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Thread: Thoughts on the hazardous classification of an extraction process using hexane.

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    Thoughts on the hazardous classification of an extraction process using hexane.

    I'm seeking thoughts regarding the hazardous classification of a process. I have a customer with an extraction process which uses hexane to extract a petroleum based oil from a plastic. For decades personnel at the plant have felt this aligns with NFPA 36: Standard for Solvent Extraction Plants. I just spoke with an NFPA representative that said since I am not extracting an animal or vegetable oil or fat (which is what NFPA 36 was written for) that I need not comply with it and instead fall under NFPA: Flammable and Combustible Liquids Code.

    What she said makes sense, however I cannot get past the fact that my process is that of extraction using hexane. I do not understand why the type of oil being extracted changes how I classify the area as the oil is not the hazard.

    I am most concerned with fully understanding this as my customer, since construction of their facility, have followed NFPA 36. The distance at which associated equipment is placed in relation to the extractor is one example of how they've followed NFPA 36. If I am to eliminate the controlled and restricted areas introduced by NFPA 36 and reduce the area considered Class I, Div 1 or Class I, Div 2 I will need to be able to make a strong argument.

    Any thoughts on this is greatly appreciated.

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    Quote Originally Posted by jmoore284@gmail.com View Post
    I'm seeking thoughts regarding the hazardous classification of a process. I have a customer with an extraction process which uses hexane to extract a petroleum based oil from a plastic. For decades personnel at the plant have felt this aligns with NFPA 36: Standard for Solvent Extraction Plants. I just spoke with an NFPA representative that said since I am not extracting an animal or vegetable oil or fat (which is what NFPA 36 was written for) that I need not comply with it and instead fall under NFPA: Flammable and Combustible Liquids Code.

    What she said makes sense, however I cannot get past the fact that my process is that of extraction using hexane. I do not understand why the type of oil being extracted changes how I classify the area as the oil is not the hazard.

    I am most concerned with fully understanding this as my customer, since construction of their facility, have followed NFPA 36. The distance at which associated equipment is placed in relation to the extractor is one example of how they've followed NFPA 36. If I am to eliminate the controlled and restricted areas introduced by NFPA 36 and reduce the area considered Class I, Div 1 or Class I, Div 2 I will need to be able to make a strong argument.

    Any thoughts on this is greatly appreciated.
    First off, I would ask what is your motivation for trying to get rid of these areas.

    Secondly, I don't know how "qualified" the NFPA representative you spoke to actually is. She might be and she might not be. I would not be using a brief, casual conversation as the basis for classification.

    One of the things that is scary to me about area classification is that it is often done based on this kind of sketchy advice. My suggestion is that if you do not know from your own experience or something that is documented in some professional text or standard, that you pay a qualified person to make this judgement call. This is especially true IMO since you seem to find the advice given to be somewhat dubious.
    Bob

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    From NFPA 36:

    "Chapter 1 Administration

    1.1 Scope.

    1.1.1* This standard shall apply to the commercial scale
    extraction processing of animal and vegetable oils and fats by
    the use of Class I flammable hydrocarbon liquids, hereinafter
    referred to as "solvents."" (Emphasis added)

    OTTOMH, I'd say you have three options:

    1. Read NFPA 36 §1.1.1 strictly, meaning it does not apply. You go find a different standard for classification, probably starting with NFPA 497.

    2. Reason that although you are not extracting edible oils, you are using a Class IB flammable solvent (hexane). Meaning NFPA 36 still applies, so you use that.

    3. Comply with both: one or more general standards (i.e. NFPA 497, NFPA 70) along with applicable requirements from one or more specific standards (i.e. NFPA 36).

    Given the situation and the pre-existing NFPA 36 compliance - and if it were me - I would default to (3) until I had opportunity to thoroughly review at least NFPA 36, NFPA 70 and NFPA 497. Only afterwards would I be able to decide which were most applicable, or if one did not apply at all.

    NFPA standards are, as a rule, fairly well aligned with each other, and all based on similar principles. From this, and from past experience, I would expect that the area classification for hexane from NFPA 497 is not likely to be meaningfully different than that from NFPA 36. I've not looked, however, so I could be wrong.

    I suspect that while there will be parts of NFPA 36 that will not apply, there is likely to be some aspects that are entirely applicable. Making (3) the safer choice.

    You are also correct in that you will need a strong argument to reduce the default areas, in which case you're going to want to have all the information possible. A broader review may show reasons why you should not implement reductions, which would be good to know.

    Just my $0.015143 $USD.

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    Quote Originally Posted by IntrinsicSafety View Post
    From NFPA 36:

    "Chapter 1 Administration

    1.1 Scope.

    1.1.1* This standard shall apply to the commercial scale
    extraction processing of animal and vegetable oils and fats by
    the use of Class I flammable hydrocarbon liquids, hereinafter
    referred to as "solvents."" (Emphasis added)

    OTTOMH, I'd say you have three options:

    1. Read NFPA 36 §1.1.1 strictly, meaning it does not apply. You go find a different standard for classification, probably starting with NFPA 497.

    2. Reason that although you are not extracting edible oils, you are using a Class IB flammable solvent (hexane). Meaning NFPA 36 still applies, so you use that.

    3. Comply with both: one or more general standards (i.e. NFPA 497, NFPA 70) along with applicable requirements from one or more specific standards (i.e. NFPA 36).

    Given the situation and the pre-existing NFPA 36 compliance - and if it were me - I would default to (3) until I had opportunity to thoroughly review at least NFPA 36, NFPA 70 and NFPA 497. Only afterwards would I be able to decide which were most applicable, or if one did not apply at all.

    NFPA standards are, as a rule, fairly well aligned with each other, and all based on similar principles. From this, and from past experience, I would expect that the area classification for hexane from NFPA 497 is not likely to be meaningfully different than that from NFPA 36. I've not looked, however, so I could be wrong.

    I suspect that while there will be parts of NFPA 36 that will not apply, there is likely to be some aspects that are entirely applicable. Making (3) the safer choice.

    You are also correct in that you will need a strong argument to reduce the default areas, in which case you're going to want to have all the information possible. A broader review may show reasons why you should not implement reductions, which would be good to know.

    Just my $0.015143 $USD.

    I appreciate the feedback. Since the post I've spoken with two of the technical committee members for NFPA 36. It appears the main reference to vegetable and animal fats/oils is in section 1.1.1 as you stated. There also are a few diagrams that make reference but not all of them. Other references in the document such as in the Origin and Development section make general references to the solvent extraction processes. The references to the edible oils likely stems from the bulk of the technical committee being from that form of processing. Not sure how many solvent based extraction plants are in operation in North America that extract non-edible oils.

    After our conversations the recommendation has been to follow NFPA 36 as our process is virtually identical to the process described in it. Unfortunately there is a big difference in boundaries between other NFPA standards for hexane and NFPA 36. NFPA 36 specifies larger Class I, Division 1 and Division 2 boundaries and goes on to add a 50' restricted boundary and 100' controlled boundary. If I were to follow NFPA 30 my extractor building would be considered Class I, Division 1 and that is it. By following NFPA 36 this building will be Class I, Division 1; an area 15' beyond the building will be Class I, Division 1, and I then will have my restricted and controlled boundaries.

    Our next move is to contact our Authority Having Jurisdiction (our local fire inspector) to see what they want us to follow. My bet is that we will need to comply with NFPA 36.

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    Quote Originally Posted by jmoore284@gmail.com View Post
    Our next move is to contact our Authority Having Jurisdiction (our local fire inspector) to see what they want us to follow. My bet is that we will need to comply with NFPA 36.
    If you are going to the AHJ and asking them to take responsibility for the decision, you are right to expect the most restrictive interpretation and you sort of tied your hands in reclassifying.

    I'm interested to learn what the goal is in trying to reclassify. Why does the owner wish to eliminate restricted and controlled boundaries? Consider the goal with respect to the added risk (which I'm certain you have already done based on your posts). Do workers want to smoke cigarettes outside the entrance, where there is shade... or are the regular maintenance activities made difficult by the existence of said boundaries?

    I don't presume you know the answers, but it seems odd to me to de-classify an area that has always been treated as such. Whoever designed the facility likely faced the same problems you are facing and decided NFPA 36 was the prudent approach. If you recommend to remove or shrink boundaries, and there happens to be an accident, whether a direct result or not, your phone will be ringing.

    Hope you get it all straightened out. Best of luck!

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    FWIW, I agree that talking to the NFPA committee members was a good approach. They're the ones who have the best understanding of the standard.

    The AHJ, on the other hand, might not know. A lot of AHJs want to see a classification from an engineer or other qualified professional, but they themselves are not qualified to evaluate said classification. There are exceptions but many AHJs have to deal with a lot of different situations, and they can't possibly be qualified to evaluate all of them. Hence the requirement for a qualified and appropriately accredited independent expert to do the evaluation.

    I'm not at all convinced you can go to NFPA 30. Given that NFPA 36 is specific to extraction processes, and NFPA 30 is not, NFPA 36 seems obviously more applicable. It seems highly unlikely to me that NFPA 30 would adequately cover the hazards specific to your process. Hence the larger classified areas from NFPA 36 - they're there for a reason.

    It may be possible for a qualified professional to reduce the classified areas below those specified in NFPA 36. Obviously this will require careful consideration, and is not possible in all instances. So you shouldn't count on it.


    Based on this, it seems the original question of moving away from NFPA 36 has been answered: you shouldn't, since it is the most applicable standard. Therefore, the original area classification of the plant is correct, and should not be altered. The current decades-old practices at the plant can and should continue uninterrupted. Not a bad result, really, since the plant obviously works and changes are always disruptive.

    It would be possible to check / update the original classification, based on the latest version of NFPA 36. But as this is unlikely to result in any meaningfully useful changes, it may or may not be worth the effort.

    It would also be possible to check / update the working practices at the plant, to correct for any normalization of deviation over the decades. This may be well worthwhile.

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    I think it is quite possible that there was some overly conservative classification that went on when the area was originally classified, as that seems to be pretty common. I think you need to pay an appropriate professional to take a look at the situation and make a determination as to whether what is there now is appropriate or not, and whether it can be safely changed to be less restrictive. There always seems to be resistance to doing this for some reason. I don't quite understand why. If you need a brain surgeon you cannot expect free advice from the internet or other sources to be of much real value in eliminating the need to pay a brain surgeon. Spend the money on someone who actually knows.
    Bob

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    If this process and all the supporting structures, equipment, etc. are already in place, and you are all ready (as far as I can tell) following the most restrictive standard, who is compelling the use of a less restrictive standard? I'd just say "Thanks for your opinion, we'll just keep doing what we're doing." After all, codes and standards are the minimum. If you've accidentally used a more stringent safety regime, who can criticize you?

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    Quote Originally Posted by gadfly56 View Post
    If this process and all the supporting structures, equipment, etc. are already in place, and you are all ready (as far as I can tell) following the most restrictive standard, who is compelling the use of a less restrictive standard? I'd just say "Thanks for your opinion, we'll just keep doing what we're doing." After all, codes and standards are the minimum. If you've accidentally used a more stringent safety regime, who can criticize you?
    Since the "more restrictive" standard being used clearly states it does not apply to the situation the OP finds himself in, I don't see how you can justify at least not looking at a "less restrictive" standard. It might be that extracting animal and plant fats and oils via a HC solvent creates some kind of potential hazard that does not exist in the OP's situation.
    Bob

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    Quote Originally Posted by petersonra View Post
    Since the "more restrictive" standard being used clearly states it does not apply to the situation the OP finds himself in, I don't see how you can justify at least not looking at a "less restrictive" standard. It might be that extracting animal and plant fats and oils via a HC solvent creates some kind of potential hazard that does not exist in the OP's situation.
    It sounds like they are already used to doing it the hard way. Why open a can of worms if you don't have to? If it ain't broke, don't fix it.

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