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Thread: A good way to explain Class I Div 1 & 2

  1. #1
    Join Date
    Feb 2004
    Posts
    267

    A good way to explain Class I Div 1 & 2

    During a recent discussion of Class I Division 1 requirements, I explained it this way:

    Class I Division 1 means I can pour gasoline on the machine and it will keep running without igniting it.

    Class I Division 2 means that I can pour gasoline on the machine and I can shut it down before it ignites, and when it is off it won't ignite the gasoline.

    I know I omitted the group here but that complicates the explanation. Anyone who's ever tried to re-start a charcoal grill after re-lighter fluiding it or used gas to start burning leaves or scrap, knows from their unsuccessful (or maybe successful) attempt at winning a Darwin award, how easy it is to start the fire/explosion.

    If anyone has better analogies, feel free. When you specify equipment for a classified location, the accountants become apoplectic and need a good answer where they walk away understanding, not thinking that maybe they're being techno-bs'd.

    Matt

  2. #2
    Join Date
    Aug 2004
    Posts
    10
    I'm not sure why you would need an analogy....

    Class I Division I:
    Where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or some of the time under normal operating conditions.

    Class I Division II :
    Where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions.

  3. #3
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,013
    Part of the problem with your analogy is that you probably wouldn’t shut down the process in a Division 2 location either.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

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