Yes, a hood can have good containment with only 60 fpm face velocity, but that can be reliably achieved only with extremely good design and maintenance of the entire room in which the hood is placed. In my opinion, simply buying a hood that claims to demonstrate good containment at 60 fpm, without reference to the details of its intended location, is folly.
Peter Zavon, CIH
I have tried to be brief here. I've got a lot of data on this question.
Taking a larger view, I have found this face velocity question has become a commercial as well as a lab safety issue.
Any public institution interested in sustainability needing fume hoods wants competitive bids. Generally speaking, then, the question usually asked is "what face velocity is necessary for a variety of competitive companies to be able to offer low-bid units which will pass ASHRAE 110?"
I am in agreement with the 80-120 FPM numbers cited in other responses when this is the actual question. The irony is, if a hood costs more but can get great containment results at, say, 60FPM should it be considered and how does one alter the low-bid context to allow such a hood to be considered? It has been demonstrable for years that more than a few very low exhaust hoods can offer safe containment and show a very low COST OF OWNERSHIP over the hood's lifetime. This long term view has, unfortunately, little to do with the way public sector lab exhaust equipment is bid, even given the increasing influence of sustainability.
I note several respondents are open to face velocities lower than 80 FPM, provided they work. This is a great start to expanding our safety and commercial philosophies simultaneously.
Very Truly Yours,
Dr. Bob Haugen
Director of Product and Technology Development
Flow Sciences Inc.
2025 Mercantile Drive
Leland, NC 28451
Phone 910 332 4878
By a quick show of hands, what face velocity do all of you consider as an acceptable velocity for certifying standard chemical fume hoods in academic and research labs? OSHA is pretty vague on the issue (must provide adequate ventilation [1910.1450(e)(3)(iii)]). Appendix A (non-mandatory) references Prudent Practices, where 80-100 is standard, up to 120 is okay for high hazard (no containment benefit proven) and 60fpm may be okay for low flow, specially designed hoods.
Before getting into too much detail, I am curious as to what all of you are considering as passing at 18in sash height, and what you are considering as failing.
Brandon S. Chance, M.S., CCHO
Associate Director of Environmental Health and Safety
Office of Risk Management
Southern Methodist University
PO Box 750231 | Dallas, TX 75275-0231
T) 214.768.2430 | M) 469-978-8664
"- our job in safety is to make the task happen, SAFELY; not to interfere with the work-" Neal Langerman
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