Which post for DIR?

[WYDT]

Originally posted by Rick Murchison

But Rob,
In your first scenario you only have to check for a roll-off once...
Rick

hehe... yeah but not EVERYONE makes sure they can reach their valves... :mean:

Just pointing out that it could be confusing to introduce another set of valves that are different than the current and not everyone would be aware... heck, I still have seen guys that hook the fill whip up to BOTH valves on my doubles to make sure they fill both tanks... That was funny!

liability plays a B I G part in this game and it doesn't always make perfect sense.

DSAO!!

 

[WreckWriter]

Originally posted by WYDT
heck, I still have seen guys that hook the fill whip up to BOTH valves on my doubles to make sure they fill both tanks... That was funny!

Around here most fill jockeys seem to do that......

Tom

 

[VTWarrenG]

The left-handed valve idea sounds good to me, I'll be honest.

Tank valves (even special left-handed ones) don't cost all that much anyway.

- Warren

 

[The Chairman]

Pardon my ignorance... I thought this was the proper protocol for the partial pressure filling of doubles? Am I in error here? Even if you were merely "topping" off tanks, I would think it would be a good habit to be in. I don't believe that agitation alone would mix the two tanks through such a small orifice.

Also, for what it's worth (not much, I know), the left hand threaded valve seems like a great idea -IF- it was only used as the left side of a doubles set-up. Think of the confusion if the tanks were seperated for use as singles. It would be like getting one of those birthday cards that open the wrong way, only not near as funny! I would be hesitant to purchase anything that might have such dire consequences.

 

[WYDT]

Originally posted by NetDoc
Pardon my ignorance... I thought this was the proper protocol for the partial pressure filling of doubles? Am I in error here? Even if you were merely "topping" off tanks, I would think it would be a good habit to be in. I don't believe that agitation alone would mix the two tanks through such a small orifice.

Nope, you fill through one valve and as long as the isolator is OPEN the gas mixes just fine. There's no way more O2 (or He, or air) will go in one tank than the other just because you're filling from one valve or the other. It seeks equalibrium and very quickly.

You'll never find anyone who actually knows what they are doing fill any other way.

DSAO!

 

[VTWarrenG]

Remember that tanks and valves can be sold separately.

NetDoc, the number of folks routinely breaking apart doubles to dive them as singles is, from my experience, very small. Besides, if you're smart enough to set up and tear down a set of doubles, you're probably smart enough to use a "backwards" valve.

If a given manufacturer made left-handed DIN valves, it would only be a slight additional expense to include one in a set of doubles.

Are we all missing some glaringly huge drawback, or is this really an honest-to-god good idea?

Who wants to be the guinea pig to post on techdiver?

- Warren

 

[Aviatrr]

Are we all missing some glaringly huge drawback, or is this really an honest-to-god good idea?

You're missing a very big drawback......teachers know it as the law of primacy....most people know it as the old adage old habits die hard. During a stressful situation, people generally revert to their initial training......which means that most people would likely, regardless of what they tell themselves or others, try to turn the valve the wrong way.

Seems to me that people are just trying to re-invent the wheel here.

Mike

 

[Rick Murchison]

Originally posted by Aviatrr


You're missing a very big drawback......teachers know it as the law of primacy....most people know it as the old adage old habits die hard. During a stressful situation, people generally revert to their initial training......which means that most people would likely, regardless of what they tell themselves or others, try to turn the valve the wrong way.

Seems to me that people are just trying to re-invent the wheel here.

Mike

This argument has been used against every change made in cave diving since its beginning. Would you believe there were serious arguments against SPG's, safe seconds, redundant regs, isolation manifolds... you name it. They were all opposed, often vehemently. Often by "big names."
The fact is that the current arrangement has an unnecessary hazard in that the left valve can be easily rolled off, and in fact has been a factor in more than one fatality. It needs fixing, and "habit" isn't a sufficient reason to deny it.
In my career as a professional naval aviator I had to learn new emergency procedures every time I changed airplanes - and sometimes had to keep 'em separate for two different airplanes I was flying at the same command - and, the procedures for one could kill you in the other. Keeping it all straight was absolutely essential to survival - and we did it. That's why I can say with absolute confidence that for me, I can train myself to respond with "forward off" on both valves with five minutes practice and zero chance of screwing it up. You can too.
Rick

 

[Aviatrr]

This argument has been used against every change made in cave diving since its beginning. Would you believe there were serious arguments against SPG's, safe seconds, redundant regs, isolation manifolds...

One slight difference.....those things were all new equipment, not internal changes to existing equipment that would remain the same in physical appearance and feel.

In my career as a professional naval aviator I had to learn new emergency procedures every time I changed airplanes - and sometimes had to keep 'em separate for two different airplanes I was flying at the same command - and, the procedures for one could kill you in the other. Keeping it all straight was absolutely essential to survival - and we did it.

I understand that, and I have to deal with the same issues. The difference is the visual cues. Each cockpit of a different type of aircraft is unique. Switches, levers, controls, etc. are in different locations.

That's why I can say with absolute confidence that for me, I can train myself to respond with "forward off" on both valves with five minutes practice and zero chance of screwing it up. You can too.

While I agree that such would be the case with many, if not most, people, there would be problems. It WOULD eventually contribute to a death, maybe two.

Why not call some of the manufacturers and ask them for their input, and ask if they ever have or would produce such a valve? I'd be interested in hearing what they have to say. Maybe try calling Lamar at Dive Rite and ask him about it.

Mike

 

[CincyBengalsFan]

Whoever posted that the person that is out of air can not tell the donor the left post rolled off is a GREAT person. NOW, that is a reason not to put it on that post. THANKYOU for that reply. That is all I wanted. Also...I'm glad there are so many supporters for the threads to be reversed on the left post. I talk with the manufactures several times a week and will relay this response on to them. Thanks again.