Kim, I'm not sure how they do this in chemistry, but in art we just follow the ACGIH ventilation manual. For example, if the painting class will have 20 easels, if the solvent is a particular petroleum distillate, and if the rate of use in ounces/hour/student is estimated, then we only need to know the physical characteristics of the solvent (e.g., molecular weight, TLV, etc.) and we can plug it into the formula to determine what the dilution rate must be.
If that calculated dilution rate is too high to be reasonably provided, we have to look at changing the solvent, reducing the rate of use, cutting the number of students in the class, or doing administrative controls such as having some of the painters use acrylic or water-washable oils rather than solvent-based oil painting. And if they want to do high-solvent-use techniques such as solvent washes where the whole canvas is covered with solvent at one time (4-6 ounces depending on canvas size), then we need a local ventilation system like a walk in spray booth for this process.
If you want to see those calculations, contact me off the forum and I'll send them to you. And it is these calculations that help me get art teachers to understand the incredible savings in ventilation and energy costs if the switch to safer solvents or go to solvent-free painting products. The teacher must understand the limits of the ventilation systems provided.
It is simply wrong to set a ventilation rate for any chemical use room without clearly established limits on the processes and materials used there. That's what's wrong with ASHRAE standards in general.
Monona Rossol, M.S., M.F.A., Industrial Hygienist
President: Arts, Crafts & Theater Safety, Inc.
Safety Officer: Local USA829, IATSE
181 Thompson St., #23
New York, NY 10012 212-777-0062
From: Kim Gates <kim.gates**At_Symbol_Here**STONYBROOK.EDU>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Sent: Mon, Nov 10, 2014 11:53 am
Subject: [DCHAS-L] Lab ventilation & hazard assessment
I posted this awhile ago & haven't heard - thought I'd try again.
Does anyone have a good method for documenting the ductless hood ANSI Z9.5 requirement for a "hazard evaluation & analysis conducted as directed in ANSI/AIHA Z9.7 and SEction 18.104.22.168"?
Does anyone have a written guide to evaluate lab work & decide when a fume hood is required?