Designing lab ventilation to emerging standards.

Designing a ventilation system for a laboratory is challenging not only because these facilities consume a lot of energy and may contain materials that are toxic, flammable, explosive, infectious, or radioactive, but because standards and codes concerning them are revised often to reflect stricter health and safety requirements and improvements in technology.

Dilution calculations for determining laboratory exhaust stack heights.

Laboratory exhaust stacks should be designed with sufficient height and exit momentum to avoid re-entry of exhaust and possible air quality problems, and the design should be evaluated before construction. One evaluation method is presented in this paper that combines dilution prediction equations from the 1997 ASHRAE Handbook-Fundamentals (1997} and a dilution criteria of Halitsky (1988). This method is less conservative than a geometric method in the ASHRAE Handbook and is less costly than wind-tunnel modeling.