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

[knotical]

Lubricate both O-rings and threads.

from: http://www.anchorrubber.com/specialty/parker_o-lube.pdf

3.1.5 Lubrication
Lubrication of O-ring seals is extremely important for installation and operation of dynamic seals as well as proper seating of static seals. The general rule for use of lubrication is: The greatest benefit in using a lubricant is obtained during the initial installation of the O-ring

And some "light" reading here about thread lubricants:
https://books.google.com/books?id=N...AQgeMAE#v=onepage&q=lubricants thread&f=false

 

[dumpsterDiver]

I always try to put a thin coating of grease on the threads and on the O-rings of most anything I assemble. I honestly don't recall ever having a hose come unscrewed.

 

[oldschoolto]

If you want a really boring or great read depending on who you are...
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19780021508.pdf

Jim...

PS... I read the whole thing and found it very interesting... Oh... Add I lube the o-rings and threads with a very light film of lube..

 

[DogDiver]

Of course you could use WD-40. [emoji23]


Sent from my iPhone using Tapatalk

 

[uncfnp]

I haven't kicked this dead horse in a while so I will again.

Hose orings are not static by definition and therefore do require lubrication for assembly. While it is true they are static in service, they are not when being installed. To meet the definition of a static seal, the mating (sealing)surfaces must NEVER move past/ slide against the oring and since the hose orings move past the sealing surfaces both in rotation and linearly during assembly, they are by definition dynamic, not static. There are very few true static seals used in scuba, the yoke tank oring being one of the few that meet the criteria for being a static oring. Can you get away with not lubing them, most of the time yes and in reality if the connection is not new/ O2 cleaned, odds are there is some residual lube there anyway. I spent a lot of time reading and educating myself about oring seals years ago.

I will also disagree on lubing the SPG threads. The lube helps prevent corrosion and stops a lot of water intrusion into the threads, again reducing corrosion.

Hi herman and thanks for correcting this misinformation on my part. Don't know where I got that bad advice though I do admit it has worked well for me so far. Never had a hose o-ring fail. Just spool and tank o-rings. It seems odd that they are both considered dynamic (hose and spool) when there seems to be such a difference in their durability.

I have also read that unnecessary lube can attract debris but this seems to be a myth as well.

 

[oldschoolto]

I have also read that unnecessary lube can attract debris but this seems to be a myth as well.

Well, Not really a myth... In high dust and dirt environments the use of "DRY FILM LUBE" is recommended.. Extra grease like you see when people lube a ball joint can cause trouble... All extra lube should be cleaned from the outside surfaces...

Jim...

 

[dumpsterDiver]

For something like an underwater camera O-ring, you want to have the absolute minimum amount of grease, just a shiny coating. If you do use excess grease and are opening and closing etc, then this does give the grease the opportunity to attract dust and contaminants. For something like a regulator hose O-ring, the sand and grit will be locked out by the O-ring. The only time "attraction" of dirt could be an issue is upon disassembly - I would think.

I just took apart my second stage today and greased up the barrel adjustment knob threads and the O-ring too.

 

[gcarter]

Want another opinion. I use lube on every threaded connection and every o-ring. That thing about them not coming loose? Yeah, they might not the next time. I've taken apart the ones with lube and the ones without after years. The ones with come off. I use silicone grease. Christolube would be fine too if you are really worried about oxygen in breathing mixes, but I'm not up to the 36% I dive.

I own a tire store. We antisieze every lug. If our customers then go to the local Les Schwab they are told it will cost $100 to get that lube off, that lug nuts should never be lubed. One of my employees is a former employee of that Les Schwab and he really didn't want to use lube. After a few years he mentioned to me that our customers had almost no broken studs. Lube makes things tighten down better and come off easier. That o-ring that "doesn't move" in there actually compresses everytime you pressurize your reg. That is how it makes the seal.

Lubricant on studs is bad for the stud replacement business though.

Lubricant changes the dynamic considerably, including required torque values and resulting bolt / fitting stretch and thread deformation.

The only times I have ever broken studs have been a) vehicle has been sitting and rusting for an extended period, b) studs were over torqued on a regular basis, or c) nuts were cross threaded.

I follow manufacturer recommendations WRT lubrication and torque values.

I lubricate (lightly) the o-ring and leave the threads dry.

YMMV.

---------- Post added December 21st, 2015 at 10:48 PM ----------

For certainty, I just re-scanned the Apex service manuals for the XTX seconds and the DS series primaries. Lots of mention of lubricating o-rings, zero instruction to lubricate threads.

 

[BRT]

I haven't kicked this dead horse in a while so I will again.

Hose orings are not static by definition and therefore do require lubrication for assembly. While it is true they are static in service, they are not when being installed. To meet the definition of a static seal, the mating (sealing)surfaces must NEVER move past/ slide against the oring and since the hose orings move past the sealing surfaces both in rotation and linearly during assembly, they are by definition dynamic, not static. There are very few true static seals used in scuba, the yoke tank oring being one of the few that meet the criteria for being a static oring. Can you get away with not lubing them, most of the time yes and in reality if the connection is not new/ O2 cleaned, odds are there is some residual lube there anyway. I spent a lot of time reading and educating myself about oring seals years ago.

I will also disagree on lubing the SPG threads. The lube helps prevent corrosion and stops a lot of water intrusion into the threads, again reducing corrosion.

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.

 

[oldschoolto]

I love hanging out with you nerds.....

Jim.....