The Case for Dedicated Laboratory Vacuum Systems

by Roland Anderson, Laboratory Products Manager, KNF Neuberger, Inc.

The demand for a reliable vacuum source has led to several different vacuum pump solutions. Many large industrial and academic labs traditionally use a centrally located house vacuum system. House vacuums normally consist of a large, powerful vacuum pump designed to distribute vacuum throughout the facility using an installed piping network. The system uses several in-line traps to protect the pump from aggressive solvents and hazardous vapors. Users tap into the system through outlet valves located on the bench and/or in fume hoods.

Laboratory Design Practices

A recent survey of architects, engineers, builders and consultants identified “right sizing” of mechanical systems, including vacuum systems as the top technical issue in lab design. As conserving energy becomes more important for sizing lab utilities, specifying a house vacuum system with enough power to provide high vacuum at every bench is considered wasteful. Increasingly, labs are turning to dedicated stand-alone pumps as an alternative to the expensive house vacuum systems.

Traditional Vacuum Sources

Oil-sealed rotary vane pumps have been used extensively in chemical and biological research since they mimic the performance of the house vacuum system in a smaller, less expensive option. The rotary vane pumps use vanes mounted on a rotor inside a circular cavity to develop a vacuum by positive displacement. Special oil blends are used to lubricate and seal the vanes during operation. Regular pump maintenance and the disposal of contaminated pumps oils prove costly and are in opposition to ‘Green’ initiatives.

Water Aspirators

Some academic labs still rely on water aspirators to satisfy their vacuum needs. The most popular water aspirator is a cheap and simple Tee fitting that attaches to a faucet. The water then flows through a restriction in the Tee that creates the venturi effect and develops a vacuum at the side arm. The vacuum level varies with changes in water pressure and temperature. Water aspirators are cheap to purchase but expensive to own. Wasting and polluting drinking water is expensive and harmful to the environment.

Oil-Free Diaphragm Pumps

For common lab applications, oil-free diaphragm pumps provide reliable vacuum performance in a clean, corrosion resistant package. Diaphragm pumps use a reciprocating membrane and inlet and outlet check valves to provide a vacuum through positive displacement. No expensive lubricating oils or drinking water/drain are required to develop a vacuum, making diaphragm pumps truly clean and dry. In addition, these pumps can be made from highly corrosion resistant PTFE materials making them ideal for use with aggressive solvents and chemical hazards. Some models, such as KNF’s LABOPORT®, (shown above as a stand-alone vacuum system with a pump controller) use advanced valve systems that can encounter occasional liquids without affecting performance or causing damage.

Conclusion

For many labs it makes financial sense to use oil-free, diaphragm vacuum pumps as an alternative to rotary vane pumps and water aspirators. Since they do not require running water or create contaminated waste they are truly economical and environmentally friendly. In comparison to house vacuum systems, diaphragm pumps are inexpensive to own and operate. Most importantly, they provide vacuum when and where it is needed, while consuming a fraction of the energy used by a house vacuum system.