Class 1 Div 2 ????

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dgengr

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I?m going to try to explain what I?m dealing with the best I can and hope you guys have some input. I am currently working with a company that is the sole manufacture of a piece of equipment that ultimately produces methane gas. Now keep in mind I am a manufacturer I have no design freedom, just building to the owner?s specs.
There is an enclosed area on this equipment that is considered Class 1 Div 2. However the components in this area are not all classified. ?components include pumps, blowers, instrumentation, automated valves, and remote IO? Its has always been my understanding that a classified area is just that, therefore all electrical components should meet that classification????? Please correct me if I?m wrong?
I have asked these questions of the owner but do not get a clear answer. The basic response is if the component is not classified, then if gas is detected by ?CH4 sensor? then the program will turm the non-classified components off??????????????? It seems to me ?though very unlikely? there will be a very short time between detecting gas and shutting down that a spark could be present???
Again I have tried to give a decent description any incite is appreciated.
 
dgengr said:
I?m going to try to explain what I?m dealing with the best I can and hope you guys have some input. I am currently working with a company that is the sole manufacture of a piece of equipment that ultimately produces methane gas. Now keep in mind I am a manufacturer I have no design freedom, just building to the owner?s specs.
There is an enclosed area on this equipment that is considered Class 1 Div 2. However the components in this area are not all classified. ?components include pumps, blowers, instrumentation, automated valves, and remote IO? Its has always been my understanding that a classified area is just that, therefore all electrical components should meet that classification????? Please correct me if I?m wrong?
I have asked these questions of the owner but do not get a clear answer. The basic response is if the component is not classified, then if gas is detected by ?CH4 sensor? then the program will turm the non-classified components off??????????????? It seems to me ?though very unlikely? there will be a very short time between detecting gas and shutting down that a spark could be present???
Again I have tried to give a decent description any incite is appreciated.
Click to expand...
well....

most I/O systems these days are listed as C1D2, other than the parts that have relays built into them.

motors only have to meet the requirements of 501.125(B). this is not a difficult standard to meet.

a lot of instruments are also C1D2 already.

as for valves it is hard to say. if they are pneumatically controlled they should be OK. motorized valves are usually not OK due to the limit switches inside them. However there are some that are made that have actuators that come C1D2.

i do not believe a gas analyzer is an appropriate means of protection.
 
dgengr said:
I?m going to try to explain what I?m dealing with the best I can and hope you guys have some input. I am currently working with a company that is the sole manufacture of a piece of equipment that ultimately produces methane gas. Now keep in mind I am a manufacturer I have no design freedom, just building to the owner?s specs.
There is an enclosed area on this equipment that is considered Class 1 Div 2. However the components in this area are not all classified. ?components include pumps, blowers, instrumentation, automated valves, and remote IO? Its has always been my understanding that a classified area is just that, therefore all electrical components should meet that classification????? Please correct me if I?m wrong?
I have asked these questions of the owner but do not get a clear answer. The basic response is if the component is not classified, then if gas is detected by ?CH4 sensor? then the program will turm the non-classified components off??????????????? It seems to me ?though very unlikely? there will be a very short time between detecting gas and shutting down that a spark could be present???
Again I have tried to give a decent description any incite is appreciated.
Click to expand...
The saving grace (period) here is that the methane will be present in detectable concentrations before it is present in explosive concentrations. That gives a time lag dependent on the size of the leak and the freedom of the gas to diffuse and disperse from its origin to the detector. Whether that is enough for safety would require a lot more detailed knowledge.
My untutored first take would be that if the (infrequent) presence of methane gas can be detected in such a way that the non-classified components can be de-energized, then those components will not be operating in a classified area, just present. Just how the letter and spirit of the regulations deal with that is beyond my knowledge.
Just as mandatory ventilation can prevent an area from being classified that otherwise would be, the detection and shutdown might serve the same function.

Implicit in what you describe is that the apparatus as a whole, and in particular the classified components would continue to operate. At least long enough to do an orderly shutdown? That makes me think that it would allow the methane concentration to increase for awhile after detection (unless the blowers, etc. could thoroughly ventilate the area.)
 
If this is a manufactured piece of equipment then I am not sure that the NEC would apply. Would this product not have to go to a 3rd party testing after it is built?
 
petersonra said:
well....

most I/O systems these days are listed as C1D2, other than the parts that have relays built into them.

motors only have to meet the requirements of 501.125(B). this is not a difficult standard to meet.

a lot of instruments are also C1D2 already.

as for valves it is hard to say. if they are pneumatically controlled they should be OK. motorized valves are usually not OK due to the limit switches inside them. However there are some that are made that have actuators that come C1D2.

i do not believe a gas analyzer is an appropriate means of protection.
Click to expand...

So 501.125(b) Would a TFC motor meet the requirment?

The valves are pneumatically actuated, however the switches on them are not rated C1D2. Anouther issue i have is all the valves switches are wired into IO distrobution blocks that are not rated "8 port M12 conection distrobution blocks"
 
Dennis Alwon said:
If this is a manufactured piece of equipment then I am not sure that the NEC would apply. Would this product not have to go to a 3rd party testing after it is built?
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It is a manufactred piece of eqipment, however very large. Think of this as "manufactured home/ Methane plant" No Alabama joke please...
 
I realize size matters sometimes...:D but I am not convinced it does in this case. I will leave this to the more experience.
 
It is very hard to tell you much more than we have without having a fairly detailed set of drawings to look at.

TEFC motors are probably OK as long as there are no switches, brushes, or heaters involved.

Just out of curiosity what is your involvement in this? Are you designing some part of it? An end user?

A piece of equipment this size could conceivably have an area that is div 2 that is relatively small. Presumably the manufacturer of the equipment has a better idea of just what is needed.

Just why some part of the equipment is classified might be relevant.
 
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I don?t like gas detection. Unless and until NFPA creates a standard similar to NFPA 496 (purged/pressurized) for gas detection schemes, the NEC applications are very limited. See Section 500.7(K). There are only three recognized applications [Sections 500.7 (1), (2) AND (3)] and your description so far doesn?t seem to fit any of them if you read them carefully. Note none of the recognized applications even refer to shutdowns in case of gas detection. Some of the references in IN/FPN 1 do, but they aren?t enforceable ? and you still have to construct to Division 2 as a minimum anyway.

Methane has a fairly narrow range of flammability. Unfortunately the LFL is low enough that going from a detectable level to LFL can be very fast.

Personally, I?d get a qualified NRTL on board.
 
rbalex said:
Note none of the recognized applications even refer to shutdowns in case of gas detection[...] ? and you still have to construct to Division 2 as a minimum anyway.
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Yes, all that the gas detection does is increase the assurance that hazardous concentrations will not be present during normal operation, without requiring the same high level of confidence that a leak will not happen. And all it does is effectively reduce the area from Division 1 to Division 2.
Hopefully the OP will be in a position to lobby for NRTL or other expert involvement. We also do not know where this equipment is designed to be used (although I can make some guesses.)
 
Based on the OP's description of the equipment, it does not seem like it should be all that hard to make it suitable for C1D2, if it is not already.
 
petersonra said:
Based on the OP's description of the equipment, it does not seem like it should be all that hard to make it suitable for C1D2, if it is not already.
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I agree if they are dealing with a knowledgable inspector. I suggested a NRTL primarily because the OP didn't seem too comfortable. I've had entire powerhouse type substations (up to 20MVA) and a 153MW generating station listed/labeled (depending on the NRTL). The cost was reasonable and it greatly simplified the approval process.
 
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