NFPA 11.2.2.2 Clarification, Industrial Enclosure Seperation

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zb2554

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NFPA 11.2.2.2 states, "Pipelines, tubing, or devices for handling air, gases, or liquids shall not be located in enclosures or compartments containing electrical control equipment."

Would the "devices" mentioned here include a bulkhead mounted, pneumatic pressure switch like the one linked below.
http://www.clippard.com/part/MAS-1B2-65


If the pressure switch is mounted through the enclosure wall all pneumatic lines and connections are made outside the enclosure.
 
Presumably you are referring to standard NFPA 79. I don't see how what you are suggesting is a violation of that standard.

Let me ask you a question is an enclosure with some solenoid valves mounted on the inside and some terminals that they wire to covered by this paragraph. I think if you wanted to mount it inside of a box you could as long as there wasn't any control equipment there. Personally I don't consider terminals to be control equipment.
 
Sorry, I wasn't clear enough in my post.

Yes, I am referring to NFPA 79 and there would be control equipment inside the enclosure, including a PLR.

Since the pneumatic lines and connections are outside the enclosure it didn't come across as cut and dry to me as trying to mount a solenoid valve inside the same box as control equipment.

The pneumatic process would occur outside the enclosure and push a mechanical switch inside, but there is always the risk the pneumatic seals would fail allowing air into the control enclosure.

I should list the exceptions for this paragraph also:

" Exception 1: Equipment for cooling electronic devices.
Exception 2: Pipelines, tubing, or devices that are an integral part of listed equipment and are separated by a suitable barrier."
 
Pipelines, tubing, or devices for handling air, gases, or liquids
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I think you have to ask yourself a question about what is actually inside the box.

It is not a pipeline or tubing.

Whether it is a "device(s) for handling air, gases, or liquids" is a matter of interpretation. Personally I am not convinced a pressure switch "handles" anything.

If it bothers you, why not just mount the switch on the outside of the box, or in a separate junction box.
 
This is a new one to me. Where I work, we have a few cabinets that run large systems that have all the pneumatic components mounted in the cabinet along
with electrical controls. They use compressed air only, no gases, nothing flammable. I don't see any reason this would be a hazardous practice.
 
Aleman said:
This is a new one to me. Where I work, we have a few cabinets that run large systems that have all the pneumatic components mounted in the cabinet along
with electrical controls. They use compressed air only, no gases, nothing flammable. I don't see any reason this would be a hazardous practice.
Click to expand...

Agree - I don’t know when this rule came about, but I used to design compressor control panels that included solenoid valves, pressure switches and associated tubing. Of course, that was more than a few years ago!
 
zb2554 said:
I was just curious what others interpretation would be.

Thanks for the replies.
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I think you answered your question in your original post.

"If the pressure switch is mounted through the enclosure wall all pneumatic lines and connections are made outside the enclosure."

Pneumatic lines and connections made outside the enclosure. I would interpret that as being compliant to this rule. In the meantime,
I won't lose any sleep over our panels that have all pneumatics inside the enclosures. We're probably compliant anyhow since these
panels would have predated this rule. Foolish rule in my opinion.

 
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