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Thread: CID2 Power Supply in a Purged Enclosure

  1. #1
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    CID2 Power Supply in a Purged Enclosure

    I would like to install a CID2 rated power supply in a Type Z purged enclosure. The idea is to have the power supply power up before the cabinet is purged. Is it OK to have CID2 rated equipment power up on a Type Z purged enclosure before beginning the purge/pressurize process on the enclosure?

    It is a CID2 area. I do not see anything specifically forbidding this, and my conscious/judgment is not telling me there is anything wrong with doing this. But it is different than what I have seen in the past, mainly because I am used to Type X purge where this would not be allowed.

    I think as long as It is installed and all the wiring to it meet CID2 requirements, then it should be OK.
    Time is of the essence, and I am low on essence. ~ Graham Hill

  2. #2
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    Quote Originally Posted by fifty60 View Post
    I would like to install a CID2 rated power supply in a Type Z purged enclosure. The idea is to have the power supply power up before the cabinet is purged. Is it OK to have CID2 rated equipment power up on a Type Z purged enclosure before beginning the purge/pressurize process on the enclosure?

    It is a CID2 area. I do not see anything specifically forbidding this, and my conscious/judgment is not telling me there is anything wrong with doing this. But it is different than what I have seen in the past, mainly because I am used to Type X purge where this would not be allowed.

    I think as long as It is installed and all the wiring to it meet CID2 requirements, then it should be OK.
    With a type Z purge there is nothing that prevents the cabinet from powering up before it is purged anyway. On a power up from a power failure for instance, everything in the cabinet will power up without a purge since the purge is something done manually. The pressurization has kept the inside of the cabinet free from any hazardous gases. You only purge if you open the door typically.

    I don't even think the power supply needs to be rated C1D2 since the purge system is there to create a small volume of space that is essentially not classified and the power supply is in that unclassified space.
    Bob

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    The power supply would technically be to power the pressurizing system. NFPA 496 directs that since it is part of the pressurizing system, it should be identified for the classification that would exist in the absence of the pressurizing system.

    So it seems like if it was any other power supply in the cabinet it could be general purpose, but since it is part of the pressurizing system it is treated differently.
    Time is of the essence, and I am low on essence. ~ Graham Hill

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    Quote Originally Posted by fifty60 View Post
    The power supply would technically be to power the pressurizing system. NFPA 496 directs that since it is part of the pressurizing system, it should be identified for the classification that would exist in the absence of the pressurizing system.

    So it seems like if it was any other power supply in the cabinet it could be general purpose, but since it is part of the pressurizing system it is treated differently.
    What power is required for a type Z purge/pressurization system?
    Bob

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    The control unit I need to supply is 24VDC.
    Time is of the essence, and I am low on essence. ~ Graham Hill

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    Quote Originally Posted by fifty60 View Post
    The control unit I need to supply is 24VDC.
    Maybe they make type Z Purge units different these days but I've never seen a control unit on a type Z Purge system. I've seen pressure switches on them for alarming or display but I can't say that I've ever seen something I would call a control unit. On the other hand I can't say I've seen that many type Z Purge systems either.
    Bob

  7. #7
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    It controls the volume of purge gas flowing into the purged cabinetand maintains and monitors an overpressure relative to the ambient air when purging iscomplete. You can purchase the manual system as well that are not powered at all, but this one is automated with a user interface, etc.
    Time is of the essence, and I am low on essence. ~ Graham Hill

  8. #8
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    The short answer to the OP's question is: Yes, it is fine.

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