Thank you for the respons.
So we need to ask for the proper documentation of this oxygen storage room if it was classified as Class 1 Division 1.
Here is the link where I found out that even oxygen tanks can be combustible.
There are two general causes of oxygen regulator fires, adiabatic heating and particle ignition
www.ems1.com
Not the same as a standard or a peer reviewed study or something like that. That article is written as recommendations on proper handling but it isn’t a consensus safety standard so should only be used absent any other guidance.
I’m not buying your conclusion. To create a fire you need a fuel AND oxygen plus a minimum ignition temperature and be within the lower and upper flammability limits. Oxygen by itself is NOT combustible. You can’t burn it...it’s not a fuel source by itself. We assume oxygen is normally present by way of the atmosphere and classify areas based on the fuels present, NOT oxygen by itself. You have the cart before the horse.
Oxygen it does promote combustion and alters the temperatures and flammability limits. That’s why it gets special treatment. By way of example many plastics such as nitrile hit their autoignition temperatures in an oxygen rich atmosphere at room temperature. For this reason putting on my process engineer hat oxygen by itself is NOT flammable. But pay attention closely to the materials present because things generally not considered flammable suddenly can be. I have a good friend that burned his hands severely while wearing nitrile gloves because an oxygen line was leaking and nobody knew it, at room temperature. Lots of crazy things happen even at mild elevated oxygen levels.
But this also indicates you can’t be C1/D1. In a division 1 condition the fire hazard is normally present. This is the case for instance in a coal mine or near coal processing equipment or say in a natural gas storage facility or in many parts of a refinery where the processing equipment is open to the atmosphere. In a division 2 environment it is not normally present but can on occasion be present. Generally this is the area where there needs to be a double failure. For instance you have an oxygen leak AND a faulty light switch. This is not an all
Inconclusive rule. Conditions that are rare such as maintenance activities, equipment that rarely leaks, etc., don’t count and make it unclassified. 497 talks more about these concepts.
But it would be a serious mistake to start with NFPA 497. Start with the most specific Code. In this case it’s NFPA 98 which covers gas bottle storage in healthcare facilities, THEN the more generic 55 which is the generic cryogenic gas Code, and only then refer to 497 if the first two don’t cover it. This is as per 497. Most NFPA Codes give very specific design requirements on piping, procedures, etc. Then those procedures tell you what the classification is under those standards. NFPA 497 only applies if all other Codes fail to provide guidance.
So..,research the most specific Codes first, then fall back to NFPA 497 ONLY if the more specific Codes don’t give guidance.
MANY PEs don’t get this and come up with some really badly screwed up recommendations based on their own guessing and attempts to do things. 497 actually says to do it this way but they skip over the first chapter. That would be like skipping over article 90 or 110 in NEC. If this all seems like something doesn’t smell right to you, that’s because it does smell bad.
NEC has several ways to qualify as outside the area. Don’t try to get creative.
