configuration of gear

[jonnythan]

my wing no can be inflated off my back gas.

:thumbs_up

 

[Soggy]

:thumbs_up

It's been corrected now

 

[BCS]

OK, I have some questions to more expierienced DIR guys.

First - the hypothetical situation but as I understand acceptable by the DIR standarts.

I'm diving wet suit with one tank, two valves. So - on my right valve I have a primary 1st stage, left valve - back up 1st stage.
On the primary I have my primary 2nd stage and wing inflator. On the back up I have back up 2nd stage and manometer.
As I understand this is the proper configuration.
Now imagine that I have a failure of the primary 1st stage. OK, I close my right valve and switch to the back up regulator. But in this case I'm left with no possibility of inflating the wing (except the oral way which is not very efficient and quick). Wouldn't it be better to have the inflator hose on my back up 1st stage instead of the primary? Esspecialy that primary has to do heavier work - both regulator and the wing, which may lead to freezing in cold water. (yeah I do dive the wet suit in the cold water).
So I would like to know your opinion on my dillema - why the only buoyancy device is on the primary 1st stage?
OK I know that in case of the inflator failure I would not be able to close the left valve and at the same time dump air from my wing. But the descripted above situation makes me wonder why it's as it is?
Mania

Hi Mania,
If I'm reading your message correctly, you're asking why the wing inflator on the right post (or in your case...right side of H or Y valve--which goes back to uniformity in configuration from singles to twins). To help illustrate why the wing inflator goes on the right post I'll give a scenario and tell you how it can still be dealt with if the inflator is on the right post....but putting the inflator on the left post does not give the diver in a very bad situation this option.
I'll work backwards from one of the worst possible scenarios in diving and see how we could handle it.
So, we're diving in a cave, tight restriction, single file, and sharing gas. the receiver is on the long hose and the the donor is on the necklace. To make matters worse, the donor rolls off and breaks the left post. The wing inflator can be used as another second stage by depressing both the inflate and deflate button simultaneously and breathing from the oral wing inflate opening. This option is not there if we put the wing inflator on the left. Chances of losing the primary 1st are about the same as losing the backup 1st so that's a moot point arguing over which post to put the inflator based on losing the 1st stage. Oral inflate is always a very easy option anyway. So in deciding which post to put the wing inflate, we go with the one that will give us options in a worst case scenario...albeit, to do this takes some practice and some steady nerves....it nevertheless, is an option I'd like to have available. The other configuration does not give us this option.
Does that help abit with understanding why we do this?

take care and dive safe!---brando

 

[Spectre]

OK I know that with such failure I have to end the dive. What if I have any - even a small one - deco?

Something that may be worth practicing is ending a dive and consciously not using your inflator at all. Get used to the concept that you can ascend without ever adding gas to the wing.

With more confidence, you can disconnect the inflator to keep you honest.

 

[mania]

There is one more thing I want you to answer. Diving in the cold water. The work put on the primary 1st stage is heavier that the back up. That may lead to freezing the primary stage. OK I know it's rare, that mostly 2nd stages get frozen but it may happen. So maybe it's better to put less work on the primary stage?
Sorry for bothering you but as I said - first of all I'm Master in Literature so physics is not the thing I know the best and the second - trying to be convinced and understanding what I'm doing. I have such configuration but I want to know exactly why - instead of simply relying on my guys here who are DIR or Hogarthian
Mania

 

[Spectre]

I've never had any problems.

You can always inflate when you're exhaling

 

[jonnythan]

There is one more thing I want you to answer. Diving in the cold water. The work put on the primary 1st stage is heavier that the back up. That may lead to freezing the primary stage. OK I know it's rare, that mostly 2nd stages get frozen but it may happen. So maybe it's better to put less work on the primary stage?
Sorry for bothering you but as I said - first of all I'm Master in Literature so physics is not the thing I know the best and the second - trying to be convinced and understanding what I'm doing. I have such configuration but I want to know exactly why - instead of simply relying on my guys here who are DIR or Hogarthian
Mania

Like Spec said, I've heard of people waiting until they're exhaling to inflate to lessen the cooling effect on the first stage. Use the right first stage and it shouldn't matter though

 

[Spectre]

Ok. The serious answer.

It's exactly as Brando stated.... it had to do with uniformity between singles and doubles. Yes, perhaps you limit a little bit of a freezing risk by moving the inflator to lessen the work on the reg. Of course when you are diving in water cold enough that freezing is a risk, you would be [or should be] in a drysuit; and thus you have you're redundancy there.

As far as why the doubles are setup the way they are, there are a number of threads about that [and left post rolloff and all that].

Edit: Actually with H valves, the benefit of having the inflator on the same reg as the long hose is similiar to the doubles scenario. If you have to turn off the left post [the non-donatable reg] you still have a donatable reg and a gas source for yourself. [as Brando described above]

 

[Soggy]

There is one more thing I want you to answer. Diving in the cold water. The work put on the primary 1st stage is heavier that the back up. That may lead to freezing the primary stage. OK I know it's rare, that mostly 2nd stages get frozen but it may happen. So maybe it's better to put less work on the primary stage?

In dives down to 37 degrees, I've never had a freezing issue with either my SP Mk25 or Apeks DS4s. You are right, there is the possibility for a potential issue, but the benefits far outweigh the drawbacks. Besides...you have 2 first stages, don't you?

 

[BCS]

There is one more thing I want you to answer. Diving in the cold water. The work put on the primary 1st stage is heavier that the back up. That may lead to freezing the primary stage. OK I know it's rare, that mostly 2nd stages get frozen but it may happen. So maybe it's better to put less work on the primary stage?
Sorry for bothering you but as I said - first of all I'm Master in Literature so physics is not the thing I know the best and the second - trying to be convinced and understanding what I'm doing. I have such configuration but I want to know exactly why - instead of simply relying on my guys here who are DIR or Hogarthian
Mania

Hi Mania,
If you're speaking to me, you are no bother at all and I hope I'm able to help answer some of your questions. I am sure there are others who have the same questions and appreciate the info as well.
While certainly the added use of the primary 1st stage will contribute to the possibility of a free flow, my experience (at least my own--and I'm sure there are those that dive in water colder than the Great Lakes that will agree) shows that risk to be negligible and easily managed should it ever happen.
Also, think about this...if we do use your logic, that is put the inflator on the backup reg 1st stage, and now the backup reg is being taxed....when would you want a free flow...when your are on your primary and can easily shut it down and go to your back up, or when you are on your backup (ie. sharing gas) and cannot shut it down (because it is now your gas supply)? I'll take managing the free flow while I have something to go to and stress levels are significantly lower.
Does that make sense?
Hope that helps a bit!

take care and dive safe!---brando