40% O2 mix at the safety stop

[Flightlead]

Not in most parts of the world.



Not in most parts of the world.



Proper labelling with name and MOD.

not that I'm recommending it but....just go to the the welding gas suppliers. I used to be able to buy welding, medical, and aviators o2 grade there and no one gave a damn about anything other than the stickers on the tank. may have changed since 9/11 but I doubt it.

 

[Blackwood]

I used V-Planner for the comparison with 40, 50 and 100% and I found 50% is shorter with trimix. Maybe 70% is shorter with air.

It depends on the profile. If there isn't enough gradient between your the bottom and your deco level, you'll be relying on oxygen vacancy alone.

Go run something like 80 for 80. I'm betting decoing on O₂ will get you out of the water faster than EAN50.

 

[Thalassamania]

I think you're overestimating the difficulty and over-dramatizing the situation.

Sure with two travel mixes, bottom mix and two deco mixes you'd have a point. But coming up to 20 feet and switching to either a hang bottle or a pony hardly requires a drum roll.

Ta-da!

 

[String]

not that I'm recommending it but....just go to the the welding gas suppliers. I used to be able to buy welding, medical, and aviators o2 grade there and no one gave a damn about anything other than the stickers on the tank. may have changed since 9/11 but I doubt it.

Many people use welding grade O2 here - its cheaper than diving and prepared in exactly the same way. The only difference is less of a paper trail.

 

[Flightlead]

Medical O2 i think has a higher moisture content and maybe a tiny bit of CO2 whereas diving doesnt.

We use the same stuff here for diving and O2 first aid though (100% pure o2) which any dive shop can get.

last I spoke to the suppliers, which I admit has been 6 or7 years I was told "it all comes from the same tap". There are some differences in allowable moisture content in the breathing grades, but I was told its cheaper to manufacture all to the highest standard than to have two manufacturing lines, manage two sets of storage, etc etc.

the difference, I was told, between breathing grade and welding grade is the handling of the bottles. ie whether or not the bottle is drawn down to a vacuum before refilling or not.

I regularly breathed welding oxygen when cruising in the low flight levels, but I owned the bottle and controlled what went into it.

 

[Thalassamania]

It all comes from the same cooling column. Medical grade oxygen must have the cylinder evacuated prior to filling, welding gas is just, "fill'er-up."

 

[nereas]

I was under the understanding that medical 02 bottles had a different regulator/first stage connection and most dive shops did not have this fitting.??

Med O2 bottles and DAN O2 bottles have the same fittings.

Thus, dive shops are able to full both.

 

[nereas]

...
... why?

What if I'm in San Diego diving the Yukon. Say an hour at 90 feet. For that profile, O₂ makes perfect sense, and personally I'd rather have it with me (i.e. slung) than leave it somewhere I may not be able to return to.

For the sake of brevity, just remember that if you are bringing only one deco bottle, then make sure it is EAN 50 and not 100% O2.

Then you will likely live longer and prosper.

You can make this your personal Rule #2.

 

[Bismark]

For the sake of brevity, just remember that if you are bringing only one deco bottle, then make sure it is EAN 50 and not 100% O2.

Then you will likely live longer and prosper.

You can make this your personal Rule #2.

I might be missing something here. Why are you saying this? what would you be doing exactly with your 50% bottle after 60 minutes at 90'?

 

[String]

For the sake of brevity, just remember that if you are bringing only one deco bottle, then make sure it is EAN 50 and not 100% O2.

Why ?! 100% O2 on that profile makes perfect sense. You need to take less O2 than 50 and would be out of the water faster.