Necessary to O2 clean 2.stage?

[Rred]

Assuming you are not using your regulator to breath high oxygen concentrations...

Dive shops could help avoid a whole mess of profit, ergh, problems, if they just kept (made) tanks of premix in the shop and gave fills using the premix instead of putting pure oxygen (Boom!) into the tanks and then adding the plain air. Or vice versa. This practice of using pure oxygen, which requires all the cleaning and creates the potential for explosions, is no longer justified by anything except "we have old equipment" or "yeah but that costs more". Yeah, safety always costs more.

But when you are just using standard nitrox blends, ALREADY BLENDED, actually nothing in your gear needs to be "oxygen cleaned". At 32 or 36% oxygen, no special care is needed. All the extra expense on everything is there because the shop is playing with pure oxygen during the fill to create the mix in your tank. And since the second stage in theory is never exposed to pure oxygen...no, it should never need oxygen cleaning. In theory someone could still screw up and get oxygen into it...in theory the sun could go supernova and really ruin your day too. Bigger things to worry about.

 

[the_dragon_no1]

Assuming you are not using your regulator to breath high oxygen concentrations...

Dive shops could help avoid a whole mess of profit, ergh, problems, if they just kept (made) tanks of premix in the shop and gave fills using the premix instead of putting pure oxygen (Boom!) into the tanks and then adding the plain air. Or vice versa. This practice of using pure oxygen, which requires all the cleaning and creates the potential for explosions, is no longer justified by anything except "we have old equipment" or "yeah but that costs more". Yeah, safety always costs more.

But when you are just using standard nitrox blends, ALREADY BLENDED, actually nothing in your gear needs to be "oxygen cleaned". At 32 or 36% oxygen, no special care is needed. All the extra expense on everything is there because the shop is playing with pure oxygen during the fill to create the mix in your tank. And since the second stage in theory is never exposed to pure oxygen...no, it should never need oxygen cleaning. In theory someone could still screw up and get oxygen into it...in theory the sun could go supernova and really ruin your day too. Bigger things to worry about.

Of course, i know anything below 40% don't need special care, that's not what I'm asking about here.

And i asume most consider 40% and up as high, so yeah that's what I'm talking about. (....I mentioned 50% i my first post btw)
So yes, I'll be using 50% nitrox mixes for the stage I'm puting this reg on.

And not that it's really relative to my question, but we mix our own gas at the dive club, and only do partial pressure blending.

Let's keep on track now

 

[Rred]

Sorry, missed the 50% in the fine print.(G)

If you are doing your own mixes and doing 50%...I'd be somewhat frightened that you even have to ask about oxygen problems. A 50% mix is well into the range of "Hey, stuff's gonna set itself on fire."

NASA got a fine surprise when they were designing the Apollo capsules. They used some of that revolutionary new Velcro stuff, figuring it would be a good way to stick things together in the zero-gee capsules. "OOoops." It turns out that Velcro also spontaneously combusts in a high-oxygen environment. Who knew.

Yeah, 50%...bring marshmallows and sticks.(G)

 

[the_dragon_no1]

But let's not forget about the fire triangle now

In a 2nd stage we have oxygen and possible fuel (hydrocarbons), now that's 2 of 3. But we are missing heat.
What would you say is a big possibility for creating that then?
The main sources i belive is the heat of compression and particle impingement (yes there is a few more possibilities.)
But how likely would you say these are in a low pressure 2nd stage (9-10 bar)

 

[nadwidny]

Sorry, missed the 50% in the fine print.(G)

If you are doing your own mixes and doing 50%...I'd be somewhat frightened that you even have to ask about oxygen problems. A 50% mix is well into the range of "Hey, stuff's gonna set itself on fire."

One of the NASA White Sands tests says no.

 

[Rred]

dragon, you forget that most regulators are kept several hundred degrees above absolute zero. IOW, there's already substantial "heat" there. How much heat, or how much heat and other contributors you need at varying percents of oxygen...left as an exercise for those who will be going there.

 

[Centrals]

aww..isn't that sweet. O2 cleaning a second stage is not needed..

I know it is not required but since the Apeks service kit is O2 compatible so why spoil it even for one dive!

 

[tbone1004]

But let's not forget about the fire triangle now

In a 2nd stage we have oxygen and possible fuel (hydrocarbons), now that's 2 of 3. But we are missing heat.
What would you say is a big possibility for creating that then?
The main sources i belive is the heat of compression and particle impingement (yes there is a few more possibilities.)
But how likely would you say these are in a low pressure 2nd stage (9-10 bar)

heat is going to be removed through the pressure drop but gets generated from friction and hitting sharp corners.

@Rred we are only talking about second stages, not firsts/valves/tanks which he said are already O2 clean. I do not know of any O2 incidents related to second stages, and I know that I have quite a few dives with very much not O2 clean second stages, as do all of my dive buddies and they don't have issues. Like I said, many will "o2 clean" them at least in terms of using o2 compatible lube and parts kits because it's more convenient for them to do everything like that. For me, I have enough regulators that I use normal lube and parts kits on everything except for my O2 first stages

 

[Patoux01]

If you are doing your own mixes and doing 50%...I'd be somewhat frightened that you even have to ask about oxygen problems. A 50% mix is well into the range of "Hey, stuff's gonna set itself on fire."

50% on a dirty 2nd stage is gonna set it on fire? We're not talking valves or first stage here.

 

[tbone1004]

50% on a dirty 2nd stage is gonna set it on fire? We're not talking valves or first stage here.

I've never seen or heard of 100% doing it, so couldn't imagine 50% doing it