Announcement

Collapse
No announcement yet.

Class 1 Div 2?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Class 1 Div 2?

    The company I work for designs and builds vacuum degreasing cleaning units. We are considering using modified alcohol solvents in a future design. The solvent rep told us that units sold overseas using their solvents are considered nonhazardous. He believes our units will not need to be class 1 div 2 but the NEC 2014 Article 500.5 (2) (1) says different. However I maybe misunderstanding Article 100's definition of "Volatile Flammable Liquid". The modified alcohol solvents we are considering have flash points of 142°F & 151°F.
    Please let me know your thoughts.
    Thank you!

    #2
    Are the solvents being handled above their flash points at some point in the process? If not, there is no concern.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2017 NEC unless otherwise noted.

    Comment


      #3
      Originally posted by rbalex View Post
      Are the solvents being handled above their flash points at some point in the process? If not, there is no concern.
      Yes they will be above the flash points. We vaporize the solvent while under vacuum as part of our process. The boiling point for the solvent is between 300 & 400°F

      Comment


        #4
        In that case, proper electrical area classification will depend on other factors such as piping and mechanical construction, ventilation, possible fugitive emissions, etc. It is still possible that the location, exterior to the equipment, is unclassified but I personally would need a far better understanding of the overall process to make that evaluation.
        "Bob"
        Robert B. Alexander, P.E.
        Answers based on 2017 NEC unless otherwise noted.

        Comment


          #5
          Originally posted by rbalex View Post
          In that case, proper electrical area classification will depend on other factors such as piping and mechanical construction, ventilation, possible fugitive emissions, etc. It is still possible that the location, exterior to the equipment, is unclassified but I personally would need a far better understanding of the overall process to make that evaluation.
          Attached is an explanation of the process with PCE (Perchloroethylene) as the solvent type in the example. The process for the modified alcohol will be almost exactly the same as the example.
          Attached Files

          Comment


            #6
            Originally posted by A-A-Ron View Post
            Attached is an explanation of the process with PCE (Perchloroethylene) as the solvent type in the example. The process for the modified alcohol will be almost exactly the same as the example.
            If I were to do the electrical area classification around this process, I would require a great deal more than this. I would probably spend a day interviewing the process, mechanical, and piping engineers. I might even want to talk to the civil/structural engineers. I would want detailed material flow diagrams with material balances. Detailed P&IDs. And applicable MSDSs. And the overall geometry layout of the facilities it was installed in including exterior process piping and ventilation design. I would probably find other things to ask about during the interview.

            The upside for you is that this would be the end-users responsibility in the first place. [NEC (2017) Section 500.4(A)] You still might need to provide the information I mentioned. As part of the evaluation, industry experience from overseas may be valuable [NFPA 497 (2017) Section 5.6] But I wouldn't count on my supplier's word except for the MSDS.
            "Bob"
            Robert B. Alexander, P.E.
            Answers based on 2017 NEC unless otherwise noted.

            Comment


              #7
              Originally posted by rbalex View Post
              If I were to do the electrical area classification around this process, I would require a great deal more than this. I would probably spend a day interviewing the process, mechanical, and piping engineers. I might even want to talk to the civil/structural engineers. I would want detailed material flow diagrams with material balances. Detailed P&IDs. And applicable MSDSs. And the overall geometry layout of the facilities it was installed in including exterior process piping and ventilation design. I would probably find other things to ask about during the interview.

              The upside for you is that this would be the end-users responsibility in the first place. [NEC (2017) Section 500.4(A)] You still might need to provide the information I mentioned. As part of the evaluation, industry experience from overseas may be valuable [NFPA 497 (2017) Section 5.6] But I wouldn't count on my supplier's word except for the MSDS.
              We have designed units in the past with Acetone. For these units, basically the electrical panels are purged and the motors and instrumentation are exposition proof. Modified alcohol is not as volatile as acetone but to err on the side of caution I was going to design the units the same. I just have to justify my design thus the initial question. We design, build and test everything in house then send it out. Typically the end-users heeds to our recommendation but not always. Attached is a picture of of our Class 1 Div units.
              Attached Files

              Comment

              Working...
              X