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July 22, 2003
Valve insertion procedures for oxygen service using straight-threaded brass valves with O-ring seals
- Inspect the valve and cylinder for damaged threads and damaged O-ring seating surfaces, which must be clean and free of visible defects such as burrs, dings and gouges.
- Check for the Luxfer “oxygen clean” symbol
 on the cylinder crown. This symbol shows that the cylinder has been cleaned for oxygen and nitrous oxide service. Inspect the cylinder interior to verify cleanliness before inserting the valve.
- Install a new O-ring, making certain that it is clean, dry and free from physical damage. Do not lubricate the O-ring or valve threads. Lubrication is not necessary and may not be compatible with a high-pressure gaseous oxygen environment. Do not use the type of Teflon® tape used for plumbing and pipes. Only Teflon tape with special tolerances for oxygen service may be used. When in doubt, do not use Teflon tape.
- Carefully slip the O-ring over valve threads and fully seat it against the bottom of the flange.
- Assemble the valve to the cylinder and tighten by hand. If the valve fails to start easily, re-inspect for damaged threads.
- The following are maximum recommended torque values for Luxfer aluminum cylinder valve threads:
Straight threads only:
| Thread size |
Maximum torque |
| ¾-14 NGS |
100 lbf-ft (135.58 N x m) |
| .750-16 UNF |
75 lbf-ft (81.34 N x m)1 |
| .875-14 UNF |
80 lbf-ft (108.46 N x m) |
| 1.125-12 UNF |
100 lbf-ft (135.58 N x m) |
- Lightly close the valve handwheel.
- For instructions concerning proper valve operation, as well as information about safety relief devices and burst discs, please consult the valve manufacturer.
- Caution: Do not overfill cylinders. Fill cylinders only to the stamped service pressure at 70ºF.
NOTE: This Luxfer Technical Bulletin is only a general guideline. If you have specific questions not covered by this bulletin, please contact Luxfer Customer Service at 800-764-0366 or contact the valve manufacturer.
FOOTNOTES:
1 Note that this Luxfer torque value differs from that recommended by the Compressed Gas Association. Although CGA recommends 60 lbf-ft, Luxfer tests have shown conclusively that in certain Luxfer cylinders, the 75 lbf-ft torque value is preferable.
 
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