Vacuum Pumps: Oil-free Alternatives

Vacuum is an integral part of many laboratory processes, but costs associated with generating a vacuum, such as process costs, user costs and cost to the environment, have never really been considered seriously. Although technology has advanced to provide smaller, cleaner and quieter options, not many people are taking advantage of it. “Vacuum pumps last a long time and many people go through their careers without actually buying one,” says Peter Coffey, vice president of sales and marketing at Vacuubrand Inc. “Hence, people tend to replace their vacuum pumps with what they have used before and not take the time to find out about the alternatives.”

Vacuum pumps used in laboratories can be classified into two main types—rotary vane pumps, sometimes referred to as oillubricated pumps, and dry (oil-free) pumps. They operate in different ways to create vacuum and aspirate fluids. Centrifugal pumps use centrifugal force to push the fluid through an outlet; metering pumps, such as diaphragm, peristaltic, piston and syringe pumps, pull fluid into a chamber and then push it through the outlet valve; while positive displacement pumps use bellows, piston, rotary lobe and rotary vane to push fluid through a cavity, leaving a vacuum that pulls in more fluid.

Oil-lubricated pumps have been around for many decades, while the oil-free diaphragm pumps are a more recent addition. Although oil-free pumps tend to be one and a half to two times more expensive than oil pumps, there are a lot of advantages to their use as well as significant lifetime savings. First of all, no oil is used, and therefore there is no cause for oil contamination and no necessity for oil change or disposal. Oil-free pumps can be built to be corrosion resistant and hence do not require regular maintenance. “Service intervals on better oil-free pumps exceed 10,000 operating hours,” says Coffey. “If you use your vacuum pump 20 hours a week, 50 weeks a year, that’s 10 years before the first scheduled service!”

The other misunderstanding that leads to the choice of an oillubricated pump is that people think that more vacuum is always better. Oil-free diaphragm vacuum pumps can provide vacuum levels from atmosphere to below 0.5 mbar/torr, whereas oil-lubricated pumps offer high capacities and higher vacuum levels up to 10-3 mbar/torr. “What is more important is matching the vacuum to the application, and almost any application can now be performed using an oil-free pump, with the exception of freezedrying,” says Coffey.

For certain applications he also recommends considering buying a pump with controls that provide a good balance of speed and control. “Even manual controls are better than none, but electronic controls offer huge productivity advantages,” he says. “In many applications, the type of vacuum control used will determine how much scientist time is needed for oversight and how fast the application proceeds.”

It is often very helpful to talk to someone from a vacuum pump company, who can recommend a pump and offer a demonstration about what will be right for your application and budget. There are also interactive online vacuum pump selection guides available that ask a few questions about the planned use for the pump and recommend a series of pumps to satisfy a range of budgets. “It is not a glamorous technology but it is one that can affect the costs, comfort and convenience of your laboratory,” says Coffey.

KNF Neuberger, Inc.
The wireless SC920 series vacuum pump system delivers fast and precise processing, extremely quiet operation and easy regulation of all vacuums—now with exclusive wireless remote control. The wireless touchscreen remote provides full operation of the pump’s different operating modes and functions, allowing for flexibility and optimal use of lab space. The system supports four different operating modes: vessel evacuation, with adjustable pump capacity; constant pressure control, managed precisely to chosen values; automatic detection of the sample’s vapor pressure; and intelligent sequencing of process pressure per your user-defined program. The pump is easy to control with the intuitive user guide: all process parameters are entered and adjusted with the wireless remote control, using the simple touchscreen and user-friendly control knob.
www.knfusa.com 

Pfeiffer Vacuum
The HiPace™ 300 Plus turbopump with 260 liter per second of pumping is designed specifically for extreme low vibration applications. Due to the reduced vibration spectrum, this pump is ideal for use in analytical applications such as electron microscopy and high-end mass spectrometry, as well as many other vibration-sensitive processes. The pumps are inexpensive to operate due to extended service intervals and the improved rotor design gives both high pumping speeds and high gas throughputs in addition to very good compression for light gases. The pump features integrated drive electronics that reduce the need for cumbersome and costly cabling. The use of innovative materials has doubled the service life of the drives while the functional aluminum housing makes the pumps extremely lightweight for easier handling.
www.pfeiffer-vacuum.com

Oerlikon Leybold Vacuum
The SOGEVAC SV16 BI single-stage, oil-sealed rotary vacuum pump is designed for analytical applications that require lownoise operation and compact design. The pump offers equivalent performance in mass spectrometry applications, comparable to two-stage pumps, but with a smaller footprint and at lower cost. The pump can be easily integrated into a wide range of analytical instruments. External exhaust filtration and oil return is not needed, due to the pump’s internal exhaust filter and oil recovery system. In addition, it can operate at all pressures continuously without any add-on accessories. Features include 20.5 CFM operation at 60 Hz, at up to 3.8 x 10-2 Torr ultimate pressure and excellent compatibility as a fore-vacuum pump in conjunction with wide-range turbomolecular pumps.
www.oerlikon.com/leyboldvacuum

VACUUBRAND
The PC3001 VARIO™ is a self-regulating vacuum pumping system. It is a real time-saver, requiring no programming or test runs, even with complex solvent mixtures. (Control electronics also support programmed runs and process documentation.) The PC3001 detects process pressures and continuously adjusts its own pumping speed to maintain optimum vacuum conditions. Precise vacuum control virtually eliminates foaming and bumping, and reduces process times by as much as 30 percent. The system is oil-free and corrosion resistant, and can capture nearly 100 percent of exhaust vapors to reduce atmospheric emissions. Because optimized pumping results in lower average pumping speeds, the PC3001 conserves energy, and offers unusually long service intervals.
www.vacuubrand.com

Tanuja Koppal, PhD, is a freelance science writer and consultant based in Randolph, N.J.

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