This is true. Hydrogen Sulfide has a low PEL of 20 ppm, and is an olfactory desensitizer. Just because you can't smell it anymore, doesn't mean you're not getting whacked above the PEL. Monitoring devices are best.
Sent from my iPhoneGeorge S. Smith IIIThermo Fisher Scientific
On 2012-11-06, at 4:17 AM, "Stephen Stepenuck" <sstepenuck**At_Symbol_Here**NE.RR.COM> wrote:Careful about the "odor threshold": hydrogen sulfide I believe desensitizes the nasal receptors, so anyone exposed to it continually or at least for a while might think it's not there.
Chemical analysis should give a better answer.
Stephen J. Stepenuck, Ph.D.
Professor of chemistry emeritus
Keene State College
Keene NH 03435-2001
Looks very much like that. I assume the sulfide in the cases of the drywall were sub-ppb (below odor threshold)? No detectable rotten egg smell here.
These are all great leads and the power of this list never fails. I will post a best and final determination once we have one.
Sent from my iPhone
On Nov 5, 2012, at 1:59 PM, "Demer, Frank R - (demer)" <demer**At_Symbol_Here**EMAIL.ARIZONA.EDU> wrote:
Does it look like this - see: http://www.americanscientist.org/issues/pub/a-short-history-of-hydrogen-sulfide/
From: Demer, Frank R - (demer)
Sent: Monday, November 05, 2012 11:23 AM
Subject: RE: [DCHAS-L] help w/ mystery scale on exterior of copper pipes
My guess - the scale is copper sulfide from copper reacting with hydrogen sulfide.
Frank R. Demer, MS, CIH, CSP
Health Safety Officer
Industrial Hygiene and Safety
University of Arizona
Department of Risk Management Services
Mailing Address: P.O. Box 210300, Tucson, AZ 85721-0300
Street Address: 220 W. 6th St., Tucson, AZ 85701 (2nd floor, East Bldg.)
Web Address: risk.arizona.edu <http://risk.arizona.edu>
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of scrooks**At_Symbol_Here**PPEPPRO.COM
Sent: Monday, November 05, 2012 10:02 AM
Subject: [DCHAS-L] help w/ mystery scale on exterior of copper pipes
I was recently asked to look at a dark blue scale appearing on the exterior of some copper piping and determine possible causes and if any human health risk is likely. I am asking here primarily for anyone who's possibly seen this blue scale appear in similar installation. I don't want to take anyone's time going deep as this is a paid consulting task and I do have access to other resources (and this one appears complicated.) This group has seen and experienced so much collectively though that I couldn't pass it up as a great sounding board. Then again, most on this list are being rewarded in some manner through the advice, ideas and answers obtained through the group so my shame isn't too unbearable.
Room contains a medium size waste water pretreatment system where you have typical H2SO4, H3PO4 and NaOH for pH adjust. No excessive mists or vapors from these sources are apparent. The room itself is approx. 30'x30'x20' and also contains an industrial sized autoclave/steam sterilizer which is opened after runs and vents essentially to the room. Plants and soil are a portion of matl being autoclaved as well as (I'm afraid) everything up to the kitchen sink. No reported exposure symptoms from anything (yet) while working in room. Copper pipe was new and developed scale rather suddenly but within the first 6 mos of operation in this new AgriBioPharma facility. Fresh copper pipe pieces have subsequently been hung to determine if this is on-going. The blue color had me thinking an H2SO4 reaction w/ Cu but since Cu has a lesser tendency to give up electron than H, Cu wouldn't reduce H+ ion given by what I suspect at best would be a very dil. H2SO4 in air (if any.) Any chance of Cu(II) Oxide being formed on exterior of pipe from anything in room atmosphere and then making reaction with H2SO4 more likely with extremely low atmospheric vapor conc? Any help is appreciated. Thanks, Steve Crooks
Steve Crooks, MS, CIH, CSP
President & Sr. Consultant
People, Property & Environmental Protection, Inc.
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