Vacuum Pumps: Size, Capability, Green Factors, And More Come Into Play

Scientists started using true vacuum pumps more than 350 years ago, and investigators used suction pumps for more than 400 years before that. Consequently, removing gas to create a vacuum is not new in science. Nonetheless, the way of removing that gas keeps changing. “There’s a movement away from house-vacuum systems and toward smaller lab systems or dedicated individual pumps, partly for energy efficiency,” says Roland Anderson, laboratory products manager at KNF Neuberger (Trenton, NJ). “This change provides vacuum where it’s really needed.” Other experts agree. For example, Peter Coffey, vice president, marketing and sales, Vacuubrand (Essex, CT), says, “We have noticed that a lot of new science buildings do not include central vacuum systems.”

Part of that transition arises from the complexity of central systems. “A central vacuum relies on a couple of very large pumps, usually in the basement, that provide vacuum to lab benches through a network of pipes that run throughout the entire building,” Coffey explains. In some cases, though, simpler solutions create their own problems.

Waste With Water

One of the simplest ways to create a vacuum involves water. A Venturi vacuum pump, or aspirator, uses running water to create a vacuum. In fact, a Lab Manager survey published in July 2012, reported that 36 percent of the respondents still use aspirators in their labs. Coffey adds, “I recently heard of a major research facility that is being built without a central vacuum supply and for which the scientists plan to use aspirators.”

Although aspirators seem like a simple fix in some cases, these devices can make poor choices. As Coffey points out, aspirators “waste and pollute massive amounts of water. For example, a single water-jet aspirator used 10 hours a week in a lab will waste 45,000 gallons of water a year, and contaminate it with solvent vapors as it does so.” He adds, “Water-jet aspirators are much cheaper than buying a vacuum pump, but the operating cost and environmental impacts more than offset the purchase cost savings—in some areas in a year or two.”

Selecting A System

Lab designers still select large systems in some cases. “Though they are inefficient and not costeffective, house vacuums are still very popular when developing new research buildings with dedicated lab space,” Anderson says. “When renovating labs, scientists are considering smaller, local multi-user vacuum systems or individual pumps for common laboratory applications.”

Coffey says that central vacuums get bypassed for several reasons. “The vacuum from a central system is one-size-fits-all, even though chemists, biologists, and physicists all need vacuum of a very different character,” Coffey says. “In the modern multidisciplinary science building, the different disciplines need different vacuum.” That’s not all. Coffey adds, “The different requirements of the different scientific disciplines often end up leading to conflicts, with the uses made by one discipline compromising the vacuum characteristics needed by other scientists.”

A central system can even create environmental problems in some cases. “The vacuum system sucks vapors into the walls, so there is risk of cross-contamination between labs and condensation of toxic vapors in the piping,” Coffey says. As Anderson mentioned above, central systems also use more energy. In some installations, the pumps for a central system run all the time, even when no one is in the building.

In addition, individual pumps provide more flexibility over time. “With a fixed installation,” Coffey says, “the vacuum utility cannot adapt as the science, space needs, or budgets dictate.” Individual pumps even keep labs up and running longer. “If there’s a problem with such a system, only one pump needs to be changed,” Anderson says.

Some vendors also offer systems that bridge central and individual vacuum pumps. Jacquie Richardson, Ph.D., director of organic chemistry teaching labs at the University of Colorado at Boulder, describes using such a system: “Each student bench has a connection. The one downside is that if one student leaves their vacuum spigot open, it messes things up for the other students at their bench.” She adds, “That’s easy enough to remedy with [teaching assistant] oversight, though.” Overall, she says that she’s very pleased with such a system.

Transitions In Technology

Beyond moving from aspirators to pumps, the technology inside the latter even changes. For example, rotary vane pumps use oil and others use a diaphragm, which is oil-free. Anderson calls the oilfree approach greener, adding that it “provides enough vacuum for many labs.”

With rotary vane pumps, Anderson says, working with wet vapors “gets moisture in the oil and it starts to break down, like the oil in your car.” Then the oil needs to be changed and the old oil must be disposed of, and it can be contaminated by the vapors.

Although Anderson points out that rotary vane pumps supply higher flow and deeper vacuum than diaphragm pumps, he says that the latter provides enough suction for most applications. Nonetheless, he adds that researchers still need rotary vane pumps for some applications such as lyophilization.

When it comes to evolving vacuum-pump technology, other features also matter. As Coffey says, “Users often are looking for a quieter pump than they have, because vacuum pumps are often one of the noisiest pieces of equipment in the lab.” Many users agree. For instance, Faleh Salaymeh, staff scientist II at Relypsa (Santa Clara, CA), wants a vacuum pump that is accurate, durable, reliable, and quiet. He says, “I like the silence or quietness of [our pump’s] operation, considering it is running all day in a laboratory with personnel around.” His system also includes a remote control pad that he calls “a welcome addition.”

In the end, picking the right vacuum pump changes life in the lab and beyond.

For additional resources on vacuum pumps, including useful articles and a list of manufacturers, visit www.labmanager.com/vacuum-pumps