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    Default Hydrogen cyanide monitoring at fires

    Hi all, just curious if anyone carries hydrogen cyanide detectors for use during overhaul at fires. I handle all our air monitoring equipment and was recently approached by one of our ACs to look into monitoring for this, due to some of the firefighter cyanide poisoning issues brought to light in the last couple years.

    We carry 4 gas detectors on all our front line rigs and BC rigs (O2, CO, LEL, and H2S). I was thinking of maybe just pulling the H2S sensor on the BC air monitors and adding in the hydrogen cyanide sensors on those, since one of those is always on every fire.

    Anyone else monitor for this at fires? Thanks, Kevin
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    I'd be interested to know what the accuracy is of a 4 gas meter operating in smoke or overhaul conditions. The issue with what gases are present, at what level could skew the meter's reading. Just like a low oxygen concentration takes the CO detector out on most meters due to the way the meter reads the gas. I know Providence FD was really hot on the HCN issue, talk to someone there they've always been an excellent resource.

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    A couple of questions come to mind from your post. First, can you just pull the H2S sensor and put in another without changing the software for the meter? I honestly don't know how plug-and-play meters may be.

    Would it be cheaper to just buy a HCN meter? You got me curious and did some looking. I found one for about $385 (sensors for that particular model were $285). I'm sure there are others out there, I didn't do an all-out search.

    Somewhere I have read where the levels of HCN will decrease proportionally with the CO levels. Once your CO levels reach acceptable levels (we use <20 ppm), the HCN should be at a safe level. While I don't remember where it is (I'm sure it's online somewhere), perhaps someone else here does and will post it. I'll do some looking myself and see if I can find it.

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    Quote Originally Posted by RFDACM02 View Post
    I'd be interested to know what the accuracy is of a 4 gas meter operating in smoke or overhaul conditions.
    Thanks for the feedback. If oxygen levels are off, the LEL readings may be off, but I believe the other gases should be correct as they don't read relative the oxygen level (according to Industrial Scientific anyway, and that's who we use). Either way, our standard is if O2 is off, don't count on any readings being accurate.

    Quote Originally Posted by Catch22 View Post
    A couple of questions come to mind from your post. First, can you just pull the H2S sensor and put in another without changing the software for the meter? I honestly don't know how plug-and-play meters may be.
    On ours you can, don't know about other brands. It will recognize the sensor. However, have to have the cal gas for the new sensor.

    Quote Originally Posted by Catch22 View Post
    Would it be cheaper to just buy a HCN meter? You got me curious and did some looking. I found one for about $385 (sensors for that particular model were $285). I'm sure there are others out there, I didn't do an all-out search.
    Sensors for our current monitors are cheaper than buying another monitor, but that hasn't been ruled out.

    Quote Originally Posted by Catch22 View Post
    Somewhere I have read where the levels of HCN will decrease proportionally with the CO levels. Once your CO levels reach acceptable levels (we use <20 ppm), the HCN should be at a safe level. While I don't remember where it is (I'm sure it's online somewhere), perhaps someone else here does and will post it. I'll do some looking myself and see if I can find it.
    Interesting, have to look to see if I can track down that info somewhere and how they correlate. IDLH for HCN is 50ppm vs. 1500ppm for CO. Plus, we can drop a pack below 100ppm CO, so don't know what HCN levels may still be present.

    Thanks for the input, look forward to any other info people can provide. Kevin
    Last edited by fyrmnk; 02-14-2008 at 03:04 PM.
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    Default What about the other hazardous gases

    If you find a method to accurately identify the level of cyanide in the post fire environment I wonder if you are considering all of the other chemical compounds floating around.

    I think there are several hundred gases that are confirmed to exist in post-fire environments. Benzene, acrolien (sp), PAH's, etc., etc. How are you monitoring for all of these chemicals?

    This does not cover the particulates. Are you monitoring for asbestos?

    What is the acceptable level of risk in a post-fire, non-life threatening environment? I went to two LODD cancer funerals last week. Perhaps we should not be breathing that S$#t at all.

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    We also use Industrial Scientific and my understand is that all the sensors us the "Wheat-stonebridge" (???) sample burning method of detection and measure? As it has been explained to me, once the oxygen level is less than 19% all bets are off as you can no longer sustain "flame" to accurately burn the sample. I think you hit it on the head that anytime O2 is low its best to not trust the reading, in our case we'd use a PID or Drager tube s to measure further if it was necessary.

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    Quote Originally Posted by RFDACM02 View Post
    We also use Industrial Scientific and my understand is that all the sensors us the "Wheat-stonebridge" (???) sample burning method of detection and measure? As it has been explained to me, once the oxygen level is less than 19% all bets are off as you can no longer sustain "flame" to accurately burn the sample. I think you hit it on the head that anytime O2 is low its best to not trust the reading, in our case we'd use a PID or Drager tube s to measure further if it was necessary.
    Yeah, they use that for the combustible gas sensor which is why O2 levels high or low can give you high or low LEL readings. However the other gases are done with electromechanical sensors that don't rely on the O2 level (at least as explained to me and the way I read it on their site).

    This should allow accurate toxic gas level readings regardless of O2 level if I understand it correctly. Kevin

    EDIT:

    Here's a little info on both types for anyone bored enough to read it:
    http://www.indsci.com/support/tech/tech.aspx?ID=1548
    http://www.indsci.com/support/tech/tech.aspx?ID=1552
    Last edited by fyrmnk; 02-14-2008 at 05:33 PM.
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    My department borders Providence and as far as I can tell, they send more companies and safety officers to fires but judging by the number of guys you repeatedly see in heavy smoke conditions with no mask on, nothing has changed.

    We carry MultiRae detectors and changed out one of the sensors and put in the HCN. It was done at the factory as far as I know. Our safety officer either takes it inside after the fire is knocked down or he gives it to an officer to take in. We are not to remove our masks until we are told it is at a safe level.

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    Adam,we've got an "in" at Providence,maybe we should query the "honorable"Pat O'connor.After all he's one of your's.It's a serious enough issue that we're taking a long hard look at how we do monitoring. T.C.

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    Quote Originally Posted by fyrmnk View Post
    Hi all, just curious if anyone carries hydrogen cyanide detectors for use during overhaul at fires. I handle all our air monitoring equipment and was recently approached by one of our ACs to look into monitoring for this, due to some of the firefighter cyanide poisoning issues brought to light in the last couple years.

    We carry 4 gas detectors on all our front line rigs and BC rigs (O2, CO, LEL, and H2S). I was thinking of maybe just pulling the H2S sensor on the BC air monitors and adding in the hydrogen cyanide sensors on those, since one of those is always on every fire.

    Anyone else monitor for this at fires? Thanks, Kevin
    I had the same thought. But, I am trying to find the life exptacny of the sensor. Some sensors last a year, some 5, some 6 months. We do not get a lot of fires and I think that spending this for something that will expire prior to use will be hard to sell. One of the guys that I know got a single gas from Rae, but has yet to try it out.
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    Scott has the Scout model portable gas detector and it can go up to 5 gas detection. ONLY the standered combustable gas sensor not the duel range sensor reads the O2 sensor as a reference, no other sensors read the O2 levals to make measurements. you can actualy take the O2 out of the unit and it will have no affect of the Co,HCN,H2S,PID or any of the other sensors as far as the way they detect gas.

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    Quote Originally Posted by jbrescue View Post
    I had the same thought. But, I am trying to find the life exptacny of the sensor. Some sensors last a year, some 5, some 6 months. We do not get a lot of fires and I think that spending this for something that will expire prior to use will be hard to sell. One of the guys that I know got a single gas from Rae, but has yet to try it out.
    On ours (Industrial Scientific), they have a one year warranty on all sensors, including the HCN. However, the sensor itself is pricey as is the cal. gas for it. They advised 1-3 years is typical of all their toxic gas sensors (which has been my experience as well with them since I do our maintenance, and typically see closer to the 3 year mark on most of ours), but the HCN will likely last closer to the lower end.
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    Hi all, just bumping this back up to see if anyone has any new information pertaining to this, particularly any studies related to post-fire CO level monitoring as a reliable indicator for safe HCN levels. Thanks in advance for any info.
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    We also have a 4 gas meter like fyrmnk said.

    We have been monitoring for several years now. At least on our meters, we can replace just one sensor if needed. It will still monitor for the other three.

    I'm not aware of any recent studies but if you find some information it would be nice to look at.
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