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So close it's not funny, this time CO detectors really saved lives.

GBartGBart Member Posts: 678
In Thornton, New Hampshire six people went to the hospital due to CO poisoning, they woke to the alarm and then......


  • GBartGBart Member Posts: 678
    "Authorities said that at around 5 a.m. a resident awoke to the sound of the CO alarm, but was quickly overcome by the gas luckily several people were able to quickly call 911.

    A state trooper was the first on scene and found two victims right by the front door. The trooper acted quickly opening all the doors and windows to ventilate the home which had deadly levels of carbon monoxide."

    Two men, a woman and three children all within seconds of hearing the alarm start to go down, sounds like a catastrophic failure of some sort but I have not been able to find a follow up story as to the actual cause.

  • NY_RobNY_Rob Member Posts: 1,308
    Some more info on it here....

    After residents were evacuated the FD found "pockets" of CO as high as 700ppm inside the home.
  • GBartGBart Member Posts: 678
    edited April 2018
    Yeah, bear in mind those fire dept tests were done after the state police opened the doors and windows, and we don't know how long after, @700ppm you have headache, nausea, and dizziness after 45 minutes; collapse and unconsciousness after 1 hour of exposure, death within 2-3 hours.

    My guess is around the time they woke up from the alarm and tried to make the door they were in the 10,000ppm range which can give immediate unconsciousness and death within minutes.

    The trooper is actually very lucky, he could have gone down as well, it's happened.
  • captaincocaptainco Member Posts: 406
    Saved their lives but it would have been much better if it had gone off before they were exposed to life threatening levels. This time they just conscience enough to make a call. What if they went off before you got sick? Then you would be wasting a call to 911 or at least that was the reasoning for the higher levels of alarms today.
  • Jean-David BeyerJean-David Beyer Member Posts: 2,565
    When the power went off for 6 1/2 days after storm Sandy, my heat was off too. My house is quite well insulated, but the temperature got below 60F after a few days. I lit six or eight fat candles and closed the bedroom door. They actually raised the room temperature by about 2F after an hour or so, but my fancy Aeromedix COexperts CO detector went off from the candles at 10ppm.

    I did not know that candles produced significant levels of CO (CO2 I could expect). I do not suppose the gasoline powered generator from the house across the street generated enough CO to cross the street, infiltrate my house, and set off the detector. In any case, I blew out several of the candles and the CO detector quieted down.
  • GBartGBart Member Posts: 678
    edited April 2018
    Most CO detectors are cumulative, they can go off after long periods of low levels or a sudden spike, without an accurate digital read out that displays current levels you really have no idea what you have going on.

    That's why when we respond to most alarms we find nothing.

    Anything that has a yellow flame like a candle generally has high CO, not always but usually, especially LP or NG and all of our fuel burners should have a suspended flame that touches nothing.
  • captaincocaptainco Member Posts: 406
    Not true. UL testing does not allow Alarms to go off below 30 ppm whatsoever or at that levels for at least 30 days continuous.

    Also high spikes are tested and will fail UL testing.

    Digitals can't read until they hit 30 ppm which is also stupid. CO between 5 ppm and 30 ppm can have major affects on the young and the old, persons with heart problems or respiratory problems.

    Only First Alert with the biometric (spelling) is cumulative but still restricted to the levels above.

    When I investigate CO issues my concern is not what is in the air when get there other than personal safety, but eliminating all the sources that could have produced it intermittently and make sure there aren't any. Too many are concerned what is there at the moment versus what might have been there before the place was ventilated versus what could have caused it.
  • Mad Dog_2Mad Dog_2 Member Posts: 3,455
    Captain CO has spoken! Mad Dog
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • GBartGBart Member Posts: 678
    edited April 2018

    CO detectors are cumulative.

    In fact CO IS a cumulative poison.

    When I say detectors I refer to battery powered cheapos, they are cumulative and will go off after long periods of low exposure, professional hard wired alarms especially with a digital read out are not cumulative but you need to check the product info to be absolutely sure. Typically they will list it as a purge and reset model. They purge themselves of acquired low levels of CO and begin again at 0ppm.
  • SuperTechSuperTech Member Posts: 549
    I always encourage my customers to have several low level CO detectors installed. Powered with battery backup is preferred. And I try to remind them to replace detectors when they get older.

    CO safety is my number one priority when I service a heating system. I try to learn everything I can to make the systems safe.
  • captaincocaptainco Member Posts: 406
    Not sure what you mean by cumulative? If there is 30 ppm in a room for 1 hour or 12 hours the highest the alarm will register is 30 ppm.

    If a person is in a room at 30 ppm for 1 hour or 12 hours the most they have in their blood is 30 ppm. The damage over time is cumulative but only at the maximum levels they are exposed.
  • GBartGBart Member Posts: 678
    Some alarms do not give a read out, they accumulate over time. The purchaser needs to check this because you want an alarm that will go off when required and with a current ppm read out.

    You could have smokers in a house or a gas stove or they start their car in the garage every day and after a while some alarms will go off, generally the cheapos because they have been exposed to low levels over a long period of time.
  • SuperTechSuperTech Member Posts: 549
    @GBart I agree. I always recommend a low level CO detector unless the home is occupied by a smoker or if they do a lot of cooking and don't have an exhaust hood
  • LeonardLeonard Member Posts: 516
    edited April 2018
    Just trying to learn. Do some residential CO detector models after seeing some constant level of CO (say 30 ppm) for say ~ a month automatically re-zero themselves and call that level the new 0 ppm baseline from which they measure from??
  • captaincocaptainco Member Posts: 406
    They don't zero themselves but they will clear the memory of the highest reading in the past 30 days. They do not zero or re-calibrate..
  • captaincocaptainco Member Posts: 406
    We tested smoke filled bars and rarely are above 15 ppm. Unless a smoker is sitting right under the alarm it is doubtful they can set it off.
  • GBartGBart Member Posts: 678
    For instance one manufacturer states: What causes CO detector nuisance alarms?
    Pollution and atmospheric conditions in some areas cause low levels of CO to be present for long periods of time. In fact, these
    "background" conditions may increase the COHb level to over 10%, causing CO detectors to alarm even though conditions inside the home are not truly hazardous.

    Another states: Today carbon monoxide alarms use electronic circuits usually involving a small microprocessor to calculate when to initiate alarm signals based on exposures to hazardous CO concentration and time. An accumulation of CO over time must be calculated based on a formula similar to the Coburn equation or a simple look up table. The graph and the equation showing the relationship between CO concentrations and exposure times versus percent carboxyhemoglobin (%COHb) are given in the Underwriters Laboratories (UL) 2034 CARBON MONOXIDE ALARM standard, which costs over $300 to purchase.

    Under certain conditions for short term exposures to elevated levels of CO, i.e., the %COHb levels are below the saturation levels: one may assume there is a linear relationship of CO concentration uptake. This assumption does not hold for low levels over long time periods and it is best to use the full Coburn-Forster-Kane (CFK) equation Please Click to see the complete CFK equation( ).

    One simplification of CFK equation that has been used is the following:

    %COHb= (3.317 x 10-5) X (CO ppm) X 1.036 X (RV) X (t)


    CO ppm = carbon monoxide concentration in parts per million (ppm)

    RV (Respiratory Volume) = volume of air breathed in liters per minute (lpm) (Typical adult is about 5.2 lpm)

    t = exposure time in minutes

    This formula was taken from Stewart, R.D., Peterson, J.E., Fisher, T.N., Hosko, M.J., Baretta, E.D., Dodd, H.C., Herrmann, A.A., "Experimental Human Exposure to High Concentrations of Carbon Monoxide", Arch. Environ. Health, 26, 1-7, 1973.
  • captaincocaptainco Member Posts: 406
    Unfortunately none of the CO exposure lengths take into account body weight, activity rate or lung capacity. Most are based on middle aged healthy adults at rest.

    Nitrous oxides, methylene and ethylene chlorides, hydrogen sulfides, ammonia, natural gas (even human produced), propane and acetylene can all cause alarms to go off. Of course, only human produced gas is harmless except to the olfactory senses.
  • Jean-David BeyerJean-David Beyer Member Posts: 2,565
    I have the 2014 version of this model smoke detector in my bedroom, and the cheaper Big-Box-Store UL-Approved ones on each floor of my house.
  • Mad Dog_2Mad Dog_2 Member Posts: 3,455
    I think the National Comfort Institute Detectors are the best around for the wall and the BW CLIP
    brand for carrying around. They respond sooooo
    Quickly. Mad Dog
    To learn more about this professional, click here to visit their ad in Find A Contractor.
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