Replacing hose on regulator...what lubricant to use for threads? Urgent!

[herman]

I agree with all of this except them being static in service. The pressure deforms the o-ring every time the valve is turned on. It moves, and then relaxes when pressure is released.

I agree, just easier for most to picture them as static once installed so I don't worry too much about that detail. I spent a lot of hours reading up on orings and their sealing surfaces a while back......partly because I am geeky and partly because I was machining oring ports at the time.

 

[Papasmurf89]

What type of lubricant do you guys use for lubricating O-rings?

 

[tbone1004]

it depends on what it's being used for. On my O2 and deco regs, I use Tribolube 71, on everything else i use Dow 111

 

[herman]

I never use O2 mixes higher than 36 so Dow 111. There is no need for high cost lubes if you don't use high O2 mixes.

 

[Hickdive]

As you tighten the thread into the first stage the o ring needs a tiny amount of lube to stop it being twisted as you tighten. Once tightened the o ring isn't going to move again. However, if you're doing this on your own reg then, frankly, spit will do that without you having to buy a tube of grease. Over lubricating the o rings and then diving in hot weather can lead to o ring extrusion.

There is no need to lube hose end threads, they are chromed brass and do not corrode although the exterior of the hose end sometimes suffer from salt build up, ironically increased by slapping grease on everything.

 

[Dive Right In Scuba.]

it depends on what it's being used for. On my O2 and deco regs, I use Tribolube 71, on everything else i use Dow 111

Yes, the high oxygen lubricants are definitely more expensive than spit, but that's what I use. When you consider how very little you use, the price per application is actually not high at all. Now if you rarely do something like this, it might not make sense, but if you work with regulators fairly frequently, it should not be a big setback to have the good stuff on hand.

Aerospace Lubricants Tribolube 71 | Dive Right In Scuba - Plainfield, IL - Dive Right in Scuba

 

[Mr Carcharodon]

If all your metal parts have been really well cleaned a very little bit of grease on the threads can be a good idea to prevent galling. As already noted greasing the o-ring to help it seat well is more important. This is a case where less grease is more. Krytox works for me. Cristo-lube seems to be a emulsion (of oil and teflon?) and separates over time. It's OK for this sort of application, but less good for piston o-rings.

 

[Hatul]

I never use O2 mixes higher than 36 so Dow 111. There is no need for high cost lubes if you don't use high O2 mixes.

I assume Dow 111 is the standard silicone grease we use. I find the silicone grease to last longer and be more water resistant than Tribolube 71. I've noticed this on my Zeagle BX power inflator which gets wet on every dive. With the Tribolube, the thing needs to be taken apart more frequently to keep from sticking. The Tribolube is like a cream emulsion, whereas the silicone is more like a clear grease gel.

---------- Post added December 24th, 2015 at 01:57 PM ----------

OK, so another related question. Do you use any grease on the DIN reg threads or the DIN O ring?

 

[Akimbo]

The orings on the hose to the regulators are static so no lube required...

The O-ring connection at the second stage is a “classic dynamic seal” because the second stage is designed to swivel on the hose under pressure. The 3/8" LP boss at the first stage end is a “classic static seal” because the sealed metal parts don’t move relative to each other while under pressure.

… Hose orings are not static by definition and therefore do require lubrication for assembly….

I concur, although “all” instead of “hose” would be more precise. Perhaps this illustration from the Parker O-Ring Handbook will help others understand the concept of why your statement is accurate.

 

[noj3333]

Not to hijack this thread, but I have to install my LP BCD inflator hose on my first stage. Would lube be needed in that application or is it not needed/ optional?