Guest guest Posted December 28, 2005 Report Share Posted December 28, 2005 Curtis, What occupant symptoms are you referring to from exposure to methane at 5ppm, or are the symptoms from something else? The odor threshold of the mercaptan additive is about one (1) ppb. I have also found plenty of natural gas leaks after the gas company had told the customer (in residential and commercial buildings) that they did not find any. I just use my nose. It's more sensitive. If I smelled a very strong odor of mercaptan upon entry to the building, I would leave and call the gas company immediately. How can you have 5ppm methane from natural gas leaks and not know it from the mercaptan smell? Steve Temes I've consistently found occupants to be symptomatic at concentrations of about 5 ppm (measured as methane) and up. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 28, 2005 Report Share Posted December 28, 2005 Jeff and Group, The gas utility companies (at least around here) use a CGI for indoor measurements. They also have FIDs, but their policy is to only these when outdoors. The CGI has a lower detection limit of .5% or 5,000 ppm. The TIF 8800 Combustible Gas Detector is economical, and has a detection range of 50-1000 ppm. Historically, though, I've consistently found occupants to be symptomatic at concentrations of about 5 ppm (measured as methane) and up. I use a ThermoElectron TVA 1000B dual FID and PID. At $10,825, it's quite a bit more expensive than the TIF 8800 ($210). On the other hand, it's kind of like comparing my Dri-Eaz WetChec ($35) to my Protimeter SurveyMaster ($450) moisture meters. Both will tell me if something is wet, but the Protimeter can tell me more about the conditions. Sometimes it is really beneficial to have the extra info. Since the TVA is a dual detector, I can compare the readings between the PID and FID. The PID actually doesn't detect methane, whereas the FID " loves it " . I can rule out a lot of possible VOC sources and focus on the natural gas system if the PID doesn't change (caution: PID false responds to water vapor) and the FID is climbing above 5 ppm. Maybe not a concern in most situations, but I've found several homes where methane concentrations actually exceeded the LEL (these were " routine " IAQ investigations, not HazMat calls!). Nice that the TVA is also intrinsically safe and didn't provide an ignition source. I've seen a gas utility technician get blown across a room (after disregarding my warnings) and I think I'd prefer to pass on anything more " up close and personal " . Whether the economical combustible gas detector (provided the detection limit is low enough) or the more expensive FID, I think it makes a lot of sense to check for the " big numbers " before going to the time and expense of looking for ppb VOC levels. " When you hear hoofbeats, think horses, not zebras " (Occam's Razor). Curtis Redington RE: TVOC sampling > > > Ditto Bob. > > The noise to signal ratio does not allow adequate use of these instruments. (We own a Field PID and an FID and an FTIR and I have owned 2 GCs. Etc....) > > Tony > > > .......................................................................... > " Tony " Havics, CHMM, CIH, PE > pH2, LLC > PO Box 34140 > Indianapolis, IN 46234 > > cell > FAIR USE NOTICE: This site contains copyrighted material the use of which has not always been specifically authorized by the copyright owner. We are making such material available in our efforts to advance understanding of environmental, political, human rights, economic, democracy, scientific, and social justice issues, etc. We believe this constitutes a 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit to those who have expressed a prior interest in receiving the included information for research and educational purposes. For more information go to: http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 28, 2005 Report Share Posted December 28, 2005 As a final thought, if we can suspect MVOC's (or other VOCs) in the ppb range as causing irritant reactions, why is it so difficult to consider methane at ppm concentrations? Curtis, Not difficult to consider. I would even consider the ppb concentrations of the mercaptan from the gas leak as being the cause of headaches rather than the methane. The human body reacts to the sulfur-based compounds having low odor threshold values at the "reptile brain" level. I would theorize that the reason these compounds have such a profound impact at low concentrations is because it is a hardwired olfactory nerve-mediated survival mechanism (i.e., don't eat rotten food). The body's hormonal or neurological response might very well result in increased blood pressure and/or vasoconstriction causing headache. Steve Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 28, 2005 Report Share Posted December 28, 2005 Steve, It appears that the mercaptan odor can be "scrubbed" from natural gas (and propane) under a variety of conditions. Many, many times I have found significant gas leaks with little if any odor. Like you, I use my nose, but sometimes the odorant just isn't there. Other times the mercaptan odor may be masked by other conditions (like a house full of cats). Like many other conditions we deal with on a regular basis in IAQ, there may be more anecdotal evidence than hard science. Not to seem to cynical, but if you compare what the agriculture lobby has been able to do with ammonia, it doesn't seem too much a stretch to consider the influence of the natural gas industry when it comes to methane. What I can emphatically state is that most of the time when a caller reports headache as their primary symptom, I'll get an FID detector response of 5 ppm or more at their front door, and find natural gas leaking into the building. Fix the gas leak and the symptoms go away. Too many times and too diverse a population to write off as psychosomatic. I've got physicians that will refer chronic headache patients to me. Not always, but often, I'll end up finding a gas leak in the home. As the gas concentration goes up, additional symptoms such as nausea and then dizziness are reported. Theron Grant Randolph, MD is credited with linking natural gas exposure (along with other environmental exposures) to adverse health symptoms in the early 1950's. He eventually became a staunch advocate for MCS, which (according to some reports) resulted in much of his work being tucked away in the sometimes "fringe" area of "environmental medicine". I've been making observations on this for 12 years and haven't come up with any other explanations that seem to fit. I'm willing to listen to good argument, though, if someone thinks I'm wrong. As a final thought, if we can suspect MVOC's (or other VOCs) in the ppb range as causing irritant reactions, why is it so difficult to consider methane at ppm concentrations? Curtis -----Original Message-----From: iequality [mailto:iequality ]On Behalf Of AirwaysEnv@...Sent: Wednesday, December 28, 2005 2:43 PMTo: iequality Subject: Re: Re: TVOC samplingCurtis,What occupant symptoms are you referring to from exposure to methane at 5ppm, or are the symptoms from something else? The odor threshold of the mercaptan additive is about one (1) ppb. I have also found plenty of natural gas leaks after the gas company had told the customer (in residential and commercial buildings) that they did not find any. I just use my nose. It's more sensitive. If I smelled a very strong odor of mercaptan upon entry to the building, I would leave and call the gas company immediately. How can you have 5ppm methane from natural gas leaks and not know it from the mercaptan smell?Steve Temes I've consistently found occupants to be symptomatic at concentrations of about 5 ppm (measured as methane) and up. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 30, 2005 Report Share Posted December 30, 2005 Tony, No MSDS. It comes with a caution label -- "If the fog causes skin, eye, or nasal irritation, discontinue use. Fog may cause asthmatic reaction in highly sensitive individuals. Not food. Not intended for internal consumption." It further states that the ingredients are commonly used in food, drugs, and cosmetics and have been tested by an independent laboratory. It's probably all food grade. Compared to the sulfuric acid mist and titanium tetrachloride smoke tubes I've been using over the years, this will be a comfort to work with in someone else's home or building. I've gagged a couple of clients pretty good with the smoke from these tubes and once stained a new stainless steel lab bench when I set a sulfuric acid tube down on it for a while. Steve Temes Does it come with an MSDS? and if so, does it list an exposure limit for PG? Tony ........................................................................... "Tony" Havics, CHMM, CIH, PE pH2, LLC PO Box 34140 Indianapolis, IN 46234 cell 90% of Risk Management is knowing where to place the decimal point...any consultant can give you the other 10%? This message is from pH2. This message and any attachments may contain legally privileged or confidential information, and are intended only for the individual or entity identified above as the addressee. If you are not the addressee, or if this message has been addressed to you in error, you are not authorized to read, copy, or distribute this message and any attachments, and we ask that you please delete this message and attachments (including all copies) and notify the sender by return e-mail or by phone at . Delivery of this message and any attachments to any person other than the intended recipient(s) is not intended in any way to waive confidentiality or a privilege. All personal messages express views only of the sender, which are not to be attributed to pH2 and may not be copied or distributed without this statement. Re: Re: TVOC sampling For those of you who have not tried Bearg's suggestion of using the Wizard Stick ($14.95 at www.zerotoys.com) to generate smoke, give it a chance. The smoke isn't exactly non-bouyant, but the propylene glycol and glycerine in this kid's toy are a lot safer than other chemical smokes. Got mine yesterday. It's not ready for the Professional Equipment catalog or SKC yet, but with a little tweaking and better packaging/presentation it sure has potential. It takes a little practice to get a steady stream of "smoke" going. The smoke dissipates quickly but I like it a lot. And you have to be careful to enunciate the name :-) Steve Temes Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 30, 2005 Report Share Posted December 30, 2005 Does it come with an MSDS? and if so, does it list an exposure limit for PG? Tony ........................................................................... "Tony" Havics, CHMM, CIH, PEpH2, LLCPO Box 34140Indianapolis, IN 46234 cell90% of Risk Management is knowing where to place the decimal point...any consultant can give you the other 10%â„ This message is from pH2. This message and any attachments may contain legally privileged or confidential information, and are intended only for the individual or entity identified above as the addressee. If you are not the addressee, or if this message has been addressed to you in error, you are not authorized to read, copy, or distribute this message and any attachments, and we ask that you please delete this message and attachments (including all copies) and notify the sender by return e-mail or by phone at . Delivery of this message and any attachments to any person other than the intended recipient(s) is not intended in any way to waive confidentiality or a privilege. All personal messages express views only of the sender, which are not to be attributed to pH2 and may not be copied or distributed without this statement. -----Original Message-----From: iequality [mailto:iequality ] On Behalf Of AirwaysEnv@...Sent: Friday, December 30, 2005 10:05 AMTo: iequality Subject: Re: Re: TVOC sampling For those of you who have not tried Bearg's suggestion of using the Wizard Stick ($14.95 at www.zerotoys.com) to generate smoke, give it a chance. The smoke isn't exactly non-bouyant, but the propylene glycol and glycerine in this kid's toy are a lot safer than other chemical smokes. Got mine yesterday. It's not ready for the Professional Equipment catalog or SKC yet, but with a little tweaking and better packaging/presentation it sure has potential. It takes a little practice to get a steady stream of "smoke" going. The smoke dissipates quickly but I like it a lot.And you have to be careful to enunciate the name :-)Steve Temes Quote Link to comment Share on other sites More sharing options...
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