Alternate Air Inflator & DIR

[Spectre]

It all comes from the big picture. Basic setup is that your right side controls your primary requirements, left side is your secondary requirements. Your primary [wing] inflation comes off the right post, your primary regulator comes off your right post. Your redundant systems off the left post; backup inflation, backup regulator, SPG.

First look at regulators. During your dive when you aren't using the backup regulator but you are still monitoring the integrity of that post because that's where your SPG is coming off of. If you've been keeping track of how much gas you should have based on time and depth during the dive, you should have a good idea of what that SPG will say. If it says something different then it should... you deal with it. If it's too high, it's possible the left post rolled off, or your tanks are isolated.

In an out of air situation, you are donating your primary regulator, on a long hose. When you switch to the backup regulator, you will know if it's off and you will have control to turn it on. If a post is going to roll off from bumping something during a dive, it will be the left post, not the right post. So if it rolls off, you will know. If you were donating to your buddy off the left post, and that post rolled off... they would have to communicate to you to turn that post back on.

So if you were to run an Air2 for your backup instead of a bungied regulator... you'd have to move it to the left post because you have to have what you are donating to your buddy off the right post, and you have to have the two air sources coming off different posts. So now your primary inflation is off your left post, and your secondary inflation gets moved over to the right post.

NOW lets throw in another twist. If a post is to roll off and the valve break so that you can't turn it back on... it's going to be the left post. The right post will roll and break into the 'on' position, not the 'off' position. So if the left post rolls off and breaks off... two things happen. First you loose your primary inflation, since you moved one of your primary systems over to the left post. What else happens? You loose -your- regulator if you are donating gas.

If you are still following along... you'll think "But you loose that secondary regulator when it goes off anyway". Yes, but you actually have 2 sources of gas coming off the primary

post. The regulator that you've donated to your buddy; and your primary inflation. Which has the oral inflation point, and in a pinch will allow you to hold both the inflate and deflate buttons and send gas from the tanks out the oral inflation point... thus giving you a way to breathe.

And of course this is only -one- reason. Other issues could be if you needed to unhook your wing inflation due to an inflator failure; if you need to swap second stages with a stage bottle due to a failure; etc....​

 

[RDP]

Then you're comparing an apple to an orange. They are far from being the same.

MechDiver, I don't understand your last post. These seem to both be apples; their just used in different recipies.

They are both alternate sources of air.
They are both connected to the first stage.
They are both located on the chest near the mouth.

The question I am trying to answer is how they differ when it comes to use in the DIR philosopy. In this respect, this thread has made me think about the following:

The air inflator alternate has questionable function, a shoulder strap, and hose length.
The air inflator has proposes a challenge in bouyancy control while in use.
The DIR style is standard so there is no looking for items in an emergency.
The DIR style has a bungie that can be used to hold the reg in mouth if needed.

 

[RDP]

It all comes from the big picture. Basic setup is that your right side controls your primary requirements, left side is your secondary requirements. Your primary [wing] inflation comes off the right post, your primary regulator comes off your right post. Your redundant systems off the left post; backup inflation, backup regulator, SPG.

First look at regulators. During your dive when you aren't using the backup regulator but you are still monitoring the integrity of that post because that's where your SPG is coming off of. If you've been keeping track of how much gas you should have based on time and depth during the dive, you should have a good idea of what that SPG will say. If it says something different then it should... you deal with it. If it's too high, it's possible the left post rolled off, or your tanks are isolated.

In an out of air situation, you are donating your primary regulator, on a long hose. When you switch to the backup regulator, you will know if it's off and you will have control to turn it on. If a post is going to roll off from bumping something during a dive, it will be the left post, not the right post. So if it rolls off, you will know. If you were donating to your buddy off the left post, and that post rolled off... they would have to communicate to you to turn that post back on.

So if you were to run an Air2 for your backup instead of a bungied regulator... you'd have to move it to the left post because you have to have what you are donating to your buddy off the right post, and you have to have the two air sources coming off different posts. So now your primary inflation is off your left post, and your secondary inflation gets moved over to the right post.

NOW lets throw in another twist. If a post is to roll off and the valve break so that you can't turn it back on... it's going to be the left post. The right post will roll and break into the 'on' position, not the 'off' position. So if the left post rolls off and breaks off... two things happen. First you loose your primary inflation, since you moved one of your primary systems over to the left post. What else happens? You loose -your- regulator if you are donating gas.

If you are still following along... you'll think "But you loose that secondary regulator when it goes off anyway". Yes, but you actually have 2 sources of gas coming off the primary

post. The regulator that you've donated to your buddy; and your primary inflation. Which has the oral inflation point, and in a pinch will allow you to hold both the inflate and deflate buttons and send gas from the tanks out the oral inflation point... thus giving you a way to breathe.

And of course this is only -one- reason. Other issues could be if you needed to unhook your wing inflation due to an inflator failure; if you need to swap second stages with a stage bottle due to a failure; etc....​

I do appreciate the response. I was with you through the first paragraph. After that: up, up, & away..........​

 

[Jason B]

The DIR style has a bungie that can be used to hold the reg in mouth if needed.

The bungie is not to hold it in their mouth.
jason

 

[MechDiver]

I do appreciate the response. I was with you through the first paragraph. After that: up, up, & away..........

A lot of us feel that way about Spectre

I think one of the problems is your perceived idea of how each one of these work, and how they actually work in practice. Hmm, I think that confused me

Anyway, case in point. Person using an alt air was videotaping a scuba class. Concentrating on the camera, he ran into a gill net. Being a somewhat newer diver, he reacted by dropping cam and flailing somewhat. He managed to: knock the reg out of his mouth, get caught in the net, and had both arms severely restrained. Now, his reg was who knows where, his alt air was down at his side, but he couldn't get to it because he couldn't move his arm far enough. Problem?
A necklaced second would have been a good thing in this case.

Also, while we're on the subject, the purpose of the bungie is not to hold the second in your mouth; you do that with your jaw. The purpose of the bungie is to hold the second in front of your face

MD

 

[Spectre]

I do appreciate the response. I was with you through the first paragraph. After that: up, up, & away..........

In that case, let me start by saying... When you understand why the setup is the way it is, you will easily be able to see why changes to that setup isn't optimal.

Now given that you might not accept that, let me step back and try again.

First. Understand everything is designed to be the same as you progress. So if you are diving singles, the issues might not be clear right away; until you move it on to doubles. The same principles will be in effect with the doubles, and most of this stuff is coming from doubles configurations being adapted for use with singles.

Now. In doubles, there is a left and right post, corresponding to the one over your left shoulder, and the one over your right shoulder. If you were to be moving forward and the right valve knob struck something and turned.. it would turn the tank in the on direction... exactly as a single tank valve would turn. However the left post points the opposite direction, so when you roll it along something while travelling forward... that valve will roll into the off position.

Hense the left post will roll off... and the right post will roll on.

Now. If it was to strike something hard enough to roll and break the valve into position.... the left would roll and break off... making it useless.

So because of this, we have our primary equipment routed off the right post, not the left post.

How this applies to your question has to come into the unfortunate event that you have the left post rolling off and breaking... and you -also- have an out of gas situation.

If you remove the regulator from the left post, and use an Air2... you in essence -remove- a source of gas. You don't have 2 sources... you have 3 sources. The primary is your primary regulator. The secondary is your backup regulator. The -emergency- is your wing inflator.

By switching to an air 2, you combine the secondary and emergency systems.

the configuration the way it is provides for two people to breathe off one set of doubles. The donator breathing the regulator on the left post, the donatee breathing the regulator on the right post. It -also- provides for the two people to be breathing off _only_ the right post if the left post breaks. This has the donatee the same, but the donator breathing off the wing inflator mechanism.

The basic point is... You don't need an Air2 type regulator to breathe off of your wing inflation system... you can do it the way it is. So you don't gain anything by having an Air2, but if you remove the secondary regulator around the neck you -lose- something very important.

 

[RDP]

Also, while we're on the subject, the purpose of the bungie is not to hold the second in your mouth; you do that with your jaw. The purpose of the bungie is to hold the second in front of your face

MD

Thanks for your explaination and example. When it comes to the bungie, I thought I read that it can be used to help hold the reg in place if the diver felt they were loosing conciousness? Is this flat out wrong?

 

[RDP]

Thank you, Spectre, for breaking it down for me. I knew you were talking about doubles, but I am not there yet. It was not a pretty sight inside my smoking head. I don't have a problem with DIR. I am just looking to explore the perceived reasoning behind the DIR philosophy.

 

[pete340]

When it comes to the bungie, I thought I read that it can be used to help hold the reg in place if the diver felt they were loosing conciousness? Is this flat out wrong?

http://www.wkpp.org/articles/Gear/newgeorge.html :

"The backup must be instantly accessible. We hang it around the neck on surgical tubing or bungee which is held on by the tie wrap that holds the mouthpiece to the regulator. It must be up close to the neck in order to minimize the venturi effect on the reg, and to provide a strap to hold that reg tightly in the mouth when necessary."

He says the same thing on the GUE "Doing It Right" DVD, while demonstrating how to do it. Then he giggles and says that it doesn't really work.

 

[Boogie711]

Hey Boogie, you want to field this one?

Naw - I'm in therapy now.

I take an Air2 into the backyard and burn it once a week now as part of a spiritual cleansing process. The world is safer because of it too, except for the fumes coming off a burning Air2 are probably toxic.

After all, they'll kill you below water, what's to say they're not deadly above water too?