Hog wrapping a bail out hose under a loop on a rebreather.

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Heat Miser

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Which probably explains why it's taken so long for me to understand that longhose malarkey!
I'm not 100% convinced I understand it except bigger steel tanks good, smaller ally tanks not as good. Harder to donate a single bigger steel tanks when side-mounting with two steel tanks as bailout, so long hose good. Standard config good because muscle memory encourages quick reflex reactions to problems. rEvo / Choptima / Sidewinder non rack configurable because of offboard bailout being sidemounted, but may get you into tighter spaces. Practice with your buddy so as to develop reflexs as per @Dsix36 post.

 

kierentec

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I am sure this has been shared on SB before, but it is my favorite example of how muscle memory can impact performance and the need for consistency. No matter how well you KNOW what the difference in the system is, it’s very difficult to overwrite muscle memory. And then once you do, it’s just as difficult to revert back to the original system:

 

grantctobin

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I'm not 100% convinced I understand it except bigger steel tanks good, smaller ally tanks not as good. Harder to donate a single bigger steel tanks when side-mounting with two steel tanks as bailout, so long hose good. Standard config good because muscle memory encourages quick reflex reactions to problems. rEvo / Choptima / Sidewinder non rack configurable because of offboard bailout being sidemounted, but may get you into tighter spaces. Practice with your buddy so as to develop reflexs as per @Dsix36 post.

or clip the Choptima or Sidewinder to backmount doubles. The Revo is one of a few that can’t really be modified for backmount bailout.


edit: silly multiquote
 

Heat Miser

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or clip the Choptima or Sidewinder to backmount doubles. The Revo is one of a few that can’t really be modified for backmount bailout.
yes ... I'm just trying to understand. Maybe maintain some neuroplasticity. haha...

Apart from the muscle memory issue what is the advantage of manifolded doubles in the above mentioned situation. Surely independent doubles (say side mounted) may be safer? Does the manifold do anything else safety wise. I guess it allows two bailout tanks to feed into the same dil feed for a CCR via the manifold.
 

kierentec

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yes ... I'm just trying to understand. Maybe maintain some neuroplasticity. haha...

Apart from the muscle memory issue what is the advantage of manifolded doubles in the above mentioned situation. Surely independent doubles (say side mounted) may be safer? Does the manifold do anything else safety wise. I guess it allows two bailout tanks to feed into the same dil feed for a CCR via the manifold.
Ease of carrying sufficient gas volumes, if you need 2AL 80s of bottom gas, 50% and o2, it’s a bit cumbersome with everything side mounted, especially off a boat. Throw those 80s on your back and now you just need to carry 2 stages.
 

PfcAJ

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yes ... I'm just trying to understand. Maybe maintain some neuroplasticity. haha...

Apart from the muscle memory issue what is the advantage of manifolded doubles in the above mentioned situation. Surely independent doubles (say side mounted) may be safer? Does the manifold do anything else safety wise. I guess it allows two bailout tanks to feed into the same dil feed for a CCR via the manifold.
The manifold let’s you access the volume of two tanks through one regulator. Can’t do that with independents.

So if you’re OOG, I can give you access to the entirety of my bailout volume in one go.
 

Wibble

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The manifold let’s you access the volume of two tanks through one regulator. Can’t do that with independents.
But... you're then connecting two redundant systems and adding new complexity. Two independent cylinders means that they're completely separate thus cannot have a single failure to kill both (one hopes the soft manifold has a flow restrictor!) and also the benefit of keeping one of the bailouts at full pressure, thus not needing to top off two cylinders at twice the cost of topping off a single. Longhose, no problems, just have two, one going left and one going right.

The sidemount simplicity argument (tips hat in the direction of that crazy UTD sidemount manifold... muscle memory, yeah right!)


So if you’re OOG, I can give you access to the entirety of my bailout volume in one go.
Thought the GUE rig has the diluent shared from the two soft-manifolded cylinders? Diluent's also traditionally used for wing inflation. So not all bailout is available.
 

PfcAJ

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But... you're then connecting two redundant systems and adding new complexity. Two independent cylinders means that they're completely separate thus cannot have a single failure to kill both (one hopes the soft manifold has a flow restrictor!) and also the benefit of keeping one of the bailouts at full pressure, thus not needing to top off two cylinders at twice the cost of topping off a single. Longhose, no problems, just have two, one going left and one going right.

The sidemount simplicity argument (tips hat in the direction of that crazy UTD sidemount manifold... muscle memory, yeah right!)



Thought the GUE rig has the diluent shared from the two soft-manifolded cylinders? Diluent's also traditionally used for wing inflation. So not all bailout is available.
It takes two failures to drain your gas. A leak, and not doing anything about it. The RB manifold is just like a doubles manifold, you can isolate it.

Trimix is always sold by volume. Not sure how you figure topping two tanks with x liters of gas is any more than topping off one tank with the same total liters.

Ew. Metric. Felt dirty to type that.

The dil does come from the bailout, but the amount is very small, and the bailout volume is comparably large.
 

jale

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Hi
To add to the discusion about the GUE config.
For me it makes sense but that doesn't make sense is why they conplicated it by putting the RB between the tanks!
Why not keep the normal OC BM congig and just add a tube RB on the shoulder (Joki style) or SM (Sidekick, Flex, SF1,...)?
With this set up, you don't even need to go out of the loop to give the long hose, the logistic-handling of the tanks-equipment is easier and so on...
 

Wibble

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It takes two failures to drain your gas. A leak, and not doing anything about it. The RB manifold is just like a doubles manifold, you can isolate it.

Trimix is always sold by volume. Not sure how you figure topping two tanks with x liters of gas is any more than topping off one tank with the same total liters.

Ew. Metric. Felt dirty to type that.

The dil does come from the bailout, but the amount is very small, and the bailout volume is comparably large.
Honestly not in for a ruck here... Please educate me...

With a soft manifold there's two valves at each end of the hose. Should the hose rupture:
  • Is the inputs to that hose flow limited though a small orifice in the same way as a SPG connector is?
  • If not, then there's going to be an almighty cloud of gas. If there is then it'll take some time to empty both cylinders.
  • Assume there's loads of drills to shutdown both sides of the manifold.
My point about using one side only was an assumption that the manifolded bailout is also being used by the CCR as diluent and as the wing inflate. For argument's sake say the LH cylinder is connected to dil & wing; this means if you dive with the manifold closed then you'll use, say, 150 litres of dil + wing (5.3 ft3). As the cylinders are 7 litres, this means the pressure drops by about 25 bar (360psi) per dive. Not a lot agreed. But after a couple or three dives it would mean it needs a top-off.

Whenever I buy gas there's a per-cylinder charge as well as a gas volume. There's often an issue with source pressures if there's no booster. Thus filling one cylinder by a "lot" is cheaper than filling two cylinders by a "little".

Probably all heresy anyway! You dive like that as you want to. I don't as I don't. Both of us are right.
 
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