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Warnings for Users of Toxic Gas Measurement Instruments InspectAPedia ® Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Warnings about using instruments for detection of toxic gases
• Recommendations for gas measurement instruments, gas detector tubes, Draeger & Gastec, Komyo Rikagaku Kitagawa, RAE, & Sensidyne gas detection tubes & pumps for detection of gases

This document outlines warnings for people using gas detection tools and sensorsused to test for the level of toxic and other gases in buildings and in outdoors. In related documents we give references and explanation regarding toxicity of several of the most common indoor gases, based on literature search and obtained from the U.S. government and expert sources. This text may assist readers in understanding these topics. However it should by no means be considered exhaustive. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

Warnings about Relying on Instruments for Detection of Hazardous Gases in Buildings

OPINION-DF: In 1991, for ASHI, the American Society of Home Inspectors I authored or edited several articles on the use of instruments to test for evidence of dangerous flue gas leaks such as carbon monoxide in residential buildings. We were excited by the possibility of improving the level of safety afforded by a professional home inspection by permitting home inspectors to use instruments to perform simple screening tests for toxic or dangerous carbon monoxide gas leaks. Inspectors were already using the TIF 8800 described above, but that wide spectrum instrument could not focus specifically on, nor give numeric levels of carbon monoxide gas alone.

Quite a few home inspectors rushed to buy and some continue to use any of a variety of excellent and sensitive specialized pocket-sized gas detectors designed to screen specifically for carbon monoxide. Particularly in parts of the U.S. where home inspectors had found that the level of expertise offered by their local gas distribution companies was a bit weak, they were anxious to have a more reliable safety check tool for buildings heated by natural or LP gas.

In my view these articles encouraging the use of carbon monoxide detection instruments in the hands of some of these home inspectors was a disaster. Home inspectors who were not technically inclined, home inspectors who were more focused on the bottom line (profit), and inspectors who were looking for a way to simply speed up their inspection while doing less work, simply purchased one of these instruments, turned it on, and left it to check the heating system for CO leakage while they, being efficient and fast fellows, went off to inspect something else.

In other words, some home inspectors stopped inspecting the heating system as thoroughly as they had before relying instead on the instrument to do their work for them. Those inspectors, thinking that their job was done, simply reported that the instrument did or did not detect any carbon monoxide, and they disclaimed further responsibility for the condition of the heating equipment or even for the accuracy of the test they had performed. What was wrong with this approach?

• A complete visual inspection of the heating system, flue vent connector, chimney externals, controls, and safety devices is essential to form a reasonable opinion about the condition, usability, and safety of a heating system. Use of an instrument to check for the presence of a single gas is an inadequate substitute.
  
  
• The production of dangerous carbon monoxide varies enormously at a given heating system over a short time and for a variety of reasons. Testing with a door to the boiler room or furnace room open or shut can completely change the supply of combustion air (in some cases) and thus can "turn on" or "turn off" the production of dangerous carbon monoxide.
  
  
• Many other safety operating defects may be present and may be very important besides the test for carbon monoxide release.

In sum, there is a place for and good use for test instruments during building investigation, but they are not and should not ever be a substitute for a careful and thorough visual inspection and history-taking by an expert. Those "high speed" inspectors would have performed a better service for their clients by encouraging them to purchase and install smoke detectors and home-use carbon monoxide detectors than to hasten their inspection by using an unattended CO instrument in the home. Our article CARBON MONOXIDE - CO includes a photograph of a simple and effective carbon monoxide detector intended for homeowner installation and use.

Warning: About Selecting the Proper Gas Detection Tube

Gas Tube and Gas Pump Must be Compatible

Colorimeteric gas detection tubes produced by different manufacturers are not necessarily interchangeable among gas detection pumps. Be sure that the gas detection tube you are using is one recommended for use with your gas detection pump - check both the gas detection pump manufacturer's instructions and the gas detection tube manufacturer's specifications.

For example, as we were informed in May 2008 by Nextteq Gastec^TM detection tube distributor in the U.S., Gastec tubes that are currently available are not intended for use on the Sensidyne^TM gas detection pump.

At one point in time, Sensidyne had the contract for Gastec tubes and lost it due to rebranding.  The tubes they sell now are Kitagawa tubes, not Gastec.  We don't want to confuse anyone out there that they can use a Gastec tube with the Sensidyne pump.  The Gastec tubes are not calibrated to work with a Sensidyne pump and therefore, the reading could be incorrect and prove fatal in some cases.\

Gas Tube Must Be Properly Sensitive to the Gases Being Investigated

Be sure to select gas detection tubes designed to detect the proper gases being screened in a building, and also to select the gas detector tube which is calibrated to detect gases at the proper level of concern. The detection of many gases is supported at varying levels of sensitivity. Selecting a tube which is not sensitive enough may result in failing to detect the presence of the target gas. Selection of a gas detection tube which is too sensitive may result in inability to accurately detect the actual level of gas which is present since the tube will become saturated before the actual gas level has been recorded.

Technical Reviewers & References

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - InspectAPedia.com ^TM Website Author/Editor
• Jennifer Moore, Sales Administrator, Nextteq, LLC, Tampa FL, www.nextteq.com 813-249-5888. Nextteq is the master Distributor for Gastec in the United States. According to the company's website, Gastec Gas Sampling Pumps are the industry’s first and only pumps to provide on-the-spot measurement of ambient temperature. [Private email, JM to DF 5/23/08]
• "Choosing and Using a Carbon Monoxide CO Monitor," Dan Friedman, The ASHI Technical Journal, Vol. 2 No. 1, July1991
• "Heat Exchanger Testing, Who's Right?" Dan Friedman, The ASHI Technical Journal, Vol. 2 No. 1, July1991
• "Case History: LP Gas Leak - Using the TIF 8800," Dan Friedman, The ASHI Technical Journal, Vol. 2 No. 1, July1991
• Chimneys, Flues, Woodstoves & Fireplaces: Safety Concerns, safe and proper venting of combustion gases, carbon monoxide hazards
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

CARBON MONOXIDE - CO
CARBON DIOXIDE - CO₂
OXYGEN - O₂
GAS MEASUREMENT TOOLS
  Use of a Drager pump
  How Colorimetric gas detection tubes work
  Using the TIF 8800 Gas Detector
  Using the TIF 5000 Gas Detector
  Warnings re instruments for detection of gases
  Warning: choose the right tube for gas detection

More expert information on this topic

More Information on Toxic Gas Detection, Exposure, Test Procedures, Toxicity, and Remedy, & Building Diagnostic Inspections and Repairs

Toxic Gas Exposure Hazards and Test Protocols including links to our toxic gas exposure screening and gas testing protocols.

Gases: Toxic gases, indoor exposure levels, testing, identification

• A Toxic Gas Testing Plan: A Gas Sampling Plan for Residential and Commercial Buildings lists some of the toxic indoor gases for which we test, depending on the building complaint and building conditions
• Gas Exposure Hazard Levels: for Toxic Gas Exposure to Ammonia, Arsine, Arsenic, Bromine, Carbon Dioxide, Carbon Monoxide, Hydride, Ozone - allowable exposure levels and hazard levels
• Carbon Dioxide Gas Toxicity hazard level, poisoning symptoms, & testing
• Carbon Monoxide Gas Toxicity hazard levels, poisoning symptoms, & testing
• Formaldehyde: US EPA. UFFI (Urea Formaldehyde Foam Insulation) was previously considered a hazard (formaldehyde outgassing). Subsequent research virtually closed concern regarding this material; however formaldehyde appears to remain a health concern for sensitive individuals.
• Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
• Sampling for gases in air such as VOC's, MVOC's, toxic chemicals, and combustion products.
  Unfortunately no single test or tool can detect all possible building contaminants. We use methods and equipment which can test for common contaminants. If the identity of a specific contaminant is known in advance we can also test for a very large number of specific contaminant gases in buildings.
  We use gas sampling equipment provided by the two most reliable companies in the world, Draeger-Safety's detector-tubes and Drager accuro bellows pump, the Gastec cylinder pump and detector-tube system produced by Gastec. We also have used gas detection tubes by Gastec previously marketed for use with Sensidyne pumps but Sensidyne pumps now use Kitagawa gas detection tubes. We also use Sensidyne's Gilian air pump. For broad screening for combustibles and a number of other toxic gases and for leak tracing we also use Amprobe's Tif8850 and 8800, and the TIF 5000 automatic halogen leak detector (for air conditioning and cooling system refrigerant leak detection). All of these instruments, their applications, and sensitivities (minimum detectable limits) for specific gases are described in our Gas Sampling Plan online document.
• Radon Gas U.S. EPA Radon level maps

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