Attaching hoses to the regulator, 1st stage and spg

[tfsails]

To lube or not to lube? No need to lube static o-rings. Static o-rings to not see any motion between the parts they are sealing. Inboard (that screw into the first stage) hose ends are static.
Dynamic o-rings seal parts that move, like SPGs and second stages. They should be lubed. The outboard hose o-rings are dynamic.

If you don't have a pick, you can put a small amount of grease on the inside of the second stage fitting and it will transfer to the o-ring that's hidden by the b-nut on the hose. I lubricate every second-stage o-ring I install. Definitely lube the two #3 o-rings on the SPG bullet.

 

[Blue Sparkle]

tfsails,

Aha, good point on the second stage O-rings. Since they swivel like the SPG, that makes sense now that I think about it.

What do you use to lubricate the O-rings? I have heard Trilolube or equivalent, but I'm interested in what you choose.

Thanks,
Blue Sparkle

 

[Bubbletrubble]

What do you use to lubricate the O-rings? I have heard Trilolube or equivalent, but I'm interested in what you choose.

Tribolube 71 is my current o-ring lubricant of choice. I got a 2 oz. tube of it for a little over $20 for DIY regulator overhauls in 2009. In my limited experience, it seems to be quality stuff. Another recently discovered bonus is that some have reported it's OK to use Tribolube 71 on Canon UW camera housing o-rings. That's nice to know.

BTW, I lube the o-rings in the second stage end of LP reg hoses just like tfsails described. It makes no sense to try to remove, lube, then re-install this particular o-ring because the removal process typically induces significant trauma to the o-ring. (Probably has something to do with my poor o-ring pick skills.) If I'm replacing that o-ring, I'll simply lube it up prior to installing it.

As herman mentioned, it's best to put a generous helping of lube on the -003 HP spool o-rings. I generally subscribe to a less-is-more philosophy when it comes to o-ring lubrication...but this is one particular application where I slightly "over-grease." Minimal greasing leads to more frequent servicing of the HP spool (at least that's been my experience).

In case you're interested in purchasing o-rings for your dive locker, I found that Dive Gear Express has a convenient chart with common o-ring sizes. The viton o-rings sold by Dive Gear Express are excellent quality, but nowadays I use o-rings made of EPDM (also oxygen-compatible). I recall purchasing a bunch of 'em a few years ago from AOPtec.com.

 

[herman]

Problem is the hose oring does not meet the definition of a true static oring. While in service they are static they are in fact dynamic during installation. To be a true static oring there can be no relative motion between the oring and the mating surface at any time. During installation of the hose, the oring travels past it's mating surfaces until it seats so it is not a true static oring which is the reason I lightly lube hose orings. The only true static oring that is used in scuba is the yoke to tank valve orings.

 

[Tortuga68]

Problem is the hose oring does not meet the definition of a true static oring

It does from an engineering standard. By your defintion ALL o-rings are dynamic - even the yoke

 

[herman]

It actaully comes from the Parker O-ring Handbook page 1-5. a good read if you are interested in o-rings. The yoke to reg o-ring is static because there is no relative motion between the 2 mating surfaces and the oring, the surfaces are pressed together with no motion that would cause the mating surface and the oring to slide past each other....unless you rotate the reg with it attached which you should not do. Hose orings on the other hand, slide past their mating surfaces during installation therefore they are not by definition static. This motion can cause the oring to bind and deform unless lubricated. Granted the total length of the travel is small and the likely hood that the oring will deform is limited it is still a possibility.
I agree that true static oring are uncommon. A direct quote from the Parker manual "True static seals are generally quite rare".

As I typed I realized I have a good example of the deforming of this type of "static" oring. My Inon strobe has a fixed oring not unlike the one on a hose end and a cover that screws on over it, similar to the body of a reg. Because the cover is clear I can see the interaction between the oring and the cover. Even with it lubricated there is obvious deformation as it is being installed. If you go slow and allow it time to rebound it pulls itself back into shape but that would not be possible if it were not lubed.

Lube or not to lube is your choice, I lube based on the my study of the subject.

 

[Luis H]

For years, the “Parker O-ring Manual” has been generally considered the engineering standard for basic O-ring information.

Static O-rings are found on most face seal geometry.
Examples are:
Pipe flange with face O-rings
Face seals on some camera housings.
O-ring face seals are often found on many water proof/ pressure proof housings were the faces are brought together with screws (for example, some of the high end dive computers).

For the first stage hose O-rings I often prefer to use just a bit of silicone spray.