Putting together a set of doubles for the first time....questions on lube & o-rings

[RaginCajun]

Dive Rite have a few excellent tutorials online detailing everything from rigging up doubles to the latest & greatest side mount rigging. However, after watching I still have a few details that seem to be missing. I'm sure this is obvious to someone out there, hence the post.

When changing out tank valves to accommodate a manifold, should you lube the o-ring in the tank neck? Of course, if the tanks are O2 clean already or intended for O2 service those O-rings need to be viton and the lube needs to be O2 compatible

Should you lube the o-rings in the manifold bar also?


Here are the links to putting the doubles together, attaching to a Trans-pac and rigging a stage bottle, all excellent short videos. Thanks Dive Rite.


Dive Rite TV channel, diving videos, dive gear videos, training videos: Dive Rite Scuba (http://www.diverite.com/tv/training-and-tips/82)

Dive Rite TV channel, diving videos, dive gear videos, training videos: Dive Rite Scuba (http://www.diverite.com/tv/gear/64)

Dive Rite TV channel, diving videos, dive gear videos, training videos: Dive Rite Scuba (http://www.diverite.com/tv/gear/62)

[Wookie]

No, do not lube the neck o-ring. Put a drop (and I mean a drop) of thread lubricant on the threads and spread it around. You may use an O2 safe product like christolube if you expect higher than normal levels of O2 (nitrox) in your doubles, or regular Dow Corning 111 if using air. It is a common problem to use too much thread lube then assembling cylinders. When putting the manifold together, I like to use a smear of lube on the manifold including the o-rings. Just enough to make the brass shiny, I do not goop it on.

With all that said, I'm sure someone will tell me I'm wrong, but my experience includes the assembly and disassemble of at least a couple of sets of doubles for hydro every year and 80 or so individual cylinders.

The rule of thumb is, don't lube static o-rings. This includes the one in your camera housing. The one in your camera housing might get lubed because you rub it every time you check it, not because you want heaps of grease on it. Overgreasing o-rings is the leading cause of failures, IMHO. Stuff sticks to the grease.

[halocline]

The old school thought is to not lube the tank neck o-ring because it functions more like a crush seal than an o-ring, and the lube could increase it's extrusion. I'm skeptical about that, but then again I don't see any reason to lube it either. It's only in a year, it gets deformed in installation and stays that way until you remove it.

The manifold o-rings I would lightly lube with PTFE grease, just like Frank suggested.

[Teller]

I lube both but very lightly.

[ajduplessis]

I use Cristolube on both thread and o-ring, but a very and I mean a very little amount. I do this with all my cylinders, stages and deco bottles.

[Colliam7]

When changing out tank valves to accommodate a manifold, should you lube the o-ring in the tank neck? No. There is no reason to lubricate the tank neck O-ring. (Similarly, you don't need to tighten the tank valve down more than hand tight, but a lot of people go for the big adjustable wrench and really crank the valve down needlessly.)
Should you lube the o-rings in the manifold bar also? No, there is no reason to lubricate the manifold bar O-rings.

Both of these are static O-rings. There is technically no reason to lubricate them.

Now, having said this, will you do significant harm by assuaging your uncertainty and (very lightly) lubricating them? Probably not, although the argument is made that any lubricant attracts contaminants and may contribute to problems with the static seal. I used to lubricate, but no longer do (after going through the appropriate 12-step program). I didn't die before because of lubricating them, and haven't died yet since I stopped lubricating them. (But, I am sure I will die at some time in the future, although most likely in a manner unrelated to whether or not I lubricate my static O-rings, or to diving in general, for that matter.)