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Product Focus: Fume Hoods

Fume hoods are notorious for consuming expensive resources, particularly electricity and conditioned air that is vented to the environment along with volatile chemicals and other toxins.

Angelo DePalma, PhD

Angelo DePalma is a freelance writer living in Newton, New Jersey. You can reach him at

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Ductless Models at Forefront of “Green” Lab Movement

Fume hoods are notorious for consuming expensive resources, particularly electricity and conditioned air that is vented to the environment along with volatile chemicals and other toxins. Luke Savage, an engineer at Labconco (Kansas City, MO), describes traditional hoods as “huge energy hogs.”

A decade ago, low-flow hoods revolutionized the industry by reducing air throughput and related energy costs by 40 percent. According to Jon Zboralski, director of air flow products at Thermo Fisher Scientific (Two Rivers, WI), the industry still considers low-flow hoods “new” despite their ten years on the market and hard evidence that they can save facilities as much as $2,400 per year per hood.

More recently, ductless hoods changed the equation yet again in favor of greater energy efficiency and cost savings.

Ductless fume hoods use activated carbon filters to remove toxins from the airstream. Unlike traditional hoods, which vent tens of thousands of cubic feet of heated or air-conditioned workspace per day, ductless fume hoods return conditioned air to the lab. “This translates to a significant drop in energy use,” observes Kevin McGough, president of AirClean Systems (Raleigh, NC). Compared with “feel-good” sustainability initiatives, ductless hoods can save significant operating costs while protecting the environment.

Other significant trends

Equipment longevity also plays into the idea of a “green” laboratory. Although fume hoods do not “wear out” like other laboratory fixtures, they have a finite usable life. Customers, according to Mr. McGough, pay close attention to quality, materials of construction, and anticipated product lifecycle. In response, fume hood manufacturers have embraced the use of polypropylene, a specialty of AirClean. Compared with metal, polypropylene offers advantages of corrosion resistance and seamless/ gapless construction.

AirClean customers have been requesting mobile fume hoods to accommodate expanding or changing workflows and to avoid the costly construction costs associated with vented hoods. “Ductless solutions are key here,” Mr. McGough says, as they need not be connected to the facility’s HVAC system and may be moved from one work area to another in minutes. The only requirements are an electrical outlet and at least six inches of clearance from the ceiling.

Traditionalists may recoil from the idea that chemical-laden air can be cleaned and returned to the work area. Manufacturers are quite aware of this and have bent over backward to demonstrate that ductless technologies are safe and work as advertised.

AirClean, for example, employs sophisticated safeguards including an industry-standard metal oxide detector, photoionization gas detection, an “acid array” that monitors gas saturation at ppm levels, and an onboard chemical database to validate an application’s compatibility with ductless filtration. The company’s Independence model even features an energy-conservation mode that further reduces energy use.

A ductless fume hood requires no ductwork, arrives fully assembled, and may be installed in locations where, barring a significant and expensive renovation process, a traditional fume hood could not.

Enabling filter/ adsorption technology

At the time of their introduction, ductless hoods were limited by their filtration systems, which tended to be application-specific. “If you used formaldehyde, you needed a filter specifically designed for removing formaldehyde,” says Mr. McGough. Ductless designs were therefore marketed to labs that were highly protocol-driven, where one or several operations using the same chemical reagents were carried out repeatedly and exclusively, or to elementary and high school labs. “Dedicated” applications are still the principal market for ductless hoods.

That is changing rapidly with the 2009 debut, from Erlab (Rowley, MA), of Neutradine molecular filtration, a type of super-activated carbon that is nearly a universal chemical absorber. Neutradine incorporates binding sites for various chemical families, and neutralizes acids as well. Independent tests have demonstrated that this filtration medium removes 98 percent of all chemical fumes used by 99.9 percent of laboratories. Erlab has partnered with Thermo, Airmaster, and ALC Collegedale to supply Neutradine media for ductless hoods.

Karl Aveard, VP of Green Fume- Hood Technologies at Erlab, recognizes that environmental health and safety professionals have been wary of ductless hoods and that the technology may not be appropriate for heavy-duty organic chemistry or isotope labs. “A bias has developed over several decades against filtration versus venting,” he admits.

Thermo’s Jon Sboralski puts it succinctly: “The idea makes people queasy, and that’s totally expected.”

But Erlab has worked hard to convince users and facility personnel that ductless hoods are for real. “We have installations at a number of top universities and are working closely with the EH&S community as well as architects and lab planners. So far they like what they see and plan to be early adopters.”

Angelo DePalma holds a Ph.D. in organic chemistry and has worked in the pharmaceutical industry. You can reach him at