tbone1004:
Not sure where KWS' info came from on anything over 23.5 requiring things to be O2 clean, but since most of my diving and nitrox fills are in cave country, there are some "rules" that are blissfully ignored. I have yet to see anything official come out saying that, but I'm not current on PSI-PCI so it may be from them.
kelemvor:
Who sets those? Is it a government agency or a scuba certification agency or other? Just curious, it's the firs time I'd heard there was an actual standard.
This topic periodically comes up on SB, with the ‘discussion' usually going down a somewhat predictable path.
KWS is absolutely correct, about the 23.5% standard. And, the ’standard’ is one set by CGA (Compressed Gas Association) and PSI - PCI, and it is not new. Note, it is NOT federal
regulation. Although the CFR reflects CGA standards on many items, the OSHA threshold / standard is still 40%. And, this is one of those standards which poses no problem as long as something doesn’t go wrong. However, in the face of an oxygen fire, or similar event - with injuries / property damage / whatever - in a situation where a banked enriched air mixture of, say, 30% was put into a cylinder with appropriate enriched air markings, but which had not been cleaned for oxygen service, I suspect any smart plaintiff’s attorney would be quick to use the presence of CGA and PSI – PCI ‘standards’ to make a case for negligence. But, I suspect even PSI - PCI is not unrealistic about the actual implementation of the ‘standard’ in the SCUBA world (and I have discussed this with Mark on more than a few occasions). It is simply not practical to require that any cylinder which may be filled with a gas containing 23.5% - 40% oxygen to be cleaned for oxygen service. First of all, the workload for shops to attempt to provide oxygen cleaning (properly performed) for all the cylinders currently being used for Enriched Air would easily overwhelm the current availability of resources (staff, facilities, AND expertise) to do it. Secondarily, the added expense to the user / customer would be substantial. So, even though it is a CGA standard, and a PSI - PCI standard, and is mentioned in every PSI - PCI Visual Cylinder Inspection course, in every PSI – PCI Inspector Update course, and every PSI – PCI Oxygen Service Technician course (to mention just a few), it is simply not common practice.