Labs Anymore

One of the fastest-growing types of positive displacement pumps on the market is the peristaltic pump. Once used exclusively in the lab, this pump has been transformed for use in process control, water treatment and plant production. Yet, many people remain unfamiliar with this evolving technology and its advantages.

The popularity of the peristaltic pump—or tubing pump—can be attributed to its design. An electric motor turns a set of rollers, which compress and release flexible tubing as they rotate. This squeezing action creates a vacuum that draws fluid through the tubing. Because the flexible tubing is the only wetted part, maintenance and cleanup are simple and convenient.

Contamination-Free System

The peristaltic pump creates a contamination-free pumping system. The fluid being pumped remains inside the tubing at all times and thus never comes in contact with any pump gears, seals, diaphragms or other moving parts. As a result, finding a pump compatible with a particular solution is as simple as choosing chemically compatible tubing.

This makes peristaltic pumps ideal for transferring chemically aggressive or abrasive solutions, as well as high-purity fluids. There is no need to worry about corrosion or wear and tear on parts, and no need to worry about contamination. Moreover, most types of pump tubing can be sterilized through autoclaving, gamma irradiation or ethylene oxide gas application, and most systems facilitate steam-in-place and clean-in-place techniques. This ensures complete sterility of the entire pump system with minimal cost.

Simple, Low-Maintenance Operation

Peristaltic pumps are simple to operate and easy to customize. They are self-priming, and many models have interchangeable pump heads that can be mounted in minutes using finger-tightened screws. Engineering advances have yielded designs that allow the tubing even in large process pumps to be loaded or replaced in seconds. In addition, most pumps feature simple controls, with a dial or keypad for speed control, and straightforward menus for programming more complex tasks.

Peristaltic pumps require very little maintenance beyond tubing replacement. Tubing must be replaced periodically to offset reduced flow performance. This procedure typically takes just seconds, which can be an advantage when using the same pump to transfer or dispense different chemicals. When solutions are changed, only the tubing needs to be changed, and the pump can be up and running within minutes.

In addition, many tubing pumps are designed with high ingress protection ratings, which means they can be hosed down for quick, thorough cleaning.

Tubing Materials

Peristaltic pump systems are compatible with a wide range of tubing materials, including silicone, thermoplastics, Viton and even rigid PTFE. There are also newly developed formulations of bilayer or co-extruded tubing—such as the new Masterflex Chem-Durance tubing—in which a long-life tubing material is laid over a thinner inner material that is compatible with aggressive chemicals, resulting in a tubing whose collective properties in a pump exceed those of either material alone.

Many tubing types also meet United States Pharmacopoeia, U.S. Food and Drug Administration, U.S. Department of Agriculture and/or National Sanitation Foundation agency approvals. This makes peristaltic pumps suitable for handling a variety of fluids, from sensitive cell cultures to industrial solvents, and allows the same pump to be used in multiple applications simply by changing the tubing.

Multimedia Pumping Capabilities

In addition to generating enough suction to self-prime, peristaltic pumps create sufficient vacuum to successfully pump most viscous fluids—including those too heavy for other types of pumps. Yet, because these pumps employ a gentle pumping action that leaves solid components of the fluid—including cell walls and particulates—intact, they are excellent for moving sensitive fluids, slurries and suspended solids.

Peristaltic pumps are also used to move liquids, gases and mixed-phase fluids. If gas bubbles are present in the fluid stream (for instance, through outgassing from the solution), they can be pumped right along with the liquid portion without any flow disruption. For this reason, peristaltic pumps also can run dry without damage.

Cost-Effective Operation

Peristaltic pumps are relatively inexpensive to operate. They are cost-effective because they are easy to clean; they are effectively impervious to the most abusive, pump-damaging chemicals; and the same pump can be used for multiple applications. This results in lower labor and maintenance costs, less downtime and increased production.

About the author

Jaime Schaub is product manager in the Fluid Handling business group at Cole-Parmer, proprietary distributor of Masterflex peristaltic pumps and tubing. She can be reached at 847.327.5919, or by e-mail at [email protected].<p>