Cavern In Doubles?

[Daedalus]

Would you dive doubles without an isolator? Using that logic suggests you don't need one.

I think the only thing the isolator protects cave divers against is having the burst disk get sheared off or the crossbar gets damaged due to impact with the cieling. These can occur during scootering or rapid travel through confined passage. If you are cautious these things should not be problems, so no I would not have a problem with diving without an isolator.

I think these potential failures could also be eliminated by removing the burst disks from the manifold (as is done on european versions) and coming up with a "one piece" manifold that is stronger than the 3 part assembly we use today.

 

[Meng_Tze]

Are we moving away from doubles at intro to should you dive doubles at all, and if yes, what config?

 

[Meng_Tze]

Hey a quick physics lesson for you, as tanks go into the water and get breathed the outside pressure increases and the inside pressure decreases. If anything is going to blow it is going to blow at the surface.

I don't understand this one.... can you explain?

 

[SparticleBrane]

He's trying to say that as you descend, the outside pressure on the tanks increases and the inside pressure decreases (due to you breathing). Thus comes the idea that o-rings at lower pressures are less likely to blow.
While I would agree that there's less chance of an o-ring blowing at 2400psi rather than 3600psi, at 2400psi there's still plenty of force to push a small piece of rubber through two pieces of metal...


edit:
I'll assume that most people who think o-rings don't blow have never filled their own tanks, or filled a lot of tanks. I'll assume that they've never had to shut down a valve with air spewing out their first stage (or tank neck)...thankfully I've never had to do that in a real scenario, but even doing it in a training situation can make things interesting pretty quickly.

 

[rjack321]

Are single tank intro (or cavern) divers taught back off their allowed 1/3rd even more when diving in a team of 2?

 

[Meng_Tze]

He's trying to say that as you descend, the outside pressure on the tanks increases and the inside pressure decreases (due to you breathing). Thus comes the idea that o-rings at lower pressures are less likely to blow.
While I would agree that there's less chance of an o-ring blowing at 2400psi rather than 3600psi, at 2400psi there's still plenty of force to push a small piece of rubber through two pieces of metal...


edit:
I'll assume that most people who think o-rings don't blow have never filled their own tanks, or filled a lot of tanks. I'll assume that they've never had to shut down a valve with air spewing out their first stage (or tank neck)...thankfully I've never had to do that in a real scenario, but even doing it in a training situation can make things interesting pretty quickly.

I was being facetious....

 

[SparticleBrane]

I was being facetious....

Stupid internet...when can they make it so it can transmit voice inflection too?

 

[WD8CDH]

Would you dive doubles without an isolator? Using that logic suggests you don't need one.

That's a subject that I would really like to see discussed more. Personally, I have seen a lot more dangerous mistakes in the use of the isolator valve than accidents or failures where it would have helped.

 

[Meng_Tze]

That's a subject that I would really like to see discussed more. Personally, I have seen a lot more dangerous mistakes in the use of the isolator valve than accidents or failures where it would have helped.

I guess it was either not taught correctly, the mistakes were because of complacency (not enough practice) or when it was taught no proper attention was given......

When you use them correctly, they can be very safe. And this is not to lead into a isolator vs. independent discussion. But with anything; improper use usually has negative outcomes. And that is part of the discussion on doubles at the cavern/intro levels.

 

[OneBrightGator]

I'll assume that most people who think o-rings don't blow have never filled their own tanks, or filled a lot of tanks. I'll assume that they've never had to shut down a valve with air spewing out their first stage (or tank neck)...thankfully I've never had to do that in a real scenario, but even doing it in a training situation can make things interesting pretty quickly.

I've had to rescue just a few tanks from white water baths when a neck o-ring or burst disk has failed mid-fill. I've never seen an o-ring fail "just because", nor do I see any mechanism for it to.