Doubles?

[firemedic8082]

Maybe a dumb question but here goes: If you have a failure in 1 of your first stages on a set of doubles and have to shut that tank, do you still have access to the gas in that tank from the other side or is the tank with the OOS reg isolated from the working side??

 

[Jimmer]

Yes. When you shut down the "post" of the offending reg, all you are doing is shutting down the "outlet" so to speak, that feeds that reg. So the other side will still have access to the gas in that tank. If the failure is something like a burst disk or neck o-ring, you have to isolate the two tanks, and you will only have access to the one tank now.

 

[ltw123]

If you have problems with a reg (1st or 2nd stage), you can shut down that valve/post (not the isolator) and still have access to your entire gas supply with the other regulator.

If you blow a burst disk or o ring, then you will have to shut the isolator (the knob in the middle). Now you only have access to the isolated Ž½ of your gas through whichever regulator is attached to that side©Ñlus that which is bubbling away very quickly on the other side (not much).

Some isolate then go to the post when they hear bubbles, then possibly back to open the isolator, others go the post first and then isolate only if necessary.

If shutting down the post solves your problem, then youÃÍl have access to all your remaining gas through the other regulator (isolator must be open). If you have to isolate, then youÃÍl only have access to the gas in the cylinder on the functioning side of the isolator.

Hope this makes since©Ïow IÃÎ a little confuses???

 

[Captain12Pk]

Yes. You will continue to have access to the gas in both tanks as long as you do not shut down your isolator.

 

[firemedic8082]

Thanks for the clarification guys.

 

[super7]

All the answers are there. But to know where you're leaking, you'll need to do some thinking.
The way I learnt it,
1) Isolator valve shuts first.
2) Look at your SPG.
3) SPG reading going down means failure in your left hand side, not going down means failure in your right.
4) Shut down the valve on the side deemed leaking.
5) If you've stopped leaking air, reopen the isolator, not the valve, and make use of all the air in both tanks through the unaffected reg. If not, don't reopen the isolator, or you'll lose air from both tanks.

IMO, going for the isolator first makes sense. Makes diagnosis easier for a novice like me, and should reduce the amount of gas lost.

If you're still leaking air, keep the isolator shut, reopen the broken side valve, and use all air available from that side first. This part, my two yen

 

[DA Aquamaster]

The above response will be the subject of some debate.

Some agencies, that I shall leave nameless, teach shutting down the post on the reg you are currently breathing first as statistically that is the reg most likely to fail. You then breathe the reg down and if the bubbles stop, the leak is in that reg. If not, you turn it back on and turn the other post off and breathe that reg down. If the bubbles stop this time, the leak is in that reg. If the bubbles do not stop, you close the isolator as the leak is in the manifold, burst discs or neck o-rings of the tank.

The problem with the above method in my opinion is that it works fine for small pleasantly bubbly sorts of leaks that pose no immediate threat of catatrophic gas loss. But for large leaks, you are going to waste an awful lot of gas before you get around to isolating and given that a ruptured busrt disc can empty a full set of doubles in about 3 minutes, you are potentially losing 1/3rd of your gas every minute and you may not have the gas to lose if the failure occurs at max penetration where you used 1/3rd getting there and will lose another third automatically in the tank with the ruptured disc or extruded neck o-ring. In that case, one half of the gas you loose before you isolate comes out of the only 1/3 you have left to get out of the overhead, so the sooner you isolate the better.

So for small leaks I shut down the posts in order to diagnose where it is at, for large leaks I isolate as soon as humanly possible to ensure I have a third of my gas left to exit, then shut down the posts in sequence.

Obviously if the leak is evident - as in the gas is coming out a second stage, I just shut down that post.

 

[Rick Inman]

If it's more than a "pleasantly bubbly sort of leak", my buddy will also be motivated to diagnose and shut down if I'm not sure where the leak is. My gas is his gas.

 

[Rick Murchison]

First of all, the most common leak requiring a shutdown is a freeflow - in which case you (obviously) just shut down that post and breathe off the other reg...
Likewise for any other "up-front" leaks - SPG, BC inflator, Dry suit valve, burst hose you can see, etc...
For a mystery leak - one you can hear but not see:

(1) Catastrophic leak - a sudden BIG leak (if a BIG leak isn't sudden you'll have already taken care of it before it gets big ) - Shut down all three valves.
(1.a) Leak continues - leak is either burst disk or tank o-ring or somewhere in the manifold - leave isolator closed, open both tank valves. Determine which side is leaking, breathe off the leaking tank until it is exhausted, then switch to the other tank; abort dive.
(1.b) Leak stops - leak is at first stage or beyond. Open primary valve.
(1.b.1) Leak resumes - shut down primary valve, open secondary valve and breathe off secondary reg; open isolator; abort dive.
(1.b.2) Leak doesn't resume - breathe off primary; open isolator; abort dive

(2) Leak smaller than catastrophic but more than "minor irritant" - shut down primary reg; breathe it down
(2.a) Leak stops - switch to secondary reg; abort dive
(2.b) Leak continues - open primary reg, shut down secondary, switch to secondary, breathe it down
(2.b.1) Leak stops - switch to primary reg; abort dive
(2.b.2) Leak continues - open secondary valve; isolate; determine which side's leaking, breathe that tank 'til depleted, switch to other tank; abort dive

(3) "Minor irritant" leak - be prepared to handle condition (1) or (2); abort decision depends on the dive.

The preferred team approach to a catastrophic leak on your buddy's system is to hand your buddy your primary while you do all the valve stuff.
If your buddy does that for you, great, but be prepared to do it all yourself.

Rick

 

[texdiveguy]

First of all, the most common leak requiring a shutdown is a freeflow - in which case you (obviously) just shut down that post and breathe off the other reg...
Likewise for any other "up-front" leaks - SPG, BC inflator, Dry suit valve, burst hose you can see, etc...
For a mystery leak - one you can hear but not see:

(1) Catastrophic leak - a sudden BIG leak (if a BIG leak isn't sudden you'll have already taken care of it before it gets big ) - Shut down all three valves.
(1.a) Leak continues - leak is either burst disk or tank o-ring or somewhere in the manifold - leave isolator closed, open both tank valves. Determine which side is leaking, breathe off the leaking tank until it is exhausted, then switch to the other tank; abort dive.
(1.b) Leak stops - leak is at first stage or beyond. Open primary valve.
(1.b.1) Leak resumes - shut down primary valve, open secondary valve and breathe off secondary reg; open isolator; abort dive.
(1.b.2) Leak doesn't resume - breathe off primary; open isolator; abort dive

(2) Leak smaller than catastrophic but more than "minor irritant" - shut down primary reg; breathe it down
(2.a) Leak stops - switch to secondary reg; abort dive
(2.b) Leak continues - open primary reg, shut down secondary, switch to secondary, breathe it down
(2.b.1) Leak stops - switch to primary reg; abort dive
(2.b.2) Leak continues - open secondary valve; isolate; determine which side's leaking, breathe that tank 'til depleted, switch to other tank; abort dive

(3) "Minor irritant" leak - be prepared to handle condition (1) or (2); abort decision depends on the dive.

The preferred team approach to a catastrophic leak on your buddy's system is to hand your buddy your primary while you do all the valve stuff.
If your buddy does that for you, great, but be prepared to do it all yourself.

Rick

What he say....................can you repeat that.