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  1. #1
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    Ploystyrene Extrusion Die's

    I've worked in extrusion across the globe for over 20 years. I've been told that the extruder die area is "exempt from being a Class 1 Division 1 area. Well now I'm being asked to prove the precedence. Does anyone know of where this exemption started or where I might find it?

  2. #2
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    Quote Originally Posted by WMBELEDES View Post
    I've worked in extrusion across the globe for over 20 years. I've been told that the extruder die area is "exempt from being a Class 1 Division 1 area. Well now I'm being asked to prove the precedence. Does anyone know of where this exemption started or where I might find it?
    I don't think there is one. is the area around it classified? if so it would appear that it would have to be at least D2.

    I have seen only a handful of plastic extrusion machines and I don't recall any were classified as being in a hazardous area. Maybe there is something special about polystyrene.

    as a practical matter maybe it is hot enough that it would not do any good to classify that space.
    Bob

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    Polystyrene Extrusion Dies

    Bob,
    If I were to use the definition of a C1D1 or D2 500.5(1&2) it might fall under D1 due to rare occurrence where an operator could inject a bubble of gas into the extruder that is released. If I read 500.5(2)(2), "Concentrations are prevented by positive mechanical ventilation". The plant has wall fans with ceiling louvers that replace quite a large volume of air, might this drop the Zone from D1 to D2? How might this be decided? Is there a more detailed article for testing to determine a zone? If so, is this a self test or a test of a certified mature?

    Bill

  4. #4
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    Quote Originally Posted by WMBELEDES View Post
    Bob,
    If I were to use the definition of a C1D1 or D2 500.5(1&2) it might fall under D1 due to rare occurrence where an operator could inject a bubble of gas into the extruder that is released. If I read 500.5(2)(2), "Concentrations are prevented by positive mechanical ventilation". The plant has wall fans with ceiling louvers that replace quite a large volume of air, might this drop the Zone from D1 to D2? How might this be decided? Is there a more detailed article for testing to determine a zone? If so, is this a self test or a test of a certified mature?

    Bill
    What kind of gas is it? If it is not flammable it would likely not matter.

    Part of classifying an area involves judgement and experience. It might be that experience has shown the risk is very low so it does not need to be classified.
    Bob

  5. #5
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    Polystyrene Extrusion Dies

    Quote Originally Posted by petersonra View Post
    What kind of gas is it? If it is not flammable it would likely not matter.

    Part of classifying an area involves judgement and experience. It might be that experience has shown the risk is very low so it does not need to be classified.
    Flammable, butane and pentane. Our experience shows risk is low but an inspector want's more than precedent.

    Bill

  6. #6
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    Quote Originally Posted by WMBELEDES View Post
    Flammable, butane and pentane. Our experience shows risk is low but an inspector want's more than precedent.

    Bill
    If you are unable to convince the inspector it might be necessary to hire someone with a PE after his name who has the experience and knowledge to be able to explain why it is that it does not need to be classified.

    It seems to me that the machine manufacturer would be a good place to start. I doubt their product liability insurer would let them sell a product like this that their insurer had not vetted first.
    Bob

  7. #7

    Ploystyrene Extrusion Die's

    Quote Originally Posted by WMBELEDES View Post
    Bob,
    If I were to use the definition of a C1D1 or D2 500.5(1&2) it might fall under D1 due to rare occurrence where an operator could inject a bubble of gas into the extruder that is released. If I read 500.5(2)(2), "Concentrations are prevented by positive mechanical ventilation". The plant has wall fans with ceiling louvers that replace quite a large volume of air, might this drop the Zone from D1 to D2? How might this be decided? Is there a more detailed article for testing to determine a zone? If so, is this a self test or a test of a certified mature?

    Bill
    Bill,

    If your plant layout representing the equipment markings found on nameplate's coincide with NEC 505.9(C)(2). Below is the Title of the information included.

    "Guidelines for the safe use of flammable blowing agents in the production of extruded polystyrene boards (XPS)"


    Tag this link:

    https://www.giz.de/expertise/downloa...safety-xps.pdf

  8. #8
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    Quote Originally Posted by nec_addicted View Post
    Bill,

    If your plant layout representing the equipment markings found on nameplate's coincide with NEC 505.9(C)(2). Below is the Title of the information included.

    "Guidelines for the safe use of flammable blowing agents in the production of extruded polystyrene boards (XPS)"


    Tag this link:

    https://www.giz.de/expertise/downloa...safety-xps.pdf
    Do you actually read (or understand) the stuff you google? You're addicted to google, not the NEC. And you still keep misapplying what you find. This paper is a great example of how IEC Zone 1 is often closer to NEC Division 2 than Division 1.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  9. #9
    Successfully the attempt to put things in perspective 505.9(A)(3) reiertrate exactly what you taught us in this thread pertaining to "owners engineering judgment".

    Of course if you do not feel that was the idea then have it your way.

  10. #10

    Polysterene Dies

    Quote Originally Posted by rbalex View Post
    Do you actually read (or understand) the stuff you google? You're addicted to google, not the NEC. And you still keep misapplying what you find. This paper is a great example of how IEC Zone 1 is often closer to NEC Division 2 than Division 1.
    Thank you :Anyone with as much experience with this portion of the code to simply dismiss NEC 501.5 and respond in such a manner should just allow an interrogative stated in the code and move on. It is plain to me.

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