Nitrox Compatible Lube Sources and the Necessity of Using for Ambient Chamber

[Mobulai]

I can understand that if the ambient chamber is filled with a non-O2 compatible lube/substance, the piston o-ring will effectively slide against the ambient chamber wall which could allow the substance to creep/migrate into the intermediate pressure area ahead of the piston head and contaminate that area....but that would only affect the areas down stream of the piston, the 2nd stages and their hoses.

Silicone is sticky and tough to get rid of (without through cleaning )

I wanna invoke 2020 hygiene mentality onto this, some silicone seeps out, some is on your hand, you use that hand to thread a DIN wheel, the threads have some of that silicone; the cylinder you just installed a reg on now has some silicone on the valve…
Fill station, another tank, another reg…

It’s a very long chain if events where the odds/risk keep decaying (maybe exponentially even) with each step, but not 0
Improbable but not impossible

Now assuming I’m at places where no m26 threads are invoked (like Dahab), and I decided to get a nx30 tanks for the dive and some nx50 for deco; next day I do a rebreather dive at the same shop, with Air dil (and 100%) and I use a silicone filled reg for my main tanks and eventually contaminated the deco tank I can see this turning a 100% tank/reg getting silicone in the HP air path

Even at places that have m26 separation, all it takes to some traces stuck on the hand and it transferring to a o2 reg/tank interface
It wouldn’t self combust once silicone touches it; but aligns some more holes in the swiss cheese model

This ofcourse doesn’t apply to the silicone that is on LP side that doesn’t ooze out from under a sealing boot


Another example (maybe even less likely) is how the packing technique is done; the piston stem is partially on both the LP and HP sides, only the stem oring separates them; with continuous motion/use I can see tiny traces creeping in
Probably will never the knife edge/seat area, but technically that HP side is now non o2 clean

Paranoid — sure, but I don’t wann to FAFO

 

[Geo7]

I am not understanding the "cross-contamination" argument some have made here, especially in the context of affecting a fill station.

I can understand that if the ambient chamber is filled with a non-O2 compatible lube/substance, the piston o-ring will effectively slide against the ambient chamber wall which could allow the substance to creep/migrate into the intermediate pressure area ahead of the piston head and contaminate that area....but that would only affect the areas down stream of the piston, the 2nd stages and their hoses.

How is that an issue on the high pressure end of the 1st stage? The non-o2 lube/substance Is not at the tank to first stage interface so how would there be a contamination issue/consideration at the fill station to tank interface?

-Z

Good points, and I actually do know some people that fill the chamber with cheap silicone, and use the modern lubes inside the rest of the reg. And these are friends that know what they are doing.

I should have been clearer in my point about cross-contamination: On the one hand it's a personal thing, because when I fill the environmental chambers I still manage to get Tribolube on me, my bench, my tools, etc (even though I have all the factory tools to do it). But in my defence, I read that Scubapro tested their techs during one seminar long time ago. If I understood correctly, it seems they had two sections (normal and O2 clean stations), but found that no one was able to prevent Silicone getting on the regs that were intended to stay o2 clean. My understanding is they then switched to Christolube for everything.

So my worry was more about a scenario where I work on a dirty air reg with silicone one day, and next day I am servicing an O2 reg, and cross-contaminate that with silicone from the previous day.

 

[Geo7]

Silicone is sticky and tough to get rid of (without through cleaning )

OMG, yes, that is the key factor why I rather avoid it if I need to keep some of my gear O2 clean.

 

[Mobulai]

So my worry was more about a scenario where I work on a dirty air reg with silicone one day, and next day I am servicing an O2 reg, and cross-contaminate that with silicone from the previous day.

I keep silicone only for non breathing seals like camera housings or torches ; I will wash my hands before handling a reg