A lot of great information in this discussion, but respectfully we must disagree with the opinions expressed that recommend lubrication, especially in regards to use with oxygen. Keep in mind our perspective is from the point of view of best practice regarding safety, because so many of our customers are actually using very rich oxygen mixtures.
The benefit of using lubrication during installation of valves in SCUBA cylinders is debatable. In our own research, we can't find any objective basis for recommending lubrication with properly maintained SCUBA tanks where the valve is removed and O-ring replaced on a periodic basis. Professional Scuba Inspectors (PSI) says in their manual Inspecting Cylinders - 5th Edition that "threads with O-ring seal do not require a lubricant." O-ring suppliers tell us that lubricating static O-rings, such as the neck O-ring, causes more problems than any dubious benefit it might provide. While oxygen compatible lubrication of threads and O-rings in SCUBA valves and cylinders is probably harmless under ideal conditions, it also has no clear benefit.
Generic cylinder and valve maintenance guides rarely address the specific nature of the SCUBA industry, especially in regards to Nitrox applications. Since the valve, O-ring and cylinder manufacturers in any assembled SCUBA tank are all different, it's commonplace to hear conflicting recommendations regarding use of lubricant. Our suppliers do agree that nearly all installation, sealing and removal problems are caused by improper technique and over-tightening the valve into the cylinder, not the absence of lubricant. Some local dive shops intentionally avoid all lubricant, some use it very sparingly and others use it liberally. The bottom line is that lubrication use in this SCUBA application seems to be a matter of opinion, not science.
Lubrication, even oxygen compatible lubrication, is not considered best practice for cylinders and valves used with medical oxygen or industrial oxygen. That's because while oxygen compatible lubricants might have higher temperatures of ignition than hydrocarbons, they can still serve as fuel in the kindling chain of an oxygen fire. Any lubricant will attract and retain contaminates, plus there is the significant risk that an incompatible lubricant might be applied. In our opinion, legitimate oxygen safety concerns outweigh the questionable benefits espoused by those recommending lubrication in Nitrox SCUBA cylinder and valve applications.
Based on oxygen handing best practices and advice of industry experts, Dive Gear Express currently does not recommend and does not use any form of lubricant, including oxygen compatible lubricant, with our Nitrox Ready SCUBA valves and cylinders.
