Converting Dive Tanks For Oxygen Service With GMC Oxy-Safe Products
6. Compatibility and Replacement of Components: Certain internal parts should be replaced if actual oxygen-compatible components are available. Most scuba valves contain seats made of Nylon 6/6 which is not considered to be very oxygen-compatible. While Nylon 6/6 does have marginal oxygen-compatibility, field use has shown that pure oxygen and oxy-rich Nitrox slowly vaporizes that material, often resulting in a complete seat failure. Some manufacturers provide alternate seats containing recognized oxygen-compatible materials such as KEL-F. For example, Sherwood valve seats (Sherwood #3506-9K) contain Kel-F polymer, which will fit many valves that Sherwood-Selpac produced for other distributors over the years.
All nitrile O-rings, such as valve stem and bonnet seals, must be replaced by Viton or EPDM (Ethylene-propylene) material. The white backing rings used in most valves are Teflon and therefore are oxy-compatible. But these, and any other part that will come in contact with pure oxygen, must be cleaned prior to installation. Unless oxy-compatible parts are received from the manufacturer in a sealed package marked oxygen-clean, do NOT assume them to be oxy-clean. Clean them as you would other materials to be used in oxygen service.