A variety of chemicals and general organic solvents, including hazardous anti-neoplastic agents such as formaldehydes, acetones, and toluenes, are employed at the workstations. But not only was re-entrainment a critical issue, another problem concerned the high maintenance associated with the existing centrifugal fans. According to Bruce Styles, the assistant director at the Department of Occupational and Environmental Safety for New York, "the belt driven fans were a headache. There were constant belt changes required, which caused downtime problems at individual workstations."

While many alternative approaches were reviewed by the New York State Dormitory Authority, owners of the Institute, the solution ultimately came from Strobic Air's Tri-Stack laboratory fume hood exhaust systems. Claudatos-Parks said that, "the State Department of Environmental Protection obviously knew what performance parameters it required with regard to air quantities and static pressures, and it used the Tri-Stack systems to meet these requirements as well as eliminate the re-entranment problems."

Peter M. Bognar, at Fancher Sales Co., Inc., in Buffalo, represented Strobic on the project and worked closely with Styles and his superior, Michael J. Murphy, director of the Department of Health, Occupational and Environmental Safety for the state.

"The system (Tri-Stack) is a clean solution that the customer is happy with."

Bognar said that 15 Strobic Air Model BS-I Tri-Stack systems were mounted on the roof of the facility with the existing centrifugal fans remaining as back-ups but capped off. Clusters of four to six centrifugal fans had been grouped together sharing a common plenum. To speed installation and reduce costs, individual hood risers were tied into the Tri-Stack systems.

Bognar said that, "the air intakes were high on the building and lab workstation effluents were being reentrained into them." This was caused mainly by the centrifugal fans "not pushing the air or effluent high enough above the building envelope to get away from being brought back into the ventilation air intakes," he added. Air quality outside the building was a major concern as well, since there is also a 150-bed hospital building at the

"It took education in both the product (Tri-Stack) and the concept to show our clients the value."

complex. So the idea of using stack extensions with architectural enclosures (penthouses) for the existing centrifugal fans was also rejected because of inefficiency and high cost.

Roswell's building management people were pleased with the Tri-Stack solution. Styles said that the maintenance-free operation of Tri-Stack systems "helps keep maintenance

"Air quality is a primary concern at the facility. The whole environment is controlled and monitored."

people off the rootãa particularly sensitive issue at the Cancer Cell Center."

The Tri-Stack design suited everyone involved, according to Claudatos-Parks. "The whole environment" has to be controlled and monitored, she said. "Facilities engineers want efficiency and cost-effectiveness...the 50 existing fume hood exhausts were easy to manifold using the Tri-Stack systems," she added.

Styles said that, when a "more traditional'? solution to the original problem_ was considered, "with regard to placing fans in a penthouse where maintenance can be performed in foul weather, it clearly did not present a viable alternative." And when "building costs, architectural designs, ductwork configurations and resultant static pressure losses were calculated, " Styles added, "the costs were prohibitively expensive."

Tri-Stack systems drastically reduced energy consumption

The 15 Tri-Stack replacements at Roswell Park's Cancer Cell Center are composed of eleven systems with 5 HP motors, and four systems with 10 HP motors, providing a total CFM of 120,000. The Center's previous centrifugal fans ranged from 675 to 2150 CFM, with most in the 900-1400 CFM range. The Tri-Stack systems have cut 75 horsepowerãwith associated energy reduction, of courseã over alternate replacement designs. By also eliminating multiple guy wires that require frequent adjustment, roof mounting hardware that can cause leaks, ductwork restructuring with resultant static pressure losses, and new construction for fan penthouses and building extensions, substantial additional cost savings were realized.

We wrote the guidebook (and produced the t video) on safe, efficient laboratory ventilation. Both are yours for the asking. Call or fax for copies, technical data, or applications advice. For design/applications tips, visit our web site: http://www.strobicair.com E-mail: tristack@strobicair.com