As can easily be demonstrated with a simple smoke generator (or evaporating dry ice) a linear velocity of 150 f/m usually causes excessive turbulence/eddy currents that can cause escape of vapors from the hood to the user's breathing zone. Here are some examples of standards established by others. I choose these because they are information-rich with respect to explanations of different types of hoods (and their components), and the standard conditions under which linear velocity is measured.
http://www.stanford.edu/dept/EHS/prod/mainrencon/Labdesign/Section_1-1_Ventilation.pdf See comprehensive bibliography of regulations & stnds. Average 100 lfmp.
http://ehs.columbia.edu/fhPolicy.html 80-120 lfpm120
http://www.colorado.edu/ehs/pdf/ECIH.FumeHoodQandA11_08.pdf 80-120 lfpm
http://www.usg.edu/ehs/guidelines/lab_design/v.phtml 80-120 lfpm
http://web.princeton.edu/sites/ehs/labsafetymanual/sec6b.htm#performance >100 lfpm
http://www4.uwm.edu/usa/safety/laboratory_safety/fumehoods.cfm > 100 lfpm
David Haugen (retired)
From: "Patricia Peifer"
I am not currently the person who is responsible for our lab fume hood testing, our metrology department does that. They wrote a procedure for this task but did not include an upper limit for face velocity. I was cited for this when we had an outside safety audit done, with the recommendation being that we have a upper limit for fpm of 150. Previous post | Top of Page | Next post
Sent: Thursday, January 26, 2012 2:46:04 PM
Subject: [DCHAS-L] Chemical Fume Hoods
This made sense to me, my understanding was that an upper limit of 150 fpm (or even 120) was generally standard. I would like to learn more about ventilation and take over responsibility of the fume hood testing at my facility.
My question is:
• Is training highly recommended or even required to test chemical fume hoods?
• Does anyone have a recommendation for training?
• Should I indeed be looking at 150 fpm as an upper limit? I have looked at ANSI, NRC, etc., but have not purchased the actual documents.
Pat Peifer, CHO
Safety and Chemical Hygiene Specialist
West Pharmaceutical Services
101 Gordon Drive
Lionville, PA 19341
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I am not currently the person who is responsible for our lab fume hood testing, our metrology department does that. They wrote a procedure for this task but did not include an upper limit for face velocity. I was cited for this when we had an outside safety audit done, with the recommendation being that we have a upper limit for fpm of 150.
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