Q: We have a contractual Dialysis Unit on the 2nd Floor of our Medical Office Building which consists mainly of one large open room. Very often in the treatment area they have more than 12 ‘E’ size cylinders of oxygen stored, that are not in use. Does the 12 cylinder rule apply to them even though they are an ambulatory care occupancy?
A: By saying the 12 cylinder rule, you are referring to the NFPA 99 requirement that requires quantities of compressed medical gas that exceed 300 cubic feet per smoke compartment to be stored in a designated room that has 30 minute fire rated walls, a door with a lock on it, and kept separate from combustibles by 20 feet (5 feet if the room is sprinklered). 12 full ‘E’ size cylinders contain slightly less than 300 cubic feet of compressed gas, so 12 ‘E’ size cylinders per compartment could be stored outside of the designated room, but once there are 13 of them, then they would all have to be stored in the designated room. The healthcare occupancy chapters in the LSC do require compliance with NFPA 99 in regards to medical gas storage (see 18.104.22.168), but the ambulatory care occupancy chapters (20 and 21) do not. But that is not the end of the story. Oxygen by itself is not a flammable gas, but it can make other items burn faster and at a lower temperature. Therefore, it is considered a hazard, and must be protected in a room designated as a hazardous room. But at what point does the quantity of compressed oxygen stored in the cylinders becomes a hazard? If this were healthcare occupancy, the answer to that question is made for us by NFPA 99 which sets a threshold of 300 cubic feet of compressed gas. But that standard is not listed as a requirement in the ambulatory care chapter of the LSC, so the authority having jurisdiction (AHJ) will have to decide for themselves what standard to use. I suggest you follow NFPA 99 requirements for oxygen cylinder storage until such time an AHJ says otherwise.