Why adjustment knobs might matter

[lexvil]

Personally I slather this stuff everywhere south of HP O2 for big corrosion protection-lubrication-sealing

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NASA use inspired (not that there is anything wrong with that) no substance CHRISTOCRAP is just that

when you use it outside an unsealed reg-component, lexvil

Just ordered a little to try out, my Christo stash is getting low. I’ve been thinking over the last few years that C was designed to go away to support the annual /semiannual thing. It’s a good lube but doesn’t seem to last.

 

[Angelo Farina]

By "hot tune", I assume you mean that it cracks open with barely any effort to breathe at all....right on the cusp of free-flow.

seeing as how I never wanted to waste gas...... I have never understood the appeal to adjust a reg like that and always set mine to be....well I guess you would call it "cold tuned". It has to know that I'm trying to pull a breath.... I don't want my reg confused if I turn my head or look down.....

so I'm very curious whey you want yours as you say "hot"
(or do I not understand what you mean by "hot"?)

When a reg has the knob (as my beloved SP R109s, modified to balanced), I always tune them VERY hot, almost free flowing when looking down, and definitely free flowing if swimming against current. If not, what's the purpose of the knob?
The knob is there so that you normally keep it closed at least one turn. In case of need, you can open it slightly if, for any reason, you need an easier breathing (doing a heavy job, etc.). And you can close it further for other reasons.
A knob which always stays fully open is not very useful.

 

[bradlw]

just seems to me like another failure point OR another something to needlessly putz around with. I'm not talking about setting my regulator so "cold" as to require any real effort to crack it open but so it has some safety margin against wasting gas.... certainly no issue when breathing hard but if it's too cold then yeah it might be a bit noticeable when relaxed and nearly sleeping during a safety stop.

 

[bradlw]

I should add..... and this is based on fuzzy memory about how the things are designed... I do like the idea of unloading the pressure on the seat when the reg is in storage.

 

[Geo7]

Ha ha, I have a tube of this : Krytox™ Performance Lubricants for Oxygen Services
Nice and greasy, clips in easy.
Every sailor knows this [with a candle on the shelf etc etc] 'ditty'.
Such fun.

OK. Knobs, adjustment ones.

I use Krytox GPL205 on the SPG swivel and other places I want to keep water away from, as I was told it is more hydrophobic.

But I took notice of @lexvil's point of making sure the poppet o-rings are well lubricated so it can stay reactive. For everything else I use Tribolube 71 which is for static and dynamic o-rings. Molykote is stickier and might not allow the poppet to react as qickly. Maybe someone knows if that makes a difference?

And to stay on topic: What about corrosion of adjuster knobs in the barrel? Sand and salt getting into the threads can foul them (some reg models expose them more than others). Is it bad enough for some to avoid adjusters? Has anyone found an amazing trick to extend service interval?

 

[Kupu]

Molykote is stickier and might not allow the poppet to react as qickly. Maybe someone knows if that makes a difference?

I use Molykote on most rebuilds, and never had reason to question the performance on balanced poppet orings. With the thought of avoiding excess friction in mind, I lube the poppet orings well and do a bounce test, then put another light application on the orings before final assembly.
It would be interesting to see the results comparing poppet performance using different lubricants, if there was a way to quantify the results.

 

[James79]

I use Molykote on most rebuilds, and never had reason to question the performance on balanced poppet orings. With the thought of avoiding excess friction in mind, I lube the poppet orings well and do a bounce test, then put another light application on the orings before final assembly.
It would be interesting to see the results comparing poppet performance using different lubricants, if there was a way to quantify the results.

Makes me curious if lubing them with silicone oil instead of silicone grease might get a smoother action (but probably at the cost of shorter intervals between needing to re-lube them).

 

[Bigbella]

Makes me curious if lubing them with silicone oil instead of silicone grease might get a smoother action (but probably at the cost of shorter intervals between needing to re-lube them).

I had been instructed, during training years ago, that silicone oil was not to be used on o-rings, depending upon the rubber's composition -- that it would actually cause some natural materials to degrade . . .

 

[BoltSnap]

just seems to me like another failure point OR another something to needlessly putz around with

No to both points. Probably the most popular and most used second stages used, especially in technical diving, have a adjustment knob without any issues in terms of reliability or at least not more so than anything else the diver uses. You don't really putz around with it except when you start your descent or when you reach the surface. I forget that it is there once I start my dive, open all the way.

 

[bradlw]

No to both points. Probably the most popular and most used second stages used, especially in technical diving, have a adjustment knob without any issues in terms of reliability or at least not more so than anything else the diver uses. You don't really putz around with it except when you start your descent or when you reach the surface. I forget that it is there once I start my dive, all the way open.

ahh....nope. Every o-ring, every seat, every moving part is a potential failure point.
but
I get your point....properly engineered, properly maintained, proven to be reliable under harsh conditions beyond the easy recreational, etc....