Certification Needed For pure O2????

[rx7diver]

Helter Skelter,

If you search "explosion" in the Accidents forum, you'll see several threads that should be of interest to anyone considering working with scuba cylinders containing pure oxygen. This one (http://www.scubaboard.com/forums/ac...10-o2-tank-explosion.html?highlight=explosion) and another one involving a pickup truck, shaped my thinking about whether I want to have oxygen scuba cylinders around if they're not absolutely necessary.

Safe Diving,

rx7diver

And here is the second thread: http://www.scubaboard.com/forums/ac...deco-cylinder-mishap.html?highlight=explosion.

 

[uncfnp]

What cert would I need to carry a O2 pony bottle and more importantly Be able to get it filled? I read where some divers breath O2 at the safety stops and they swear by it. And no not just deco divers mentioned this. although deco diving is something I want more info on.

Thanks
Scott

If you are serious about wanting deco too, then go for the AN/DP course. Much smoother to take them together. Otherwise just get your Advamced Nitrox certification. It will give you the card and the facts needed to get O2 and use it safely. But it's a real hassle carrying that extra bottle on routine recreational dives. There would need to be a significant benefit to hassle to put up with the inconvience.

And make sure you label the tank in bold letters warning others off, that it is NOT a pony to be share at depth for OOG divers.

 

[The Chairman]

And make sure you label the tank in bold letters warning others off, that it is NOT a pony to be share at depth for OOG divers.

Word!

 

[Patoux01]

And make sure you label the tank in bold letters warning others off, that it is NOT a pony to be share at depth for OOG divers.

Hmm a diver shouldn't grab at you for anything, if he grabs the wrong thing, correct him. If he doesn't want to change regs for something breathable, well, Darwin is there for him.

Not saying I'm not labelling tanks when they might be brought with me above their mod, but I don't think the kind of divers that would grab a pony bottle would realise that the huge "21" on my tank would mean "do not use below 21meters". But I guess we just have a different view on the role of the MOD stickers. I see them as a warning from me to myself to not be retarded, you seem to see them as a warning for others

 

[KenGordon]

Hmm a diver shouldn't grab at you for anything, if he grabs the wrong thing, correct him. If he doesn't want to change regs for something breathable, well, Darwin is there for him.

Some agencies teach secondary take. When OOG you take the octopus rather than waiting for the other diver to notice the OOG signal. To give them a chance to take the correct reg you should have stuff properly labelled, turned off etc.

---------- Post added May 6th, 2015 at 06:39 AM ----------

Not saying I'm not labelling tanks when they might be brought with me above their mod, but I don't think the kind of divers that would grab a pony bottle would realise that the huge "21" on my tank would mean "do not use below 21meters". But I guess we just have a different view on the role of the MOD stickers. I see them as a warning from me to myself to not be retarded, you seem to see them as a warning for others

Aren't they there so your buddy can stop you using a gas past its MOD?

 

[Searcaigh]

Not saying I'm not labelling tanks when they might be brought with me above their mod, but I don't think the kind of divers that would grab a pony bottle would realise that the huge "21" on my tank would mean "do not use below 21meters". But I guess we just have a different view on the role of the MOD stickers. I see them as a warning from me to myself to not be retarded, you seem to see them as a warning for others

Which is why we take courses in using gas mixes other than air and standard Nitrox

 

[Lorenzoid]

Is there a way to quantify the relative offgassing benefit of doing a safety stop on O2 versus doing a longer safety stop on air (or Nitrox)? Is it possible to determine the number of minutes one would need to remain on, say, air at 15 feet to get the same offgassing (I hesitate to say "decompression") benefit as one would get from a 3-minute stop on O2? Assuming some typical recreational "no stop" profile, of course.

---------- Post added May 6th, 2015 at 08:54 AM ----------

And make sure you label the tank in bold letters warning others off, that it is NOT a pony to be share at depth for OOG divers.

Interesting point. Divers who carry O2 for deco are not typically diving in a mixed group with recreational divers who may have never seen a deco bottle before.

 

[Basking Ridge Diver]

Is there a way to quantify the relative offgassing benefit of doing a safety stop on O2 versus doing a longer safety stop on air (or Nitrox)? Is it possible to determine the number of minutes one would need to remain on, say, air at 15 feet to get the same offgassing (I hesitate to say "decompression") benefit as one would get from a 3-minute stop on O2? Assuming some typical recreational "no stop" profile, of course.

For Deco projections you can use V-Planner just to play with 50%, 75% or 100% or any % you care to use including 21% as a baseline. I have played with being on the NDL and increasing conservationism which will give you deco time - then you can use different gases on your deco stop as a tool to understand how it impacts your deco.

Within NDLs I have no idea how you prove or disprove O2 benefits...

 

[kr2y5]

Within NDLs I have no idea how you prove or disprove O2 benefits...

I'd just look at surfacing GFs. For example, PADI tables seem to be allowing 20 minute NDL for a dive to 100 feet on air. Unless I punched the wrong buttons, to make this nominally "NDL", I have to specify surfacing GF of 100 in my planning software. If you want to be more conservative, say surfacing GF of 80, which seems like a popular value, there would be a a little under a 3-minute stop on O2 at 20 feet. If you don't carry O2, the 20-foot stop will extend to almost 7 minutes. I think in general for various recreational profiles and GF settings, it typically saves more than 50% of the deco time.

 

[victorzamora]

Is there a way to quantify the relative offgassing benefit of doing a safety stop on O2 versus doing a longer safety stop on air (or Nitrox)?

As was said before, use V-Planner or PastoDeco to plan a bunch of dives (you have to force in a safety stop as an additional level). Then, look at GF-exit. This will tell you, according to Buhlmann ZHL-16, what "percentage" of theoretical bendiness you're at. For example, 30/80 GFs give you a surface GF of 80....which puts you at 80% of the pressure gradient of "some bent." I know that sounds crazy, and this all goes back to the whole "measure with micrometer, mark with chalk, cut with axe" adage.....your surfacing Gradient Factor is the theoretical bendiness, and is a quantifiable measure.

However, I'll give you this rule of thumb: O2 is a bit better than double of air, and a bit under double of EAN32. So a 5min safety stop on O2 is about 12min on air and 8min on EAN32 (rough ballpark figures).

---------- Post added May 6th, 2015 at 10:35 AM ----------

there would be a a little under a 3-minute stop on O2 at 20 feet. If you don't carry O2, the 20-foot stop will extend to almost 7 minutes. I think in general for various recreational profiles and GF settings, it typically saves more than 50% of the deco time.

3min on O2 vs 7 on air....that's about right. I'd bet it'd be 5min if EAN32 were available....kind of validating my rough rule.