Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15

Thread: New Chemical

  1. #11
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    5,191
    It is important to remember that NFPA 497 is a Recommended Practice. (Read the title) So is API RP 500. I value both of them highly and, as ANSI Standards, FedOSHA holds them both in high reqard as well; however, a locally adopted Code like the NEC trumps an RP in any court.

    I am assuming from the Part you cited (5.5.6) you are referring to an to an outdated edition of NFPA 497. The 2017 edition is the latest and I will be referring to it later. Part 5.6.6 [2017] contains the same material you cited. You may find the last sentence of Part 5.5.4 of the edition you are using interesting as well - assuming you have the requisite "experience", of course.

    Technically, the NFPA 497 Figures are only a recommendation. Of course you do have to “draw the line somewhere” and they represent the consensus judgement of history. However, you should also refer to NFPA 497 [2017 edition] Parts 5.8, 5.9, and 5.10. You will note none of the Parts mention “batches” as part of the underlying analysis.

    As I said earlier, "I'm not there" so whatever you (and your insurer) are happy with is fine with me.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  2. #12
    Join Date
    Mar 2003
    Location
    New York
    Posts
    1,037
    Any room to build an isolation wall?

  3. #13
    Join Date
    Apr 2008
    Posts
    375
    No room for an isolation wall. Our HAC committee is taking matter under its control and they are using this thread couple with other feed back obtained to determine the area classification bubble. Once that's established then the fun work of bringing anything in that bubble up to code.

  4. #14
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    5,191
    If you have it available, API RP 500, Annex D provides a sound alternate analysis to the Figures. It can be tedious, but it still isn't "rocket science". What is "rocket science" is Annex B; just kidding, but it is far more analytic and you would probably discover it didn't make any difference in your case.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  5. #15
    Join Date
    Jul 2017
    Location
    Alberta, Canada
    Posts
    32
    I agree that the best alternative would appear to be getting away from NFPA 497 and using an alternative standard.

    IEC 60079-10 is quite analytical, but can sometimes result in reduced area classifications. Also API RP 500, as Bob said.

    Also, adding supplementary ventilation and/or cranking up local ventilation may help - some.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •