Class 1, Division 2...i think

[drbond24]

I have a situation where a customer wants to install gas cylinders in a room already containing a panelboard, wire in conduit, etc. Does this mean I must replace all the electrical equipment in the room with Class 1, Division 2 equipment? Also, what if the cylinders were outside the room and only the piping went through the space with the panelboard.

It seems to me that either way, the space is Class 1 Div 2 and I need to replace the panelboard with one in a NEMA 7 enclosure and replace all conduit with threaded rigid steel.

I would just like a second opinion.

 

[rbalex]

The room may, in fact, be Division 1 rather than Division 2 ? or it may even be unclassified. There are too many undisclosed variables in your OP description to give a complete answer. Pressure and volume of the bottles, ventilation, delivery method of the piping, valving, etc. all play a part in determining the proper electrical area classification.

Assuming the room is correctly classified as Division 2, the electrical equipment would indeed need to be made suitable.

 

[rcwilson]

Do the bottles contain a hazardous gas?

Depending on the gas properties, the storage and piping pressure and the volume stored, it may be possible to locate the bottles in another area and run just the piping through the room. The piping would have to be all-welded, with no screwed fittings, valves, instruments, flanges, or other leak sources. Then the room might be able to remain unclassified if the storage room is sealed and isolated from the room containtng electrical equipment.

 

[drbond24]

The bottles do contain hazardous gasses. Hydrogen, methane, and ethylene are among them. Where does the requirement to weld the piping come from? I don't see it in NEC 500. It is likely the bottles will be placed outside the space and piped in, so if welding the pipe and specifying no valves, etc. leaves the space unclassified, that is definitely the route I want to take.

FYI: The pressure will only be 5-10 psi. I don't know the volume of the cylinders, but they are physically the same size as welding tanks.

 

[rbalex]

The "other" Bob and I are referring to 500.5(B)(2) FPN No.2. It is sort of a synopsis of considerations from NFPA 30, 58 and more importantly 497.

With the pressure and volumes you are citing, if the area is well ventilated, I probably wouldn't classify it at all. I would still want to know more details before I "stamped" an area classification document though.