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Thread: Ventilation System for CID2

  1. #11
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    Quote Originally Posted by fifty60 View Post
    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?
    I think you should take a close look at 501.125 (B) for the motor.

    As for the ventilation system itself I am a little nervous about the recirculating part of your statement.
    Bob

  2. #12
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    Quote Originally Posted by fifty60 View Post
    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.
    Not bad, now you need to deal with petersonra's concern about recirculating a potentially hazardous atmosphere. (I was going to get to that)
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  3. #13
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    Understood, and I did not intend to say recirculating. The ventilation system is only there to provide interchanges of air, but it is not recirculating the inside air outside and then back inside. Any air coming back in to the room would be coming from a non-classified location.
    Time is of the essence, and I am low on essence. ~ Graham Hill

  4. #14
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    Quote Originally Posted by fifty60 View Post
    Understood, and I did not intend to say recirculating. The ventilation system is only there to provide interchanges of air, but it is not recirculating the inside air outside and then back inside. Any air coming back in to the room would be coming from a non-classified location.
    That’s the reason I suggested NFPA 496. It is a very comprehensive discussion of requirements for pressurizing a room.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  5. #15
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    Now to get back to the original discussion. Unless the motor is single-phase, it is unlikely that it will need to be identified for Division 1 or 2 if the rest of the protection techniques suggested in NFPA 496 are followed.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  6. #16
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    Forgive my previous comment. The motor does need to be identified for the location but it does not need to be marked for Division 1 or 2.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  7. #17
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    I would think that NFPA 496 would only apply to pressurized enclosures. I will read again to see what can be applied to rooms.
    Time is of the essence, and I am low on essence. ~ Graham Hill

  8. #18
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    Quote Originally Posted by fifty60 View Post
    I would think that NFPA 496 would only apply to pressurized enclosures. I will read again to see what can be applied to rooms.
    Read the Scope.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  9. #19
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    In order for a motor to be 'identified' for Class I, Division 2, and therefore meet 501.125(B), certain motor design parameters must be met - such as non sparking fan, (TEFC) and end plates cut/fit to prescribed tolerances suitable for CID2. There are 5 - 7 design requirements involved - it depends on motor size, voltage, etc.
    If the motor nameplate is not clearly marked, you should check with the vendor to ensure the motor is actually suitable for Division 2 before installing.

  10. #20
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    Quote Originally Posted by Dale001289 View Post
    In order for a motor to be 'identified' for Class I, Division 2, and therefore meet 501.125(B), certain motor design parameters must be met - such as non sparking fan, (TEFC) and end plates cut/fit to prescribed tolerances suitable for CID2. There are 5 - 7 design requirements involved - it depends on motor size, voltage, etc.
    If the motor nameplate is not clearly marked, you should check with the vendor to ensure the motor is actually suitable for Division 2 before installing.
    Have you ever seen a motor nameplate "marked" for Class I, Division 2? Post a nameplate screen shot or vendor's cut sheet that indicates it's marked.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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