Two 2nd stages, but only a single first stage?!?

[toliver66]

This thread brings to mind a question I've always wondered about. It is possible to breath straight off of a tank valve by just cracking it open just like you would breath from a free flowing reg in the event of a total regulator failure. This is just an option that pops into my head every time I hear someone talk about an OOA situation due to catastrophic 1st stage failure. But realistically speaking... just how likely is it that any one would/could pull this off successfully? Remove your BC, tank, harness... what ever, then remove the first stage from the tank and breath from a free flowing tank valve?

 

[Paulmal]

It used to be part of open water training to breath straight from a tank valve but the was many moons ago.

 

[AaronRiot]

The Mythbusters need more scuba related episodes. Lol.

 

[cbrich]

This thread brings to mind a question I've always wondered about. It is possible to breath straight off of a tank valve by just cracking it open just like you would breath from a free flowing reg in the event of a total regulator failure. This is just an option that pops into my head every time I hear someone talk about an OOA situation due to catastrophic 1st stage failure. But realistically speaking... just how likely is it that any one would/could pull this off successfully? Remove your BC, tank, harness... what ever, then remove the first stage from the tank and breath from a free flowing tank valve?

It was done in the move Sanctum, and also on oxygen. I would not want to try it.

 

[Paulmal]

It was done in the move Sanctum, and also on oxygen. I would not want to try it.

Yea the kid should have ox-toxed as he was deeper than 20 feet for several minutes but hey they can do anything in the movies. Keep in mind that it takes approximentaly 2 minutes for a gas to fully saturate your lungs after a gas switch and everyone can handle diffrence levels of oxygen exposure but you can only be on O2 so long at 70' before you start to have symptoms.

 

[DA Aquamaster]

It used to be part of open water training to breath straight from a tank valve but the was many moons ago.

We did it in 1985, but it was recognized as an "old school" skill even then.

---------- Post Merged at 03:24 PM ---------- Previous Post was at 03:16 PM ----------

Yea the kid should have ox-toxed as he was deeper than 20 feet for several minutes but hey they can do anything in the movies. Keep in mind that it takes approximentaly 2 minutes for a gas to fully saturate your lungs after a gas switch and everyone can handle diffrence levels of oxygen exposure but you can only be on O2 so long at 70' before you start to have symptoms.

Especially if you are exerting your self.

However this is the same kid with the 10W LED tooth light and when busy not toxing at extreme PO2s he was breathing out of air pockets on the cave ceiling (which would not have been there anyway - but whatever...

 

[drbill]

In 50 years of diving, I've never had a second stage fail to the point I couldn't breathe from it. Even the one I accidentally smashed under my tank when filling it still functioned. I have had first stages fail... twice underwater and twice as I pressurized the reg before descending. I have also had the dip tube in a K-valve clog so no air was getting to the reg's first stage at all. Not sure if the H-valves have dual dip tubes and air pathways or not.

These are reasons why I dive with a totally redundant air supply (pony).

 

[houe]

In 50 years of diving, I've never had a second stage fail to the point I couldn't breathe from it. Even the one I accidentally smashed under my tank when filling it still functioned. I have had first stages fail... twice underwater and twice as I pressurized the reg before descending. I have also had the dip tube in a K-valve clog so no air was getting to the reg's first stage at all. Not sure if the H-valves have dual dip tubes and air pathways or not.

These are reasons why I dive with a totally redundant air supply (pony).

I believe I am going to go with a pony. Been reading up and it sounds like a mk2/r295 would be a good choice for the pony. It doesn't necessarily have to breath better than my primary (Atomic), but it does need to be as reliable. I hear good things about the mk2/r295 combo for this purpose. I think i'll probably do a 13cf pony attached to my tank. Question: In this situation does a person need a AAS for the main tank or does the pony suffice? An option would be to have a AIR2 type regulator without adding extra hoses - I don't want to get too complicated.

 

[GrumpyOldGuy]

If your diving solo, the extra 2nd is not need. 13 cu ft is enough for you to ascend, with no extra for fooling around.

Add the possibility of an OOG buddy sharing your pony which is attached to you and the flexibility of having dual access to your main tank is a nice option. As you go up in pony sizes to 19+, its not such a big issue, but 13 has no margin for additional errors in an already bad situation.

 

[houe]

I will not be diving solo. I will have a buddy. The pony is just in case the ship hits the dam.