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Thread: Persistence of Hazardous Area Classifications

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    Persistence of Hazardous Area Classifications

    Is it possible for a Hazardous Area (C1D2) to only be present for specific times during the day?

    For example, if the potential for leaks only exist during 1 hour during the day, the C1D2 area classification would only exist for that 1 hour during the day. I know that analysis would also have to be done for any below grade or other accumulation points, but if not considering that, in general, can a C1D2 area only exist during the times of day that the hazard can occur.

    I understand consistent care, procedure, and documentation would need to exist to facilitate this, but with all of that in place would it be a reasonable approach?
    Time is of the essence, and I am low on essence. ~ Graham Hill

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    I suppose it can, but I don't see how that will change what wiring methods/materials would be needed, once given a hazardous location designation you have to install things per that designation regardless of it being a part time occurrence.
    I live for today, I'm just a day behind.

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    Quote Originally Posted by fifty60 View Post
    Is it possible for a Hazardous Area (C1D2) to only be present for specific times during the day?

    For example, if the potential for leaks only exist during 1 hour during the day, the C1D2 area classification would only exist for that 1 hour during the day. I know that analysis would also have to be done for any below grade or other accumulation points, but if not considering that, in general, can a C1D2 area only exist during the times of day that the hazard can occur.

    I understand consistent care, procedure, and documentation would need to exist to facilitate this, but with all of that in place would it be a reasonable approach?
    Is the idea to change the protection method only during the projected times?
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    Yes, to allow general purpose equipment into the area during specific times during the day when the process is not running, and the hazard potential no longer exists..
    Time is of the essence, and I am low on essence. ~ Graham Hill

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    Quote Originally Posted by fifty60 View Post
    Yes, to allow general purpose equipment into the area during specific times during the day when the process is not running, and the hazard potential no longer exists..
    So, you are thinking to placard, "Arcing, open-flame devices not permitted 12:47 - 13:48"?
    And the reasoning is that a hot work permit and sniffer is required without the placard?

    No, I have never seen that.
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    Quote Originally Posted by fifty60 View Post
    Is it possible for a Hazardous Area (C1D2) to only be present for specific times during the day?

    For example, if the potential for leaks only exist during 1 hour during the day, the C1D2 area classification would only exist for that 1 hour during the day. I know that analysis would also have to be done for any below grade or other accumulation points, but if not considering that, in general, can a C1D2 area only exist during the times of day that the hazard can occur.

    I understand consistent care, procedure, and documentation would need to exist to facilitate this, but with all of that in place would it be a reasonable approach?
    No matter how infrequently a Division 2 (or 1 for that matter) location is "truly" hazardous, it is impractical for equipment and wiring methods to be other than that suitable for the base classification.

    Ice worm hit on the actual solution. Section 500.4(A) requires that classified locations be documented properly. A hot work permit fits the purpose of documenting and temporarily reclassifiying the location. I have been in some refineries that post such documentation daily for smoking zones.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    I'm thinking more along the lines of a fill process in an adequately ventilated space. The hazard only exists when the fill tool is filling the container. When the process is over, the tool is holstered in a different location. So during the fill process, the area around the fill process is Hazardous. But within a minute of ending the fill process the hazard has dissipated...I would like for the Hazardous Classification to only exist for the time during the fill and the time afterwards it takes to dissipate the hazardous mixture...
    Time is of the essence, and I am low on essence. ~ Graham Hill

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    Quote Originally Posted by fifty60 View Post
    I'm thinking more along the lines of a fill process in an adequately ventilated space. The hazard only exists when the fill tool is filling the container. When the process is over, the tool is holstered in a different location. So during the fill process, the area around the fill process is Hazardous. But within a minute of ending the fill process the hazard has dissipated...I would like for the Hazardous Classification to only exist for the time during the fill and the time afterwards it takes to dissipate the hazardous mixture...
    Assuming this is a "normal" operation, you do realize this describes a Division 1 application, right? See Section 500.5(B)(1)(1).
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    Sorry, not a very good description on my part. The potential for a hazard only exists during the fill. There is normally not a hazard because the process is sealed. But if there is a leak or malfunction then the hazard would exist, so it is Div 2. Sorry about my misstep there...when the tool holstered, it is away from the area in question and there is not potential for hazard

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    Quote Originally Posted by fifty60 View Post
    Sorry, not a very good description on my part. The potential for a hazard only exists during the fill. There is normally not a hazard because the process is sealed. But if there is a leak or malfunction then the hazard would exist, so it is Div 2. Sorry about my misstep there...when the tool holstered, it is away from the area in question and there is not potential for hazard
    Fine. In that case it will always be a Division 2 location even when the tool is “holstered”. See Section 500.5(B)(2)(1). Unless and until you can get CMP14 to revise the definitions (highly unlikely), the location for the scenario you propose will never be less than Division 2 in absence of a hot work permit.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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