Years ago, furniture manufactures used to make hoods. They were just a box with air flowing through them but today, aerodynamics may just play the most important part in hood design and performance. We are using a variable flow fume hood that keeps face velocity constant when the sash aperture is changed. These are made by Flow Safe Industries and are tested with no spillage at face velocities of 40fpm. Their aero dynamic interior sets up a horizontal vortex that they have developed and patented. Flow safe considers OSHA requirements as well as, NIOSH, NFPA, ANSI, ASHRAE recommendations and other mitigating factors when designing their fume hoods (i.e. explosion (ignition/pressure) considerations, height/size of worker, need for vertical sash movement, roller for sash windows at top (not bottom),GFCI outlets, and more) . As an EHS professional, I am impressed with this manufacturer. I am in no way affiliated with Flow Safe and receive no compensation for this testimonial. Variable flow hoods save energy with no compromise to hood performance.
As for lead time, in a facility with over 200 fume hoods, it took about 10 years from conception to completion, with major funding form the local power authority for the energy savings component. The actual fume hood conversions/new installations took about 1 year before testing for all by ASHRAE 110 method could begin.
Of course, like anything, you get what you pay for, therefore, hoods with additional services, metal as opposed to plastic parts, longer length, etc. – the pricing will increase. One thing I did learn is that they will not manufacture walk in hoods any longer because it is very difficult to prevent them from spilling under all conditions.
Of course, manifold system, types of fans, location of hoods with respect to traffic patterns are also major considerations. Quite a discussion to start, with very little guidance from 29CFR1910.1450, Occupational Exposure to Hazardous Chemicals in Laboratories, I thought I see more responses today.
James Saccardo, CHMM
From my experience as a formulator of solvent borne coatings and adhesives, even the best designed and constructed fume hood will not function efficiently if it is not installed properly, including proper design of the infrastructure (e.g., make-up air of the laboratory and facility).
Greater Chicagoland Area
I would like to start a discussion on current experience with chemistry fume hoods related to overall quality, best value, interior construction, coatings/materials of construction, installation issues, air flow alarms, order lead time, energy saving features plus anything else that comes to mind.
James S. Johnson Ph.D., CIH, QEP
JSJ and Associates
Pleasanton, CA 94588
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