Fume Hood Performance as a Function of Laboratory Air Supply

Thomas Smith, Exposure Control Technologies, Inc.

A laboratory hood system provides protection for hood users by containing, capturing, and exhausting hazardous airborne materials generating within the enclosure. Fume hood containment can be affected by numerous variables such as the aerodynamics of the hood, average face velocity, and cross drafts near the hood opening. Numerous studies have indicated that improper air supply can produce potentially devastating cross drafts near the hood opening. However, there is little information evaluating hood performance as a function of the type of air supply diffuser, location of the diffuser with respect to the hood, and the discharge volume. A study was conducted to evaluate the affects of different air supply diffusers on fume hood performance. Fume hood performance was tested using methods described in the ASHRAE 110 "Method of Testing Performance of Laboratory Fume Hoods" while supplying air to the laboratory through different diffusers from various manufacturers over a range of supply air volumes.

This presentation describes the results of the tests and recommendations for specification of air supply diffusers that complement hood performance.

Biography:

Thomas C. Smith is the President of Exposure Control Technologies, Inc. Mr. Smith is a leader in laboratory safety and energy management. He specializes in helping laboratories provide safe, dependable, and energy efficient operation of laboratory hoods and ventilation systems. He holds a Bachelor of Science degree in mechanical engineering from North Carolina State University and a Master of Science degree in environmental engineering from the University of North Carolina.

Mr. Smith is active in developing national and international standards for laboratory ventilation and serves as Chairman of ASHRAE TC9.10 Laboratory Systems and Vice Chairman of ANSI/ASHRAE 110 Fume Hood Testing. He is also a member of ANSI/AIHA Z9 Standards for Ventilation and Health.

Since 1985, Mr. Smith has participated in hundreds of laboratory ventilation projects and evaluated thousands of laboratory hood systems. His work has improved the safety of laboratory environments and saved millions of dollars in energy costs. He currently provides technical consultation to numerous Fortune 100 companies, top research universities, and government agencies on the forefront of environmental safety and energy conservation.

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