Ventilation System for CID2

[fifty60]

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...

 

[rbalex]

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.

 

[fifty60]

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...

 

[rbalex]

...

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?

 

[fifty60]

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.

 

[StarCat]

HVACR Considerations

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.

 

[rbalex]

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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.

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?​

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[fifty60]

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?

 

[rbalex]

...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?

 

[fifty60]

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.

 

[petersonra]

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.

 

[rbalex]

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)

 

[fifty60]

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.

 

[rbalex]

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.

 

[rbalex]

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.

 

[rbalex]

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.

 

[fifty60]

I would think that NFPA 496 would only apply to pressurized enclosures. I will read again to see what can be applied to rooms.

 

[rbalex]

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.

 

[Dale001289]

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.

 

[rbalex]

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.