From the Luxfer Scuba Cylinder inspection guide, p21:
Quote:
We recommend that all straight thread valves be installed in Luxfer high-pressure aluminum scuba cylinders with a torque recommended by the valve manufacturer for aluminum cylinders.
Without a recommended torque from the valve manufacturer,we would recommend a torque of 50 lbf-ft, plus or minus 10 lbf-ft. All torquing should be done such that valve, valve components and cylinder are not damaged.
and also (same page):
Quote:
The application of a small quantity of lubricant to the valve threads is essential for the proper care of the valve and cylinder. We recommend that only Dow Corning Compound 111 be used on valve threads. Only a very small amount of the lube is needed, and only applied at the bottom of the valve threads. The lubricant will ride up the threads as it is installed. We only recommend this lubricant since it has proven compatible with cylinders and valves, doesn’t add any grease or oil to the cylinder, is safe to use, and helps prevent galvanic corrosion.
The complete guide can be downloaded
here
I could not locate recommended torque for Sherwood, Thermo or MDE valves, and did not find any more info on the Faber or Eurocylinder websites.