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  • ion vs.photo - is the ion flawed?

    I am curious to know how many people on Fire dept.s are aware of the following. If people are not aware - why not!

    Please provide feedback. Thanks.

    ISSUE ONE: ION DETECTORS GO OF TOO LATE IN SMOLDERING STARTED FIRES

    According to the USFA approximately 40% (1,200 people per year) died when detector operates.

    Now gop to the following website (htp://smokealarm.nist.gov/HSAT.pdf). It is a report done by the National Institute of Standrads and Technology that summarizes the results of some fire testing they did.

    On Page 75-76 (101-102 on the internet) it shows a diagram of the 2 story house they used. On page 243 (269 on the internet) it shows the results for that house. I have summarized them below. Note that for the smoldering fire started in the Living Room the Ionization detector is providing at best 16 seconds warning and at worst ig going off 54 seconds after it is too late. (Sound familiar to last year fire.) The Photoelectric detector in the same scenarios is responding 40-55 minutes earlier!

    ISUE TWO: THE % OF PEOPLE DYING WHEN THE SMOKE DETCTOR OPERATES HAS BEEN INCREASING SINCE THE LATE 80'S.

    . Here is a summary of statistics from previous USFA Reports titled “Fire in the U.S.” Increase in fatal fires with working detectors – 1988 (9%), 1994 (19%), 1996 (21%), 1998 (29%), 2001 (39%). While there will always be a certain percentage of people who cannot be saved by smoke detectors, e.g. the handicapped, those intimate with the fire etc., there is no reason to believe that the number of those people quadrupled between 1988 and 2001. In addition, while the number of fires with working detectors increase approximately in proportion to the increase in the number of detectors installed, the increase in the % of fatal fires with working detectors far exceeds it.


    In my opinion the best explanation is that starting in the late 80’s, Underwriters Labs, in an attempt to reduce nuisance alarms, forced the manufacturers to make less sensitive ionization detectors. Shortly after this change UL modified the smoldering test in UL217, the UL Smoke Detector Standard, in ways that made it much easier for the ionization detector to pass. The gradual introduction of these desensitized ionization detectors into American homes is the most reasonable explanation for the increase in fire deaths in cases where the detector operated. As a consequence this unrecognized flaw could be responsible for hundreds of deaths per year.



    ISSUE THREE: ION DETECTOR ARE FAR MORE SUSCEPTIBLE TO NUISANCE ALARMS. T (20% (approx 600 people per year) died bacuse detector disable.)

    In the study that took place in the Native American Community14 there were not a lot of photoelectric detectors used. To quote from the study,
    "There were only three photoelectric detectors in our survey, none of which had nuisance alarms. One trailer had two of these detectors, each of which was paired with an ionization detector that was installed within 6 inches of it. Both of the ionization detectors sounded cooking nuisance alarms. In another home, the photoelectric detector was located 6 feet closer to the stove than an ionization detector, which had frequent alarms from cooking."
    As a consequence of these types of observations the researchers concluded that,
    ... We favor photoelectric detectors to reduce rates of nuisance alarms from cooking and to provide optimal protection from cigarette related fires. Electrical detectors with battery back-up are the detectors of choice, except in communities such as remote villages in Alaska, where alternating current is non-existent or unreliable. If ionization detectors are installed, they should be located at least 20 feet, and preferably 25 feet, from stoves and at least 10 feet from bathroom doors if possible."

    This is a complicated story. I do not want to send a message that smoke detectors do not work. Even ion are far better than nothing, But I do beleive that one type, photo or combinations, is far superior to the most common type, ion.

    •Photolelectric detectors might reduce by 1/2 the # of people dying in fires, when the detector works. (This would be a 20% reduction.)
    •Photelectric detectors might reduce the number of disabled detectors due to nuisance alarms. (Assume problem reduced by 1/2 - 10% reduction)
    •It seems reasonable to assume that switching from ionization to photoelectric technology could save 960 lives (.30 * 3,200) per year!

    This number could be higher, if # of fatalities that occur when no smoke detector present is over-estimated. (Many Chief's assume that if occupants died then the smoke detector wasn't there - go
    marshal is online now Edit/Delete Message

  • #2
    Before this thread goes any further...

    Please raise your right hand and swear or affirm you are not affiliated with Master Guard or another snake oil heat detector sales organization.

    While ion smoke detectors have some limitations, the wording used just raises spidey sense hairs on the back of my neck we have Master Guard trying to raise Fear, Uncertainity, and Doubt like they did in the late 1990s in the online forums. That took quite a bit of effort to drive them away...they're still around, at least we don't have to put up with their information spin & manipulation campaigns.

    (For those unfamiliar with Master Guard, they sell a wind-up mechanical heat detector as the "solution" for ion smoke detectors...at $200 to 300 a pop. For the cost of a Master Guard solution of independent mechanical and standalone photoelectric detectors...you could install a wired alarm system with both ion and photo detectors and central station notification. And they like to sell these using "firefighter" salesmen combined with hard-sell scare tactics. And they've gotten their hands slapped more than once by the Fair Trade Commission and similiar organizations.)

    If this isn't a backdoor Fear, Uncertainity, Doubt campaign I apologize in advance -- just be aware of these concerns from the past.

    Generally the fastest notification to all types of fires come from the combination of ion (good at hot, fast developing fires) and photo (good for cool, smouldering fires). Either alone will give OK notification...together they work best.

    Comment


    • #3
      I do not work for any manufacturer

      I do not work for anyone, unlike most of the reps on the nfpa 72 committee.

      I would appreciate it if people stuck to the facts.

      What do they think of the results of the NIST testing?

      Why do they think that 40% of the people who die in fires die when the detector operates?

      Why has that number doubled since UL allow3d less sensitive detectors to be sold?

      Thanks.

      Comment


      • #4
        Personally... I think the reason for fire deaths in homes and apartment/condo buildings with smoke detectors of either type are...

        1. People ignore the detectors when they go off (the cry wolf syndrome).

        2. People disable the detectors because they are "a nuisance" (the stupidity factor).
        ‎"The education of a firefighter and the continued education of a firefighter is what makes "real" firefighters. Continuous skill development is the core of progressive firefighting. We learn by doing and doing it again and again, both on the training ground and the fireground."
        Lt. Ray McCormack, FDNY

        Comment


        • #5
          ion vs, photo

          I agree that some people ignore them but I have been to too many fires were one of the survivors testified that they woke up right when the smoke detector operated but the house was lready filled with smoke.

          THIS IS WHAT THE NIST TESTING SHOWS. I WOULD APPRECIATE IT IF PEOPLE WENT TO THE PAGES ON THIS REPORT THAT I SUGGEST.

          Plus that would not explain why the % has increased so much since UL allowed them to sell less sensitive detectors.

          It appears that switching to photo could substantially reduce the number of disabled detectors. Even NFPA 72 requires a photo or an ionization with a "silence" button near kitchens. Massachusetts has required photlectric near kitchens for about 10 years.

          Comment


          • #6
            I would appreciate it if people stuck to the facts.

            Anything not factual in my post other than the question?

            From the NIST report you listed, executive summary:

            Smoke alarms of either type installed on every level generally provided the necessary escape
            time for different fire types and locations.
            Adding smoke alarms in bedrooms increased the
            escape time provided, especially for smoldering fires. These tests quantified an increased escape
            time for fires starting in the bedroom.
            The results obtained were similar to those of the earlier work. Both common residential smoke
            alarm technologies (ionization and photoelectric) provided positive escape times in most fire
            scenarios with the ionization type reacting earlier to flaming fires and the photoelectric type
            reacting earlier to smoldering fires.
            The main difference from the earlier work is that the amount
            of escape time provided is consistently less. For example, average times to untenable conditions
            for flaming tests was 3 min compared to 17 min in the prior work. While some of this difference
            may be attributed to the tenability criteria used in the current study, it is also clear that fire
            growth in the current tests are significantly faster than in the earlier tests. For flaming fire, time
            to alarm activation and measurement of elevated temperatures in the room of fire origin support
            this faster fire growth observation.
            However, the smoldering fire scenarios are very difficult to
            reproduce experimentally and tenability times in the present study have an uncertainty (based
            upon one standard deviation) which overlaps the uncertainty from the 1975 study. Therefore,
            caution should be exhibited in drawing conclusions based upon comparisons of smoldering
            tenability times between the two studies. It is important to note that while both the 1975 study
            and the current study attempted to use a representative sample of available and important
            furnishings, each study included only a small fraction of those available in the marketplace.
            Still, this study is consistent with other recent studies of furniture and mattresses, even though
            there may be significant differences in the burning behavior between items of furniture.


            I'm not really sure how your point #1, that ion detectors go off too late in smouldering fires, is supported by the report when that reports very own conclusions is that both types normally perform acceptably, with a slight advantage to one or the other depending on the fire.

            The HUGE part of the report to emphasize is the dramatic increase in fire growth and reduction in escape times since the 1970s research. It's now a 3 minute time v. 17 minutes in 1975. Most of that due to growth in hot, flaming fires (hmmm, the ones ion detectors do better on...).

            That fact also makes me wonder if it's not a detector problem -- the escape time has dropped so dramatically does that fact, rather than the timeliness of the warning, account for the 40% die when the detectors sound -- they just don't have the time to escape from the flaming fires; and one would think the products of combustion of the smouldering fires has also increased in it's lethality over the past 30 years. For that matter, even with the hot flaming fires that smoke is banking down much, much faster than 30 years ago similiarily catching people and causing confusion or difficulty breathing much faster...resulting in fewer escapes. Are there reports to quantify where the victims are being found? Can we figure out if they're getting trapped by the fire while attempting to escape? Are they dying still asleep (passed out...)?

            The first line of your post asked the question:

            If people are not aware - why not!

            Well, read my original post again.

            If firefighters who have been online for 5+ years are either unaware...or rather, very skeptical...of such claims it's because the subject has been so heavily tainted by charlatans looking to make a lot of bucks by taking reports of the "ineffectiveness" of ion detectors and selling an overpriced, wrong solution for the issue.

            Unfortunately for people genuinely concerned on the issue, that is a condition you need to overcome.
            Last edited by Dalmatian190; 09-03-2006, 05:03 PM.

            Comment


            • #7
              ion & nist

              Fisrt,

              Thanks for taking the time to go to the NIST Report. I think this is a really important issue so I appreciate the time you tooK.

              My coments are in capital letters.

              I would appreciate it if people stuck to the facts.

              Anything not factual in my post other than the question?

              From the NIST report you listed, executive summary:

              Smoke alarms of either type installed on every level generally provided the necessary escape
              time for different fire types and locations.

              THIS IS TECHNICLLY TRUE. BUT THE DATA STILL SEEMS TO SHOW THAT THE MOST COMMON DETECTOR. I.E. ION, GOES OFF TOO LATE IN THE MOST COMMON FATAL SCENARIO, I.E. SMOLDERING STARTED FIRES IN THE LIVING ROOM. I AM NOT SAYING THEY DO NOT OPERATE IN TIME FOR SOME SCENARIOS, BUT I THINK IT IS IMPORTANT TO NOTE THAT THEY DO NOT GO OFF IN TIME IN SOME VERY COMON SCENARIOS



              Adding smoke alarms in bedrooms increased the
              escape time provided, especially for smoldering fires. These tests quantified an increased escape
              time for fires starting in the bedroom.
              The results obtained were similar to those of the earlier work. Both common residential smoke
              alarm technologies (ionization and photoelectric) provided positive escape times in most fire
              scenarios with the ionization type reacting earlier to flaming fires and the photoelectric type
              reacting earlier to smoldering fires.

              ACTUALLY, THE EARLIER REPORT, I.E. INDIANA DUNES 9THE MID 70'S)INDICATED THAT THE ION DID GO OFF IN TIME, SO IN THAT SENSE THE RESULTS ARE DIFFERENT.

              THESE TEST SHOW THE ION GOING OFF 40-50 SECONDS AFTER IT IS TOOL LATE TO GET OUT OF THE HOUSE. SO THE TIME TO ESCAPE IS IRRELEVAMT. EVEN IF PEOPLE WAKE UP IMMEDIATELY IT IS TOO LATE.

              The main difference from the earlier work is that the amount
              of escape time provided is consistently less. For example, average times to untenable conditions
              for flaming tests was 3 min compared to 17 min in the prior work.

              MY CONCERN IS WITH THE CHANGE IN THE SMOLDERING TEST RESULTS, SO THE FACT THAT THE FLAMING TESTS ARE GROWING FASTER IS IRRELEVANT TO MY POINT.

              IN ADDITION, I HAVE CJECKED THE MID 70'S INDIANA DUNES IGNITION METHOD (THESE REPORTS ARE AVAILABLE AT THE NIST WEB SITE.) AND IT LOOKS LIKE A LOT OF THE TIME DELAY IN FIRE GROWTH WAS DUE TO THE IGNITION METHODS. SOMETIMES IT WOULD TAKE 5-8 MINUTES FOR THE FURNITURE TO ACTUALLY IGNITE,

              THIS WOULD STIL MEAN THAT FIRES WERE GROWING FASTER BUT THAT WOULD BE DUE TO MATERIAL CHANGES, PROBABLY NATURAL TO SYNTHETIC. BUT DATA I WAS ABLE TO GET FROM THE NFPA SEEMS TO INDICATE THAT MOST OF THE CHANGEOVER OCCURRED BY THE LATE 80'S. AS A CONSEQUENCE IT CANNOT EXPLAIN THE INCREASE IN FATALITIES SINCE THE LATE 80'S.

              While some of this difference
              may be attributed to the tenability criteria used in the current study, it is also clear that fire

              ACTUALLY THE TENABILITY CRITERIA ARE ESSENTIALLY THE SAME.

              growth in the current tests are significantly faster than in the earlier tests.

              ONLY FOR THE FLAMING TESTS.

              For flaming fire, time
              to alarm activation and measurement of elevated temperatures in the room of fire origin support
              this faster fire growth observation. However, the smoldering fire scenarios are very difficult to
              reproduce experimentally and tenability times in the present study have an uncertainty (based
              upon one standard deviation) which overlaps the uncertainty from the 1975 study. Therefore,
              caution should be exhibited in drawing conclusions based upon comparisons of smoldering
              tenability times between the two studies.

              THIS IS ESENTAILLY SAYING THAT THE SMOLDERING FIRES ARE GROWING AT APPROXIMATELY THE SAME RATE.

              It is important to note that while both the 1975 study
              and the current study attempted to use a representative sample of available and important
              furnishings, each study included only a small fraction of those available in the marketplace.
              Still, this study is consistent with other recent studies of furniture and mattresses, even though
              there may be significant differences in the burning behavior between items of furniture.

              I'm not really sure how your point #1, that ion detectors go off too late in smouldering fires, is supported by the report when that reports very own conclusions is that both types normally perform acceptably, with a slight advantage to one or the other depending on the fire.

              The HUGE part of the report to emphasize is the dramatic increase in fire growth and reduction in escape times since the 1970s research. It's now a 3 minute time v. 17 minutes in 1975. Most of that due to growth in hot, flaming fires (hmmm, the ones ion detectors do better on...).

              That fact also makes me wonder if it's not a detector problem -- the escape time has dropped so dramatically does that fact, rather than the timeliness of the warning, account for the 40% die when the detectors sound -- they just don't have the time to escape from the flaming fires; and one would think the products of combustion of the smouldering fires has also increased in it's lethality over the past 30 years. For that matter, even with the hot flaming fires that smoke is banking down much, much faster than 30 years ago similiarily catching people and causing confusion or difficulty breathing much faster...resulting in fewer escapes. Are there reports to quantify where the victims are being found? Can we figure out if they're getting trapped by the fire while attempting to escape? Are they dying still asleep (passed out...)?

              The first line of your post asked the question:

              If people are not aware - why not!

              Well, read my original post again.

              If firefighters who have been online for 5+ years are either unaware...or rather, very skeptical...of such claims it's because the subject has been so heavily tainted by charlatans looking to make a lot of bucks by taking reports of the "ineffectiveness" of ion detectors and selling an overpriced, wrong solution for the issue.

              I AGREE THAT A LOT OF MY PROBLEM WITH TRYING TO GET A RATIONAL DISCUSSION ON THIS ISSUE IS THAT MANY PEOPLE WHO HAVE RAISED THIS IN THE PAST HAVE DONE SO IN AN IRRESPONSIBLE MANNER. I HAVE BEEN ABLE TO MAKE SOME PROGRESS IN AUSTRALIA. GO TO http://www.afac.com.au/awsv2/publica...nformation.htm

              Unfortunately for people genuinely concerned on the issue, that is a condition you need to overcome.

              ONCE AGAIN THANKS FOR TAKING THE TIME TO RESPOND.

              Comment

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