Gas detection equipment

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1

Originally Posted By: Jim Acord
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I have noticed that there are several discussions related to combustible gas indicators (CGIs) and carbon monoxide (CO) monitors. There are several misconceptions that need to be clarified.


First, who am I? I am considering become a certified home inspector in the State of Indiana. Over the last twenty (20) years, I have either worked for a major gas utility company or one of its subsidiaries. The last subsidiary that I worked for supplied materials and services to it?s parent energy companies. One of those services was the repair and calibration of combustible gas indicators (CGIs), carbon monoxide (CO) monitors, confined space monitors, and oxygen depletion sensors. I have worked on all of the aforementioned units. I have performed literally tens of thousands of calibrations. I authorized by various manufacturers to work on their equipment ? in some cases, I am the only person that is allowed to perform this work outside of their on staff. My input has been sought on the design and operation of various instruments, from various manufacturers. I am a Senior Member in the Instrument Society of America. I am an electrical engineer but I am not a salesman: if you ask me my opinion on an instrument, you get a straight answer.

With regards to gas detectors, currently, most of the discussions on these forums relate to solid-state semiconductor technology. The J and N Enterprise?s Gas-Trac, the J and N Enterprise?s Sensit, the Bacharach Leakator 10, and UEi? Combustible Gas Leak Detector, are examples of this. These instruments are GENERAL gas detectors, i.e. they do not distinguish what type of gas is present nor do they quantify the gas. You don?t know what the gas is nor do you know how bad the leak is! They can be sent into alarm simply by breathing on them. Strong cologne or perfume will set them off.

Does this make them unacceptable or unuseable? No! They indicate the presence of _something_, you just don?t know what.

As for quantifying a gas or properly identifying it, the two most common type of sensors ? right now ? are pellister and solid state sensor (but not a semiconductor). These solid-state sensors are gas-specific and are only cross-sensitive to a handful of similar gases. For example, a methane-calibrated instrument will generally detect propane, butane, pentane, and methane.

2

Originally Posted By: Guest
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C’mon…tell us more

3

Originally Posted By: rpalac
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you got my attention…


what should we be looking for? and why? ![icon_question.gif](upload://t2zemjDOQRADd4xSC3xOot86t0m.gif) ![icon_question.gif](upload://t2zemjDOQRADd4xSC3xOot86t0m.gif)

4

Originally Posted By: Jim Acord
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Anyway, all gas detection equipment needs to be calibrated on a routine basis, whether you do it or you send it to a service center.


Similarly, you should perform a bump test on all of you gas detection equipment. This can be as simple as applying a gas to the detector and documenting that it was functioning correctly.

With regards to carbon monoxide investigations, according to the American Industrial Hygienists Association (or similar hygienist's association), one must bump test your CO detector before the investigation and then immediately following an investigation. Why? Because the sensor could fail during the investigation.

Back to CGIs, the typical new price range of an acceptable unit is between $1100 and $2300. Used ones can be had for less. These
CGIs are typically pump-driven (as opposed to aspirator bulb) units that will quantify a leak from 0.1% LEL (lower explosive limit or level) to 100% GAS. Combination units that contain CO sensor will operate from 0-2000 PPM.

Some of these units can be calibrated to work on methane only, propane only, or either combustible gas.

Typically, these units could be used in barhole investigations. Barhole investigations are used to probe the ground for gas leaks.




Word of caution: just because a major manufacturer sells a product does not make it a good product. I have had countless salespeople show me an instrument that they claimed was just serviced at the factory that I would then apply a certified calibration gas to the sensor, and that instrument was unable to detect that gas!


Also, some instruments are private-labelled for other manufacturers.


I seem to be rambling in various directions... how about some questions to get focused on?

5

Originally Posted By: rchoreyii
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Do you know anything about a TIF 8800


Her's part of the specs

Partial List of Detectable Compounds
Compound Min. detectable concentration

Acetylene 50 ppm Methyl Chloride 5 ppm
Iso-Butane (R600a) 500 ppm Hydrogen Sulfide 5 ppm
Methane 500 ppm Acetone 50 ppm
Ethane (R170) 500 ppm Methanol 50 ppm
Propane (R290) 500 ppm Ammonia (R717) 20 ppm
Ethylene 500 ppm Gasoline 1 ppm
Hydrogen 500 ppm Chlorine 1 ppm
Methyl Ether 500 ppm Carbon Dioxide 500 ppm
Vinyl Chloride 5 ppm

--
Ron Chorey
LAS CRUCES Home Inspections
rchorey@comcast.net
rchoreyii@nm.nachi.org

6

Originally Posted By: Jim Acord
This post was automatically imported from our archived forum.


the TIF 8800 is a general gas detector, i.e. you know that it picks something up, but you do not know what or how bad the leak is. It will most likely, also pick up carbon monoxide. These types of devices will alert you to a potentially hazardous condition but they cannot identify what the condition is.

7

Originally Posted By: phinsperger
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Ok Jim,


So what are some brands and models that you would recommend?

--
.


Paul Hinsperger
Hinsperger Inspection Services
Chairman - NACHI Awards Committee
Place your Award Nominations
here !

8

Originally Posted By: psabados
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Jim


As a HI, when inspecting a dwelling for line leaks, we have an idea of the general fuel type, whether NG, Propane, oil etc. Our job is to indicate if a leak or problem exists. For instance, the TIF 8800 is a leak detector and does an adequate job. Any leak that we find should be reported and referred to a licensed plumber or HVAC person for repair.

My point is that determining the actual amount of leakage rate would go beyond the scope of a normal inspection. If we find a leak it should be pointed out and repaired, any leak is a problem.

CO on the other hand can be found in any dwelling. What are you recommendations on detection, detection equipment and points of testing.

Paul

9

Originally Posted By: Jim Acord
This post was automatically imported from our archived forum.


The CO sensors that attach to a multimeter are generally acceptable if you desire to leave the instrument at the test point for a period of time, such as leaving it in a dwelling overnight, with the furnace running, to determine typical possible exposure to the occupants.


These type of testers are relatively inexpensive.

The pump-driven type of CO detectors, such as a J and N Enterprises Ultra-Trac or a Gas Measurement Instrument Gasurveyor 6 (among others), will quickly determine the level of CO present.

On must realize that background CO could be present. For example, if the current occupants are smokers, the air in the dwelling probably has CO in it. and CO has probably been "infussed" into softer materials (fabrics and possibly wallboard). This comes from anecdotal evidence from Gas Company service people.

Quote:
"As a HI, when inspecting a dwelling for line leaks, we have an idea of the general fuel type, whether NG, Propane, oil etc. Our job is to indicate if a leak or problem exists. For instance, the TIF 8800 is a leak detector and does an adequate job. Any leak that we find should be reported and referred to a licensed plumber or HVAC person for repair. "


This is correct -- and good for you! I am not being sarcastic or a smart alec -- I have had countless conversations with people that have been using various gas detection equipment that use it improperly. Many do not use common sense. I have had a case where a user discovered CO in a totally-electric building, but, because he knew that combustion had to take place for CO to be present, he kept investigating. He determined that the nightly cleaning crew had used a propane-powered floor scrubber. This floor scrubber was malfunctioning. The operator always attributed his headaches to the cleaning solution and not to CO. After cleaning, the cleaning person would then shut up the building, trapping in the CO.


In a similar vein, the TIF and similar products, can have their tick rate adjusted to the situation. You are re-zeroing the instrument. Remember: you are listening for an increasing in the lights and/or ticker.

As mentioned before, I have had countless conversations with people that have been using various gas detection equipment that use it improperly. I have had arguments with people as to how to use an instrument. Some have argued that whenever their, in this particular case, J and N Enterprise's Sensit went off, they knew that it was a CO leak. Although it could have been CO, there was no way to determine with a Sensit exactly what was triggering the ticker/alarm.

Quote:
"CO on the other hand can be found in any dwelling. What are you recommendations on detection, detection equipment and points of testing. "


General investigating procedure:


    [] Start-up the instrument and allow it to warm-up in a known clean air environment.
    [] Remove all non-intrinsically safe electronic items -- pager, cell phone, pda, computer.
    [] Remove anything that could start a spark -- don't wear a windbreaker into the dwelling.
    [] Zero all scales of the gas detector.
    [] Bum test the instrument and document.
    [] Assuming that the instrument passed the bump test, rezero all scales of the gas detector.
    [] With the sample probe held high, enter the dwelling. Start the investigation in the highest level of the dwelling that is readily accessible.
    Slowly progress through the dwelling and finish the initial investigation in the lowest level of the dwelling.
    [] Next inspect for possible leaks at sources of gas/combustion (Look at the gas fire place, gas stove, gas oven, gas water heater, gas dryer, and gas furnace). Investigate with the appliances both off and then on.
    [] Exit the dwelling and make sure that, if the instrument read any readings, that the instrument purges down to zero.




During the investigation, range or cycle through the appropriate ranges of the instrument, i.e. check on the LEL and the CO scales, as appropriate.

If you do detect CO readings, bump test the instrument again and document it.


If I were to get an instrument these are the features that I would look for:


-- LEL
-- %GAS
-- CO
-- Oxygen -- to be used as a configed space monitor
-- Solid state semiconductor to be used to pinpoint leaks
-- Ease of use
-- Ease of calibration


I would want an instrument to be able to be used as a confined space monitor -- I do not like the idea of crawling into a crawlspace and not knowing if there is enought air present for me to breathe.

Additionally, I would like the ability to change gas type from Natural Gas to Propane. I would also like to use readily-available batteries.


BIASED OPINION:

I like the J and N Enterpise's Ultra Trac 2000 and the Sensit Gold CGI. I am factory-authorized to repair and calibrate these instruments and I like them.

I believe that the Senist Gold CGI is the better instrument.

The company that I work for sells these instruments, among others. I do not get a commission off of the sale of this, or any, instrument. I am not looking to generate any sales for the comapny that I work for nor am I looking to benefit from my relationship with J and N Enterprises. I am not trying to gain anything from any of this.

My MAIN CONCERN is that anyone using any gas detection equipment is using it properly and is maintaining it properly.
10

Originally Posted By: psabados
This post was automatically imported from our archived forum.


Jim


Great posts and very good information. By the way! Welcome to the BB, hope you keep posting.

Thanks again

Paul

Counting down the days to Orlando 2005 T-minus 157 and counting!

11

Originally Posted By: rpalac
This post was automatically imported from our archived forum.


Hi Jim,


All are welcome to express there knowledge on this web site.


Some are factual and some are very biased. In either case we listen and learn.


Your information is very good for me to hear and research more knowledgeably. I believe that's what were shooting for.

I hope others read this thread and chime in on there experience and perspective.

Some one like you who as an indepth knowledge of the workings of an instrument is very valuable to us all. Thank you for trying to help us learn.

Don't stop.

Bob P.