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  1. #1
    Ron Bishop's Avatar
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    Default Carbon Monoxide detector 1 ft. above floor

    During the inspection of this house, I cam across a carbon monoxide detector in the hallway, that was placed 1 foot above the floor. I have always seen them at ceiling level. Does anyone have a good explanation for this?
    Thank you kindly

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  2. #2
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    CO is slightly heavier than air, so the lower location is actually better.


  3. #3
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    that's what I was wondering...thank you


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by Vern Heiler View Post
    CO is slightly heavier than air, so the lower location is actually better.
    Not trying to nit pick your post here Vern.

    CO2 is heavier than air and will fall to the ground.
    CO is slightly lighter than air and will rise and move with natural air currents.

    A plug in location for a CO alarm is the worst location possible in a home.
    They should be placed at eye level on each floor of a home, preferably in the bedrooms.

    Keep in mind that a UL 2034 rating on a CO alarm makes it pretty much useless to begin with.

    Measured Performance more than just a buzzword

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    Default Re: Carbon Monoxide detector 1 ft. above floor

    From the scientists:

    Carbon Monoxide and Density


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    I stand corrected.

    Thanks.


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by Rick Hurst View Post
    From the scientists:
    Yep, that is pretty much what I expected. A lot of figures, statistics and then "it doesn't really matter" and "use common sense" conclusion.

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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by Gunnar Alquist View Post
    Yep, that is pretty much what I expected. A lot of figures, statistics and then "it doesn't really matter" and "use common sense" conclusion.
    After all that he was corrected.

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    Default Re: Carbon Monoxide detector 1 ft. above floor

    As I recall from my CO training several years ago, and explained in Rick's reference, CO is lighter by 1 molecule. So while there is technically a difference, it is a very small one and air movement that is in the home will overcome it.

    What is advised is keeping the detectors out of corners and if on walls, not up against the ceiling. I am aware of no requirement that restricts low placement. One consideration that is seldom mentioned - dead end hallways. At night, when bedroom doors are likely to be closed, air movement can be substantially reduced and delay CO's reaching a detector at the far end of the hall.

    Eric Barker, ACI
    Lake Barrington, IL

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    Default Re: Carbon Monoxide detector 1 ft. above floor

    When all else fails...read the directions (if you have them). The instructions for mine said to mount it 3 feet above the floor on the wall.

    Go figure

    Bruce Thompson, Lic. #9199
    www.TylerHomeInspector.com
    Home Inspections in the Tyler and East Texas area

  11. #11
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    hhhmmm...who da thunk bout readin direcshuns


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Read the levels they alarm at while you're reading those directions.

    Measured Performance more than just a buzzword

  13. #13

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Good morning, Gents:

    As a scientist, let me wade in and address a few things. The whole notion of whether CO (or CO2) is heavier than air or lighter than air is simply not important for a lot of reasons.

    For a start, heavier-than-air gases don’t settle to the lower portion of a structure and lighter-than-air gases don’t accumulate at the upper areas of a building. That's a myth.

    Posit: Imagine for a moment that one could “see” helium (a lighter-than-air gas), and imagine that it was blue. And imagine for a moment that one could “see” toluene vapor (an heavier-than-air gas), and imagine that it was yellow. Now, take an air-tight see-through chamber made of glass, of say, ten cubic meters, that contains “air.” Carefully displace the upper portion of the chamber with helium so that the upper one foot layer is all blue. Now carefully displace the lower portion of the chamber with toluene, so that the lower one foot layer is yellow.

    Now imagine that the chamber has absolutely NO ventilation, and absolutely NO air movement, and in fact, the chamber is isothermic so there are no convection currents. Now, wait an hour, and guess what? The contents of the chamber is green – the blue layer will be gone and the yellow layer will be gone!

    What happened? As the two different gases were being introduced into the chamber, the mass density of the material was different relative to the displaced material (the air), and so even visually, one could see a distinction, and the displaced material was occupied preferentially by another material. However, what you could not see was that the blue helium as also immediately mixing with the air, and so was the yellow toluene. The molecules don't "know" they are heavier or lighter than their surrounding neighbors; they are in constant motion, and are busy zinging along a straight path until they hit another molecule which changes their direction. The molecules are NEVER stationary, but are in constant motion.

    “Air,” helium, and toluene vapor (just like oxygen, carbon monoxide, carbon dioxide, etc) are “ideal gases” and they will completely and perfectly occupy any given volume at EXACTLY the same concentrations. So, after a few minutes, no matter where in the chamber we measure the concentration of gas, it will be the same as in all other areas of the chamber.

    So although the helium temporarily occupied the upper portion of the chamber, and the toluene temporarily occupied the lower portion, within a very short period of time, through the process of molecular diffusion, the two gases mixed perfectly.

    Now, if that can happen quickly in an air-tight chamber with no convection currents, imagine how much more quickly perfect mixing will occur in an open structure with air movement.

    The proper placement of a CO meter in a property has more to do with occupancy, proximity to a combustion source, topography of the structure, thermal by-passes, and so forth. Each of these parameters vastly overwhelms any consideration of molecular weight.

    Which brings me to a pet peeve of mine: I go nuts when the commentators during an NFL game talk about the hang time of flight of a ball during game in the fog or rain, wherein the presumption is made that the ball is hindered in flight by the high humidity, since the commentators foolishly believe that the air is “thicker” due to the high humidity. In fact, moist air has a lower density than dry air (that is, water vapor is a lighter-than-air-gas).

    Cheers!
    Caoimhín P. Connell
    Forensic Industrial Hygienist
    Forensic Industrial Hygiene

    (The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

    AMDG


  14. #14
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    I love reading your posts Caoimhín

    The only problem with that is I am not a know it all of all topics discussed so as far as I know you may have no idea what you are talking about

    Just kidding. It all makes perfect Sense to me. Besides, I do know it all. I think!

    Love your posts.


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by Caoimhín P. Connell View Post
    Good morning, Gents:

    As a scientist, let me wade in and address a few things. The whole notion of whether CO (or CO2) is heavier than air or lighter than air is simply not important for a lot of reasons.

    For a start, heavier-than-air gases don’t settle to the lower portion of a structure and lighter-than-air gases don’t accumulate at the upper areas of a building. That's a myth.

    Posit: Imagine for a moment that one could “see” helium (a lighter-than-air gas), and imagine that it was blue. And imagine for a moment that one could “see” toluene vapor (an heavier-than-air gas), and imagine that it was yellow. Now, take an air-tight see-through chamber made of glass, of say, ten cubic meters, that contains “air.” Carefully displace the upper portion of the chamber with helium so that the upper one foot layer is all blue. Now carefully displace the lower portion of the chamber with toluene, so that the lower one foot layer is yellow.

    Now imagine that the chamber has absolutely NO ventilation, and absolutely NO air movement, and in fact, the chamber is isothermic so there are no convection currents. Now, wait an hour, and guess what? The contents of the chamber is green – the blue layer will be gone and the yellow layer will be gone!

    What happened? As the two different gases were being introduced into the chamber, the mass density of the material was different relative to the displaced material (the air), and so even visually, one could see a distinction, and the displaced material was occupied preferentially by another material. However, what you could not see was that the blue helium as also immediately mixing with the air, and so was the yellow toluene. The molecules don't "know" they are heavier or lighter than their surrounding neighbors; they are in constant motion, and are busy zinging along a straight path until they hit another molecule which changes their direction. The molecules are NEVER stationary, but are in constant motion.

    “Air,” helium, and toluene vapor (just like oxygen, carbon monoxide, carbon dioxide, etc) are “ideal gases” and they will completely and perfectly occupy any given volume at EXACTLY the same concentrations. So, after a few minutes, no matter where in the chamber we measure the concentration of gas, it will be the same as in all other areas of the chamber.

    So although the helium temporarily occupied the upper portion of the chamber, and the toluene temporarily occupied the lower portion, within a very short period of time, through the process of molecular diffusion, the two gases mixed perfectly.

    Now, if that can happen quickly in an air-tight chamber with no convection currents, imagine how much more quickly perfect mixing will occur in an open structure with air movement.

    The proper placement of a CO meter in a property has more to do with occupancy, proximity to a combustion source, topography of the structure, thermal by-passes, and so forth. Each of these parameters vastly overwhelms any consideration of molecular weight.

    Which brings me to a pet peeve of mine: I go nuts when the commentators during an NFL game talk about the hang time of flight of a ball during game in the fog or rain, wherein the presumption is made that the ball is hindered in flight by the high humidity, since the commentators foolishly believe that the air is “thicker” due to the high humidity. In fact, moist air has a lower density than dry air (that is, water vapor is a lighter-than-air-gas).

    Cheers!
    Caoimhín P. Connell
    Forensic Industrial Hygienist
    Forensic Industrial Hygiene

    (The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

    AMDG
    With all due respect I would have to disagree to a certain extent to some of the above comments.

    I have no doubt your above post is based on perfect science and formulas but I can only speak on what I've seen and measured in the field.

    When I see a spilling water heater go from safe levels of undiluted CO to unsafe levels in a manner of minutes due to O2 displacement at the burners it makes me wonder why.

    At the same time when I've gone into buildings and measured higher CO concentrations in air pockets at upper levels of a structure compared to the lower levels I again have to wonder why.

    Great post.

    Measured Performance more than just a buzzword

  16. #16

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Good evening, Gents:

    OK, let’s approach it from a different angle.

    Go back to our chamber, but this time let’s just use two gases: “air” and toluene. Toluene is heavier than air, in fact, it is immensely heavier than air; about three times heavier than air.

    So let’s take our chamber filled with air, and fill the bottom portion with just toluene gas. Now we have a one foot deep layer of toluene in the bottom, right? Good. Now, if we hook up a manometer and read the pressure differential across the shell of the chamber, we would see that the gases in the chamber are at equilibrium – no net pressure between the top and the bottom, and since the chamber is not pressurized (it’s just holding the gases, like a cup holds air), there is no net pressure differential across the wall of the chamber.

    See below:



    Now let’s carefully suck out the air above the layer of toluene. If the toluene is resting on the bottom of the chamber because it has settled there (since it is heavy), it should just remain there, right?

    See the chamber below:



    But look what has happened to the pressure differentials. The toluene is still exerting the same pressure as before, as expected, but now, there is a vacuum in the top part of the chamber. How could you possibly have a pressurized chamber at the bottom, and a perfect vacuum at the top?

    Answer: You can’t.

    The toluene will expand into the top layer to fill the vacuum. In fact, the toluene doesn’t know what the pressure is at all … because it, like all perfect gases, will perfectly fill any volume in which it is placed and it will extert the EXACT same pressure on the walls of the container regardless of the original pressure in the container – this is known as Pascal’s Law.

    The actual pressure in the chamber is described by an equation known as the ideal gas law: PV=nRT. (pressure times volume equals the number of moles of gas times the ideal gas constant times the temperature).

    If this were not the case, then remember this: “Air” itself is a mixture of gases that are lighter-than-air, and heavier-than-air: Taken as an whole, “air” would have an equivalent gram molecular weight of about 28; diatomic oxygen (heavier than air at 32 gmw) is 20.9%; CO2 (44 gmw, at 0.03%); diatomic nitrogen is 28 gmw at 78%, and argon at 40 gmw contributes about 1%.

    So if a chamber were filled with “air,” and gases separated out according to their “weights,” an enclosed chamber would quickly partition out in layers, with CO2 settling to the bottom, upon which a layer of argon would rest; which would be covered by a layer of oxygen, capped by a layer of nitrogen. There is not a single reader of this board who would expect to see that happen – so why would any of you expect that CO, with a gmw of 28 would “settle out?’

    DavidR – the answer to your observations lies in the last part of my post “The proper placement of a CO meter in a property has more to do with occupancy, proximity to a combustion source, topography of the structure, thermal by-passes, and so forth. Each of these parameters vastly overwhelms any consideration of molecular weight.” Similarly, the measurements you observe also depend on those parameters.

    Ted: In fact, my ignorance is overwhelming. Presume I have absolutely no idea of what I am talking about. So take the info on its own merits – it will either stand or fall on its own merits, the credibility of the poster notwithstanding!

    Dang – I need another beer!

    Cheers!
    Caoimhín P. Connell
    Forensic Industrial Hygienist
    Forensic Industrial Hygiene

    (The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

    AMDG


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by Caoimhín P. Connell View Post

    DavidR – the answer to your observations lies in the last part of my post “The proper placement of a CO meter in a property has more to do with occupancy, proximity to a combustion source, topography of the structure, thermal by-passes, and so forth. Each of these parameters vastly overwhelms any consideration of molecular weight.” Similarly, the measurements you observe also depend on those parameters.
    Wow, once again, excellent post.

    My questioning comes not from CO alarm placement but from what I've viewed occurring during the combustion process with a combustion analyzer and my own eyes.

    This leads me to think that what I am seeing is more of a timing issue than an air mixing issue.

    Have to admit it has me wondering if the CO2 is spilling at a greater rate than it can mix with the ambient air and be dispersed evenly.

    Would be interested in your thoughts on this.

    Measured Performance more than just a buzzword

  18. #18

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Good morning, DavidR:

    During our indoor air quality investigations, we are frequently asked to calculate the mixing factor or decay rate for a given study area, (this are normal standard studies while investigating IAQ issues). To do this, we release a quantity of a known material and measure the concentration over time.

    Often, we will use CO2; dropping a couple of pounds of dry ice into a five gallon bucket (very scientific), can quickly raise the CO2 concentration in an office setting to 5,000 ppm.

    As we drop the blocks of dry ice into the bucket, one can literally see the CO2 spilling down the outside of the bucket, and spilling out along the floor (for a short distance). It does this primarily because it is very cold, and therefore dense, and therefore it “sinks.” While this is occurring, the highest concentrations of CO2 are found along the ground.

    Air currents, ventilation system, normal convection cells and the movement of occupants quickly increase the mixing and disrupt the temporary layer of CO2. However, in practical terms, the CO2 NEVER reaches equilibrium in all parts of the room – why not?

    A standard indoor air quality algorithm used to model concentrations of airborne materials is given as:



    Wherein:
    Ct is the dynamic concentration (C) at any time (t);
    Co is the original (starting) concentration;
    Q is the amount of outside air being brought into the room via ventilation;
    V is the volume of the study area-
    k is the mixing factor.

    The last term, k, is the reason that we never see equal concentrations in any study area, Pascal’s Law notwithstanding. The air in a room is always in motion, and there are two competing parameters: Sources and Sinks. Sources are supplying contaminant into the system, and Sinks are removing the contaminant.

    The term k can range from 0.1 for a normal living room to 0.999 for a large empty airplane hanger with massive fans stirring the air in all directions. So, whenever one measures the concentration of something in the air, there are two huge variables: spatial variations and temporal variations.

    There reason your measurements vary is because you are using a single measuring device, in a single location at a specific moment in time. By moving the device around, you will get differing readings (spatial variations); by keeping the device in one place, you will get differing readings (temporal variation).

    One of my normal activities (whether I am measuring the airborne concentrations of mould spores, radon, or even determining the methamphetamine concentration in an house), is to be able to walk into a structure and be able to at least qualitatively determine the k, and determine where airflow is going, and why.

    Having said all that, by the way, it is also important to know that most home CO monitors on the market (such as the ones originally under discussion in this thread), don’t actually measure CO!

    Cheers!
    Caoimhín P. Connell
    Forensic Industrial Hygienist
    Forensic Industrial Hygiene

    (The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

    AMDG


  19. #19
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Thank you for the clarification, again excellent information.
    Thank you for taking the time to share.

    I agree with you 100% on the state of CO monitoring, the best option I've seen at a reasonable cost to date is electrochemical and these are even bound by the UL 2034 standard.

    Measured Performance more than just a buzzword

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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by Caoimhín P. Connell View Post
    Having said all that, by the way, it is also important to know that most home CO monitors on the market (such as the ones originally under discussion in this thread), don’t actually measure CO!
    So what are they measuring or detecting?

    Thanks for the interesting information.

    Bruce Thompson, Lic. #9199
    www.TylerHomeInspector.com
    Home Inspections in the Tyler and East Texas area

  21. #21

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Hello Bruce:

    I own a couple of CO monitors which actually measure the concentration of CO in the air. The net result is that if the CO concentration goes from 23 ppm to 25 ppm in one second, my monitors will similarly respond and will display a reading of 23 ppm and then 25 ppm.

    However, most of the CO detectors folks are using in their homes, would exhibit no change at all, and most would not even indicate an elevated condition. That’s because most CO detectors folks are using in their homes, are actually responding to a dynamic time (times) concentration curve (T * C), that mimics human blood disassociation curve for carboxyhaemoglobin (COHb).

    COHb is the haemoglobin whose shape becomes altered when exposed to CO. The altered state more strongly holds oxygen, and won’t release it to the cells that need it; CO disrupts what is called blood “cooperativity.”

    Many home CO meters have a strip containing an artificial haeme molecule mixture that mimics human blood – the color of the strip alters at specific time * concentrations of CO. So, for example, pursuant to that curve, 220 minutes @ 100 ppm, 45 minutes @ 300 ppm, and 15 minutes at 800 ppm, are all equivalent COHb 20% saturation points.

    Although they are a great idea for homes (I have two such monitors in my home), they are virtually useless for scientific indoor air investigations.

    DavidR mentioned the UL 2034 standard. If you read up on that standard, you will see an example of the set-point disassociation curves to which he was alluding.

    Cheers!
    Caoimhín P. Connell
    Forensic Industrial Hygienist
    Forensic Industrial Hygiene

    (The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

    AMDG

    Last edited by Caoimhín P. Connell; 11-23-2008 at 03:09 PM. Reason: Changed "...COHb 10% saturation..." to "...COHb 20% saturation..."

  22. #22
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    All the techinical and scientific information is very educational.
    The simple fact that a CO detector saved my wife and me is a no-brainer.
    The CO detector in our motorhome is located 6 inches above the floor.
    The pilot light on the cook top went out during the night...and we were awakened by the shrill sound of the detector.
    We make sure the gas is OFF to the stove.


  23. #23
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by RANDY NICHOLAS View Post
    The simple fact that a CO detector saved my wife and me is a no-brainer.
    The CO detector in our motorhome is located 6 inches above the floor.
    The pilot light on the cook top went out during the night...and we were awakened by the shrill sound of the detector.
    We make sure the gas is OFF to the stove.
    Randy,

    That was not the CO detector which went off down low, that was the gas detector.

    Jerry Peck, Construction / Litigation Consultant
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    www.AskCodeMan.com

  24. #24
    Martin Grant's Avatar
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    I remember reading about a European code which required the CO detector at nominal head level of 5 - 6 feet. Makes sense for an essentially neutrally buoyant gas.


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by Jerry Peck View Post
    Randy,

    That was not the CO detector which went off down low, that was the gas detector.
    Jerry, that brings up a good point. I've not looked in the past, but are there relatively inexpensive gas detectors that can be purchased and installed similarly to CO detectors? I mean for homeowners.

    Bruce

    Bruce Thompson, Lic. #9199
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  26. #26

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Good morning, Martin:

    One of my CO detectors is located about four inches off the ground – but that happens to be at the top of a flight of stairs which at as a thermal bypass, the bottom of which is where one of our wood burning stoves is located (our primary source of heat).

    So, the location of the meter is simultaneously at ground level (at the bottom of the second floor), and at ceiling level (at the top of the ground floor).

    CO will move along pressure differentials – that’s it. The most important point in location selection is 1) Occupancy considerations and then second 2) Anticipated air flow patterns.

    Bruce -

    Good question. However the problem would be with regard to determing the end point. For example, is the end point explosion to toxic properties? A perfect case in point would in fact be CO - which is an explosive gas.

    There are infrared gas analyzers for distiguishing various gas species, but I have never seen anything for home owner. Usually, we just rely on the mercaptans that are introduced into gas to make it smell bad.

    Cheers!
    Caoimhín P. Connell
    Forensic Industrial Hygienist
    Forensic Industrial Hygiene

    (The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

    AMDG


  27. #27
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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Quote Originally Posted by JB Thompson View Post
    are there relatively inexpensive gas detectors that can be purchased and installed similarly to CO detectors? I mean for homeowners.
    I've not looked either, but the ones in our various RVs were all powered by 12 volts.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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    Default Re: Carbon Monoxide detector 1 ft. above floor

    The point about gas detectors brings up a good point talking about stratification.
    It has been well documented of propane's propensity to move towards the floor of a structure.

    Would love to hear Caoimhín's thoughts on this and on how Fick's laws of diffusion would apply here also.

    Thanks in advance.

    Measured Performance more than just a buzzword

  29. #29

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Good morning, Gents –

    I hope all had a bountiful Thanksgiving in whatever part of this glorious country you happen to be in.

    Hello DavidR:

    I’ve written elsewhere on the issues (mostly limitations) posed by diffusion barriers on all kinds of passive monitors whether they are CO, radon, or POVMs (passive organic vapor monitors). Essentially, in a nut shell, any monitor that that has a diffusion barrier between the ambient air and the sensor, and which has a sensor (or reaction chamber) wherein the analyte of interest decays or is altered, will suffer response time limitations that are based on the diffusion coefficient for that gas.

    We particularly see large deviations in “real-time” monitoring with radon monitors and POVMs (which is why I never use POVMs, although they have utility in some applications). I presume that my investigatory CO monitor has a diffusion barrier but my calibraitons show that the respnse time is not hindered.

    Otherwise, for the most part, because of the fact that air movement overwhelms any diffusion issues, Fick’s Law isn’t really applicable for a fee mass of analyte within another mass (such as an evolving mass of CO in room air).

    However, in my scenario above, wherein I have used a sealed chamber, the toluene will mix with the air in the absence of any “mechanical mixing” precisely because of Fick’s (and the concept of “mean free path.”) We usually don’t evoke Fick’s in open compartment models like that, but instead we use the ideal gas law, and Daton’s Law of partial pressures.

    If an home-style CO monitor had a diffusion barrier, I would not expect it to suffer any greater limitation that it already has, and this is due to the slow respnse time inherent in the detection system anyway.

    Cheers!
    Caoimhín P. Connell
    Forensic Industrial Hygienist
    Forensic Industrial Hygiene

    (The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

    AMDG


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    Default Re: Carbon Monoxide detector 1 ft. above floor

    Hey, wow there's some crazy facts and figures makin for some interesting reading on this thread! I've been professional firefighter past 23 yrs. and we've done home invasions, oops, inspections, for the past 15 anyways. Yes there's great decently priced natural gas detectors out there for residential use. Follow directions. We like to see a smoke detector on every level and at least ONE CO detector and that should be somewhere outside the main sleeping area. But the more the merrier. sp? The CO detectors don't seem to last more than five years, generally they go off, we get called, use both our high-tech meters and generally find defective meter. Point being if they give bad readings at 5 yrs. would they work if necessary. Replace them at least every 5 yrs. to be safe I think.


  31. #31
    Michael Greenwalt's Avatar
    Michael Greenwalt Guest

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Soooo..........................the detector goes where? Keeping in mind I address it on the go with the client so the calculations are umm,,,,err,,,,,,beyond my capability. Of course if I had time I could do all the calculations (yea right!)

    and who is this "Ficks" guy, he sounds controversial

    Thanks for the posts, good information


  32. #32
    Michael Greenwalt's Avatar
    Michael Greenwalt Guest

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Soooo.......................... oops, deleted

    Last edited by Michael Greenwalt; 12-31-2008 at 09:51 AM. Reason: redundant, rhetorical, not needed, bad hair day

  33. #33
    Kirk Hersee's Avatar
    Kirk Hersee Guest

    Default Re: Carbon Monoxide detector 1 ft. above floor

    Thanks for the great thread. I never needed to know why CO detectors had to be located in certain areas of the home (per insurance companies), just that they were there. I always thought because the source (usually) came from the basement where a furnace would be, that the CO would reach a lower level first; such as an outlet in the hall outside the basement door area. Therefore, if you were sleeping in your bed at an approximate 3' height, you'd be sooner warned. I have been enlightened by this information. Although, I'm no scientist, I have to say that Caoimhín's posts were rather interesting. Thanks again!


  34. #34
    Join Date
    Mar 2008
    Location
    southern ontario
    Posts
    130

    Default Re: Carbon Monoxide detector 1 ft. above floor

    I'd say detector goes outside sleeping areas wherever they are, if bedrooms down and up then put one down and one up. Weather their 3 ft. off grnd. or on ceiling isn't too important but it is important not to have them in corner, weather that corner is where two walls meet or wall and ceiling meet or floor and ceiling. You can get dead air space there.


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