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Thread: Dip tank operations

  1. #1
    Join Date
    Sep 2006
    Posts
    9

    Dip tank operations

    All,

    I need your help. I have an operation where we soak circuit boards in a solvent to remove an adhesive coating. The solvent resides in a covered 11 gallon dip tank. The process currently takes place in in a room that is designed for Class I Division 1 operations. The solvent being used is xylene (Class II combustible liquid, Flash point 81 deg F, boiling point 138 deg F).

    My operations folks would like to move the operation to a vented hood in another part of the plant. The hood in this case is not explosion proof.

    Question: Are there any electrical wiring requirements applicable to Class II liquids? I found plenty on Class I liquids but not much on Class II.

    I'm leaning towards saying 'no' on the basis of "Just because you can does not mean you should". However, some code backup would be useful.

    Thanks,

    MikeCJ

  2. #2
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,860
    Keep leaning. According to NFPA 497 [2017], Table 4.4.2, xylene is a "true" Class I (Flammable) Liquid.
    Last edited by rbalex; 08-24-17 at 06:24 PM.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  3. #3
    Join Date
    Sep 2005
    Location
    Greenville SC
    Posts
    663
    Quote Originally Posted by mikecj View Post
    All,

    I need your help. I have an operation where we soak circuit boards in a solvent to remove an adhesive coating. The solvent resides in a covered 11 gallon dip tank. The process currently takes place in in a room that is designed for Class I Division 1 operations. The solvent being used is xylene (Class II combustible liquid, Flash point 81 deg F, boiling point 138 deg F).
    It's been many MANY years, but my employer in around 1970 had a vapor degreaser with ultrasonic tank to do a similar task. With the refrigerated lines in the upper portion, there was no odor of the solvent; I think we were using trichlorethylene, obviously not OK any more, and not flammable.

    Point being, perhaps a condensing portion could be considered suitable to isolate the fluid and vapors. I doubt it, but?

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