Vintage Double Hose

I want to swap the manifold on a set of doubles. Should the o rings be replaced or just examined and lubed? How tight should the valves be socked down? If it matters I will be installing a 3/4 inch Dacor manifold on a pair of aluminum 50's. While I have done this before I figure it is about time I found out how to do it right.

Thanks.

As cheap as a couple of O rings are just change them. Just slightly more than hand tight.

Thanks, I was also looking at some Luxfer documentation and they recommend Dow Corning Compound 111 on the threads for aluminum tanks. Is this the best practice for aluminum tanks? What about steel tanks, is it recommended to treat the valve with something to avoid corrosion?

Thanks.

Yes, Dow 111 is good on the threads for Alum. and Steel tanks.

Is Christolube a good lube to use on Tank O Rings as well as on internal orings for the double hose regs?

You can use Christolube, it a bit more compatible with high O2 mixes. If you just use air the Dow Corning silicone is good enough.