Q: Are there any storage requirements for full small calibration gas cylinders? The tanks are secure in that they are in holders; however, they are stored under a shelf in a workstation where the machine that uses them is set up. They normally have about 4-6 small cylinders.
A: Yes, there are requirements for small calibration gas cylinders, but it sounds like you have it covered. NFPA 99 requires all medical compressed gas containers to be properly secured and to separate full cylinders from empty cylinders. Now, compressed gas used for calibration may or may not be required to comply with NFPA 99 based on the interpretation by the authority surveying your facility. But since there are multiple authorities who survey your facility, it is best to be conservative and treat calibration gas cylinders the same as medical gas cylinders.
Once you accumulate 300 cubic feet of compressed gas within a single smoke compartment, you then need to store the compressed gas in a designated room that has door that can be locked, and oxidizing gases need to be stored at least 20 feet from combustibles, or 5 feet from combustibles if the room is protected with sprinklers. However, a few small cylinders of calibration gas do not amount to 300 cubic feet so you are probably okay storing them where you are currently doing so.
NFPA 99 requires full cylinders to be separated from empty cylinders, but does not address partially full cylinders. This is a requirement of the standard so no one will accidentally grab an empty cylinder during an emergency. Since partially full cylinders are not full cylinders, then the presumption is they need to be stored with the empty cylinders. Joint Commission has published guidelines that they would like to see partially full cylinders separated from both full and empty cylinders, but this is not a standard requirement.