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Thread: Fluid Pumps

  1. #11
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    Quote Originally Posted by fifty60 View Post
    The pump motor is not in direct contact with the process fluid, so I agree that at that point it would be like any other motor spec'd for a Class I Div 2 location.

    I can't think of any pumps that pump a solid...so I could have been more specific to say liquid or gas instead of just fluid....since both are fluids, but are subsets of fluids.
    Excuse my pedantry.................
    Si hoc legere scis nimium eruditionis habes.

  2. #12
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    Pedantry is a curse to the holder, but a blessing to the beholder.

    I have another question related to this. So if the inside of the enclosure is Class I Div 2 Zone 2, whereas the hazardous material is only present due to a fault in positive ventilation, where does the Class I Div 2 Zone 2 area extend to.

    From NFPA 30, I get the following: "Area between 5 ft and 8 ft of any edge of such equipment, extending in all directions; also, space up to 3 ft above floor or grade level within 5 ft to 25 ft horizontally from any edge of such equipment" (the wording of this doesn't seem to add up to me for some reason)

    So is this taking the positive ventilation into account? Isn't it mechanically forcing the air out of the enclosure, so wouldn't that potentially extend the range? I would think that without ventilation, the area would be Class I Div 1, but with ventilation it is Class I Div 2. So isn't the area it is ventilating too become Class I Div 1, or does the ventilate area just extend the Class I Div 2 boundaries based off of the area of classification dictated in NFPA 30?
    Time is of the essence, and I am low on essence. ~ Graham Hill

  3. #13
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    Please don't mix Zones with Classes it adds nothing but confusion.

    Sent from my XT1585 using Tapatalk

  4. #14
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    If the center is Div 2, then the surrounding area cannot become Div 1.
    And normally the area around Div 2 is unclassified, AFAIK.
    The effect of the exhaust in extending that is not clear to me. A lot would depend on where the outflow went. A tall stack would dissipate it nicely.

    Sent from my XT1585 using Tapatalk
    P.S. Churchill is said, when taken to task for ending a sentence with a preposition, to have replied: "That, sir, is errant pedantry, up with which I shall not put!"
    Last edited by GoldDigger; 09-09-17 at 01:15 AM.

  5. #15
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    I am looking at table 7.3.3 in NFPA 30 2015, and it puts forth the "extent of the classified area". The table, imo, is a little bit confusing. It says that for Class I Div 1, the zone extends "Area within 5 ft of any edge of such equipment, extending in all directions". That is straight forward.

    However for Class I Div 2 it says the area extends "Area between 5 ft and 8 ft of any edge of such equipment, extending in all directions; also, space up to 3 ft above floor or grade level within 5 ft to 25 ft horizontally from any edge of such equipment"

    It seems to me like the area of extent for Class I Div 2 is more severe than for a Class I Div 1. I've reread this more than 10 times trying to sort through the ambivalence of the wording, but it still does not make sense. To me, the Class I Div 2 area wording almost says that the zone skips the first 5 feet surounding the edges of the equipment, and does not start until 5-8 feet in totality, and then 5-25 feet 3 feet above the ground. What about the first 5 feet surrounding the edges?
    Time is of the essence, and I am low on essence. ~ Graham Hill

  6. #16
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    Quote Originally Posted by fifty60 View Post
    I am looking at table 7.3.3 in NFPA 30 2015, and it puts forth the "extent of the classified area". The table, imo, is a little bit confusing. It says that for Class I Div 1, the zone extends "Area within 5 ft of any edge of such equipment, extending in all directions". That is straight forward.

    However for Class I Div 2 it says the area extends "Area between 5 ft and 8 ft of any edge of such equipment, extending in all directions; also, space up to 3 ft above floor or grade level within 5 ft to 25 ft horizontally from any edge of such equipment"

    It seems to me like the area of extent for Class I Div 2 is more severe than for a Class I Div 1. I've reread this more than 10 times trying to sort through the ambivalence of the wording, but it still does not make sense. To me, the Class I Div 2 area wording almost says that the zone skips the first 5 feet surounding the edges of the equipment, and does not start until 5-8 feet in totality, and then 5-25 feet 3 feet above the ground. What about the first 5 feet surrounding the edges?
    It seems to me that there is only one type of equipment being considered, and the first five feet around it will be Div 1, while the area from 5 to 25 below 3 feet and 5 to 8 in any other direction will be Div 2.
    You are asking how far Div 2 extends from Div 2 equipment, which does not seem like the right question to ask.

  7. #17
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    Ah, that makes sense now. It is still odd to me that a cabinet that without ventilation would be considered Class I Div 1, but with ventilation it is considered Class I Div 2, that there is not any guidlines for the area around the actual ventilation components....It seems like the ventilation considerations would have to carry over into the area that the cabinet is being vented in to...
    Time is of the essence, and I am low on essence. ~ Graham Hill

  8. #18
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    It seems like the Class I Div 2 area would extend, based off of the installation, to the entire area around the machine in question that could become hazardous due to the malfunction in the machine that would make the machine Class I Div 2.

    I think the danger I am trying to avoid is that you could ventilate the enclosure to make it class I Div 2, but the area you are ventilating in to could easily become Class I Div 1 if that area itself is not well ventilated. For example, if I ventilated the enclosure into a sealed off room, eventually the room would become Class I Div 1...but so would the enclosure since the air it is getting from the room to ventilate would be coming from Class I Div 1..

    So it seems that calculations need to be done on the machine itself to keep it ventilated properly, but similar calculations need to be done in the room that the equipment is installed in to make sure that it does not become hazardous.

    I think that is all elementary reasoning in regards to Hazardous areas...

    It seems like the entire machine ventilation method depends on the area of installation being adequately ventilated to begin with. How do you guarantee that the area the machine is installed is always ventilated?
    Last edited by fifty60; 09-09-17 at 09:11 AM.
    Time is of the essence, and I am low on essence. ~ Graham Hill

  9. #19
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    well whats the "stuff"?

  10. #20
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    The stuff in question is flammable refrigerant. The equipment in question has a pump that flows the refrigerant in the liquid state. The reason I am interested in ventilation is to reduce the equipment to Class I Div 2. The reason I think that without ventilation, it could be considered Class I Div 1 is that by the nature of this type of equipment, leaks are pretty inevitable. They are by no means normal, but they are inevitable given time and use.

    I always considered Class I Div 1 to be locations where the flammable substance is expected to be present during normal operation. I then always considered Class I Div 2 to be locations where the flammable mixture is only present during a fault of some kind.

    Looking more at the definitions, Class I Div 1 can also include situations that flammable mixtures are present due to "frequent" leaks.

    I am not sure what "frequent" means, and I am not sure how to determine if leaks in A/C equipment should be considered frequent. I would definitely prefer that the eqipment be Class I Div 2 as opposed to Class I Div 1. For example, Class I Div 1 will allow me to use type Z purge instead of type X or Y.

    If the leaks in the equipment can be determined to not be frequent enough to qualify as Div 1, then I also would not have to add forced ventilation to the enclosure to reduce it to Div 2.
    Time is of the essence, and I am low on essence. ~ Graham Hill

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