How the Albert Einstein College of Medicine safely handles fume hood exhaust at 300 laboratory workstations
Educational research centres with extensive laboratories in urban areas face special problems with regard to safely exhausting sensitive laboratory workstations, particularly biosafety level (BSL) labs. This was the case at the Albert Einstein College of Medicine of Yeshiva University in New York City, a four million square foot facility where 300 laboratory workstations are employed for a variety of cutting edge medical research applications. In addition to the obvious indoor air quality (IAQ) issues to be managed in this critical environment, because Einstein’s buildings are located in an urban setting, major concerns focused on efficiently and safely exhausting the fume hoods at its laboratory workstations.
According to Peter Pessoni, Assistant Director of Operations and Maintenance at Albert Einstein, the institution had requirements in new buildings of healthy IAQ as well as safe, legal atmospheric exhausting. The Samuel H. and Rachel Golding Building’s mechanical systems were designed by Cosentini Associates, New York City mechanical, electrical, plumbing engineers who suggested use of Strobic Air Tri-Stack® mixed flow impeller laboratory exhaust systems to replace traditional, individually dedicated mushroom-type fans on the roof, each of which was connected to a tall, unsightly rooftop stack. “Tall roof exhaust stacks generally create a negative perception of a neighbourhood polluter,” commented Pessoni, “It was the first time we had used Tri-Stack systems for managing our laboratory workstation fume hood exhaust.”
There are eight laboratory floors at Einstein’s Golding Building. Each workstation’s fume hood (with integral HEPA filter) is ducted into a common plenum to a cluster of mixed-flow impeller systems on the building’s roof. Several other laboratory research facilities at Einstein now also have Tri-Stack mixed-flow impeller systems on its roof; including, the 20717 sq.m. Michael F. Price Centre for Genetic and Translational Medicine/Harold and Muriel Block Research Pavilion and the six-storey Irwin S. and Sylvia Chanin Institute for Cancer Research. As for the type of research accomplished at Einstein, Pessoni called it, “Cutting edge medical research including studies on cancer, HIV, diabetes, and more.”
In determining the best approach for managing the college’s laboratory workstation exhaust, Pessoni worked closely with Cosentini which specified detailed wind studies as part of its evaluation process. Wind studies are a necessary prerequisite in urban location applications such as this where re-entrainment of sensitive or odorous laboratory workstation exhaust fumes might cause potential problems in the laboratories as well as in adjacent buildings and are often used to predict exhaust air flow under a wide variety of atmospheric conditions. Wind studies using empirical data were conducted to determine how the Tri-Stack mixed-flow impeller systems would perform in this environment as well as the most appropriate uses of these systems with regard to the laboratories’ exhaust requirements.
In discussing the mixed flow impeller systems at Einstein, Pessoni said there are 22 individual Tri-Stack fans mounted in “cluster groups” on the buildings’ rooftops, with eleven on the Chanin building, three on the Golding building, and eight on the Price building. Fans in each group are served by common plenums, a configuration that maximizes their effectiveness. The individual Tri-Stack fans at Einstein are rated at various capacities from 500 to 7800 m3/hr, with electric motors from 1.5 HP to 30 kW. Because of their low profile design, the fans are unobtrusive on the roofline, typically 4m. high, and eliminate the perception of a “neighbourhood polluter” commonly associated with tall exhaust stacks on the roof.
Mixed-flow impeller systems work by mixing outside (ambient) air with exhaust discharges to essentially dilute the exhaust stream at the roofline and send it in a powerful vertical plume hundreds of feet above the building. This technology, which has been in use throughout the world for many decades, provides a number of significant advantages for a variety of exhaust applications in addition to laboratory workstation fume hoods. (See Mixed flow impeller technology – operation and advantages)
In addition to the benefits offered by the Tri-Stack systems for Einstein’s laboratory workstation fume hood exhaust systems, Pessoni also commented that because the systems incorporate high efficiency fan blade design and low horsepower motors, they are able to operate continuously on significantly less power which helps reduce energy costs. And speaking of energy consumption, mixed-flow impeller systems of this type are also used at many laboratories and chemical/pharmaceutical processing facilities that require conditioned 100% makeup air. In these applications these systems can help reduce heating and cooling costs substantially. While the systems at Einstein are not used for this purpose, many universities with laboratory workstations are seeking relief from high energy costs via this technology, especially since laboratory facilities account for unusually high energy consumption. Mixed-flow impeller systems in these applications add warm and/or cool air to ventilation intake air in order to achieve substantial energy reductions within the facility.
During the evaluation period for determining the best approach to manage its laboratory workstation fume hood exhaust, Pessoni and his associates at Einstein considered at least four discrete goals: these included ensuring worker safety with regard to IAQ; complying with appropriate standards and codes for discharging its laboratory workstation exhaust; and a “good neighbour” policy to prevent exhaust re-entrainment. They also had to achieve these goals without generating objectionable noise levels at the property line and in the laboratories, while consideration of the roofline profile and its related aesthetic issues were also factors. “All of these goals were achieved with the acquisition of the Tri-Stack mixed-flow impeller exhaust systems” Pessoni concluded.
Based on case study written by Paul A. Tetley, Vice President and General Manager at Strobic Air Corp; a subsidiary of Met-Pro Corp, Harleysville PA, USA.
Strobic Air Corporation (www.strobicair.com) is a recognized technological leader in the air movement industry, specializing in advanced exhaust systems for laboratory fume hoods at universities, public health institutions, wastewater treatment facilities, government agencies, and chemical, pharmaceutical, industrial, and other process industries. With over four decades of experience managing critical requirements of laboratory researchers and facility owners, Strobic Air has continued to develop and enhance its Tri-Stack® mixed flow technology roof exhaust systems to provide greater flows, reduced energy costs, decreased noise levels, and compliance with all appropriate air pollution standards. The company also offers complete engineering, design, and technical support for its Tri-Stack systems and accessories, including a unique fan selection program to help provide practical, common sense solutions for pollution abatement and odour control applications. Strobic Air Tri-Stack systems help prevent re-entrainment into existing or neighbouring facilities, eliminate odour, reduce noise at the property line (through its fan silencers), and comply with architectural and aesthetic standards.
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