From: Bruce Van Scoy <brucev**At_Symbol_Here**BRIGHT.NET>
Subject: Re: [DCHAS-L] Cracked fume hood sash
Date: May 9, 2013 6:59:18 PM EDT
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <3A8C48EDD1C95B4695A9E6C912D43DE223B36F1B**At_Symbol_Here**>

I wonder if ALL of the glass is tempered?  Here is why…

During this year’s annual certification of fume hoods, BSCs, etc., we discovered that the filters needed to be replaced in an older BSC, although we did obtain a 10-year useful life from the existing HEPA filters!  During the decontamination, specifically when a vacuum was applied to exhaust, filter and remove the sterilizing agent, we heard the glass break.  After containment was removed, we discovered the glass cracked from the bottom left, to the top center, ending at the bottom right.  Upon closer inspection we observed small glass shards or splinters on the inside of the BSC.  The BSC was taken out of commission/use until the glass was replaced. 

I was under the impression that you could never find glass shards from tempered glass.  The BSC was from a major/common manufacturer and is a common model, although it is 10 years old. 

I have had multiple experiences with architects re-using fume hoods that were older, but in almost 30 years of experience I had not seen anything comparable.  Maybe the questions should be: is the glass actually laminated safety glass (I don’t know when laminated safety glass was required) or most importantly, would the glass in its current condition provide the proper level of protection that should be expected? 

My stance, following the above experience, is that I would take the hood out of service until it is properly repaired. 



From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Debbie M. Decker
Sent: Thursday, May 9, 2013 3:15 PM
Subject: [DCHAS-L] Cracked fume hood sash


A crack has developed in the vertical sash of a 6 ft. fume hood.  Here’s the descriptor from my researcher:


“Back when it occurred, the repair guys came out and their assessment was you would have to cut the venting above my hood to remove the sash, since it's such a tight fit, and so you would need to close the lab for a bit to do the repair.  The repair guy said the crack wasn't a big deal and did not alter the integrity of the sash.  He also said it wasn't a safety violation, which was my main concern.  


Since the crack seemed like a cosmetic problem, rather than safety, and since I'm one in that hood, I figured I would have it repaired later and hopefully work it into a time when the hoods are down.”


I don’t think I like this characterization but I don’t know a whole bunch about laminated safety glass.  What do ya’ll think?



Debbie M. Decker, CCHO

Safety Manager

Department of Chemistry

University of California, Davis

1 Shields Ave.

Davis, CA  95616





Birkett's hypothesis: "Any chemical reaction

that proceeds smoothly under normal conditions,

can proceed violently in the presence of an idiot."





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