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Thread: Ventilation System for CID2

  1. #1
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    Ventilation System for CID2

    Are ventilation system motors required to be identified for Class I Division 1, if the area classification is CID2? To clarify, imagine an existing facility that has standard ventilation at around 6 exchanges of air per hour. Process equipment will be located in this facility. Is it possible to use the same ventilation equipment, or will it have to be redone to include ventilation motors that are identified for CID1 or can the motors simply be identified for CID2?

    I know it is kind of a chicken and the egg problem. Without the ventilation, the area would obviously become C1D1. But with the ventilation, it is CID2. I have studied NFPA 70 (2017) and API RP 500, and do not see any information stating that the ventilation system needs to be identified for CID1...but for some reason I think I read somewhere that the motors have to be explosionproof or otherwise identified for CID1...
    Time is of the essence, and I am low on essence. ~ Graham Hill

  2. #2
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    You probably should be looking at NFPA 45 and 496. NFPA 496 will describe what appropriate actions should be taken where various ventilation schemes fail.

    There are cases where motors in Class I, Division 2 must still be identified for Division 1, especially small single-phase motors.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    For my example, I am wanting to consider a room that is not classified and has a standard ventilation system. If I wanted to put process equipment in that room that would cause the room to be classified CID2, would the ventilation system have to be renovated to include Explosion Proof motors? My confusion stems from the fact that the CID2, without the ventilation being there, would be CID1.

    The motors for the ventilation fans themselves are well outside of the CID2 classification area. I do not see anything in NFPA 70 that specifically addresses this, and API RP500 touches on it some but not specifically about motor identification.

    It would make sense to me that the motors would have to at least be identified for CID2. I am comfortable with this as long as it is not a recommended and normal practice to make these motors identified for CID1...
    Time is of the essence, and I am low on essence. ~ Graham Hill

  4. #4
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    Quote Originally Posted by fifty60 View Post
    ...

    It would make sense to me that the motors would have to at least be identified for CID2. I am comfortable with this as long as it is not a recommended and normal practice to make these motors identified for CID1...
    How are motors identified for Division 2?
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    To meet the 2017 NFPA 70, ideally the motor would be identified by the manufacturer as CID2. Otherwise, if no manufacturer declaration or labelling, then ensuring that there are no sliding contacts, centrifugal or other types of switch mechanisms or integral resistance devices employed within the motor. The identification would come from the requirments for the suitability of identified equipment found in 500.8(A)3, which says that a manufacturer's self evaluation should be (wording and italics mine) acceptable.

    I would not be the manufacturer of the motor itself, but I am the manufacturer of the final equipment employing the motor. So I would take 500.8(A)3 to be applicable for the suitability of the entire equipment employing the motor.

    And then specifically use The Article 100 definition of identified is "Recognizable as suitable for the specific purpose, function, use, environment, application, and so forth...", and this would be done by an Engineer evaluation to ensure no slidng contacts, centrifugal or other types of switch mechanisms or integral resistance devices employed within the motor.
    Time is of the essence, and I am low on essence. ~ Graham Hill

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    HVACR Considerations

    The thing on Explosion Proof HVAC RTUs is its not just the indoor fan drives that are setup that way, its the entire unit even down to the compressor electrical entrances, condenser fan motors etc. and they are major expensive.
    In one of our facilities which is Class 1, Div. 2 we were spec'd with a 100% Outside Air unit, which does not have to be explosion proof as its not drawing any return air from the conditioned space. I have heard os some rooms that are spec'd for slight positive pressure, but I would think slight negative is more the rule.
    It seems to depend on close interaction with all the parties involved including the Architectural Firms Engineers who are responsible for that side of the job.
    It involves carefully defining the Scope of exactly what has to be protected against and how its going to be done.
    Microwave Radiation Dangers should be openly discussed

  7. #7
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    `

    Quote Originally Posted by fifty60 View Post
    To meet the 2017 NFPA 70, ideally the motor would be identified by the manufacturer as CID2. Otherwise, if no manufacturer declaration or labelling, then ensuring that there are no sliding contacts, centrifugal or other types of switch mechanisms or integral resistance devices employed within the motor. The identification would come from the requirments for the suitability of identified equipment found in 500.8(A)3, which says that a manufacturer's self evaluation should be (wording and italics mine) acceptable.

    I would not be the manufacturer of the motor itself, but I am the manufacturer of the final equipment employing the motor. So I would take 500.8(A)3 to be applicable for the suitability of the entire equipment employing the motor.

    And then specifically use The Article 100 definition of identified is "Recognizable as suitable for the specific purpose, function, use, environment, application, and so forth...", and this would be done by an Engineer evaluation to ensure no slidng contacts, centrifugal or other types of switch mechanisms or integral resistance devices employed within the motor.
    That's a bit overboard, but not too bad; however, with rare exception, motors are not identified by the manufacturer for Division 2. In fact, except for explosionproof motors, NEMA motors are not listed/labeled in NEC terms. Some NEMA motors are UL Recognized Components (the backward UR you may see), but UL specifically states in the White Book and other UL documents that a Recognized Component is not listed/labeled. So you won't get anything from the manufacturers.

    As an additional lesson. Check the UL Online Certifications Directory and enter "pthe" in the UL Category Code box. It will link to all the UL listed Division 2 motor manufacturers. You will notice from the "Link to File" column, that most are foreign, all are for special applications, and, if you dig deep enough, not necessarily for "typical" Division 2 applications. You will also see none of them are NEMA manufacturers (even the GE Mexico plant).

    So now it's up to you. How would you identify a motor for Division 2?
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    I would ensure that there are no sliding contacts, centrifugal or other types of switch mechanisms or integral resistance devices employed within the motor. I would then also ensure that the maximum surface temperature of the motor is less than 80% of the AIT for the Hazardous material.

    All of that, to me, is pretty straight forward for a CID2 area. But, when it comes to an actual ventilation system, for circulating/recirculating the air, would those fan motors need to be identified for CID1? Or, would motors identified for CID2 suffice?
    Time is of the essence, and I am low on essence. ~ Graham Hill

  9. #9
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    Quote Originally Posted by fifty60 View Post
    ...I would then also ensure that the maximum surface temperature of the motor is less than 80% of the AIT for the Hazardous material....
    And how would you do that?
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  10. #10
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    I would have to look at the insulation rating, for example a motor designated class F with a 1.15 service factor has an allowable average winding temperature rise of 115 degrees centigrade. This motor has a total temperature of 155 degrees centigrade with the inclusion of the 40 degrees centigrade maximum allowable ambient temperature. The surface frame temperature would be less than the winding temperature.
    Time is of the essence, and I am low on essence. ~ Graham Hill

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