Cross Bar on doubles?

[PfcAJ]

Darn, I knew that was too good to be true!

How 'bout you shut down the offending post (since manifolds almost never fail) and signal your buddy to take a a look? Its a better use of that 2nd hand

 

[Aquamaniac]

Yeah now tell me that closing the manifold is called isolating...

Which you wouldnt need to do in this scenario

 

[Deep South Divers]

Wow, that exploded quickly.

Aquamaniac, kudos for taking the time to think about this and consider it thoroughly.

Manifolded doubles with isolator manifold -
Advantages
- total redundancy
- all back gas available to all regulators in case of regulator failure
- simplified back gas management
Disadvantage
- increased failure points due to isolator valve turned off, broken, etc

Manifolded doubles with no isoator manifold
-Advantages
- all back gas available to all regulators in case of regulator failure
- decreased failure points due to isolator valve turned off, broken, etc
- simplified back gas management
Disadvantage
- not totally redundant in case of neck seal or disk failure

Independent doubles (actually independent tanks)
-Advantages
- total redundancy
- decreased failure points due to sep valve turned off, broken, etc
Disadvantage
- all back gas not available to all regulators in case of a regulator failure
- you have to manage your gas swapping carefully so not to drain one tank down in case the other fails

Impressive that you'd take the time to work this out. What'd you come up with?

For me, I run an isolator manifold on my doubles - and leave it open all the time. My manifold is the type that has barrel o-rings in it for the most reliability. I also leave the central part of my manifold loose, so that if I bump something, it gives rather than breaking off the valve or handle.

Effectively, it's a "non-isolator" style manifold (never closed) with the ability isolate if I ever need to.

Other than drills, I've never needed to address an isolator failure.

 

[Aquamaniac]

I use both.

I use manifolded twins where-ever possible because of the simplicity of diving them.

I use indy's in a sidemount configuration for many of the cave dives I do here, because of the logistics involved. (tight cave at very remote sites, normally deep into a dry cave). Doubles are out of the question.

No major problems with Indy's, just requires a bit more work and a little more thought.

 

[ucfdiver]

There are 3 valves on the manifold, think again and guess which 2 I meant :shocked2: No one told you before not to put words in people mouths ? Yeah now tell me that closing the manifold is called isolating...

Either way, it's a bad idea. While you're busy shining your light up where your buddy can't see it, he might be swimming away. Losing all your backgas isn't a big deal on a properly planned dive, losing your buddy is.

 

[RJP]

Just curious, did Bam mention he wanted to go cave diving?

...and I'm hope that poster will tell me where the caves are in NJ!

 

[RJP]

Why not leave the isolator almost closed?

Because it's a short trip to "closed" from there.

There are two positions for a valve:

1. all the way opened
2. all the way closed

:cool2:

 

[DA Aquamaster]

I have been teaching tech diving for 8 years and have not yet seen a diver here in cold water who can do a complete valve drill in 10 seconds
More like 30 and on a high performance regulator that equals more like 40-50 cuft.
But no argument with the rest of your post.

He didn't say valve drill in 10 seconds, he said isolate in 10 seconds. In general, woe be the diver who responds to a free flow by performing a full valve drill?

Lol, sure, lets shut down ALL out gas. Shut down both posts with both hands, come on... Its a leak, not the end of the world. Shut down the offending post, see if it can be fixed, and if not, you go home.

Personally, I think it is obvious that a situation where you are losing gas is not the time to do a full valve drill, but I am not sure there is universal agreement on that point.

My approach would be to shut down the offending post if there is an obvious offending post (freeflowing second stage, ruptured hose, etc.).

If there is no immediately offending post, I'll isolate first, then shut down each post individually to see if it is a leaking first stage. You lose little time and gas isolating first in that situation and a first stage leak tends to be much smaller than a ruptured burst disc. So in effect you are hedging your bets and saving gas in anticipation of a burst disc issue rather than first stage issue.

 

[elan]

Darn, I knew that was too good to be true!

How 'bout you shut down the offending post (since manifolds almost never fail) and signal your buddy to take a a look? Its a better use of that 2nd hand

Absolutely. this is what you supposed to do, but my point was that if someone is so paranoid about losing the gas he could even close 2 valves in no time. 1 valve should not even raise any single concern

 

[elan]

Either way, it's a bad idea. While you're busy shining your light up where your buddy can't see it, he might be swimming away. Losing all your backgas isn't a big deal on a properly planned dive, losing your buddy is.

Wow it's amazing how far away people would develop the idea in the direction it was never meant to be taken originally