If it were me, in a research environment NOT in California (since their regulations specify face velocity), I want the hood to demonstrate capture and containment of vapors. This can be checked using smoke inside and around the sash edge, and one of the following:
1. For semi-quantitative, more objective data: A photoionization detector and an organic solvent such as acetone, hexane or whatever the PID will respond to. IF you use glacial acetic acid (below) and the PID, you'll need an 11.6 eV lamp. Check the concentration inside and outside the hood.
2. For a qualitative check, a watch glass and a few mL of glacial acetic acid or concentrated ammonium hydroxide will provide ample evidence of containment. I've never encountered a an individual that cannot detect the odor or glacial HAc or ammonium hydroxide.
It's been my experience that hoods with less than about 70-75 fpm; likewise hoods greater than about 230 fpm will fail as well.
My 2-cents. Your mileage may vary.
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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