Single Tank Valve Drill

[Kevrumbo]

Sure, assuming your Dive Ops at your tropical destination has an H or Y valve DIN set-up . . .Y'all bring your own to install, huh?

 

[PfcAJ]

Just as with anything, H and Y have their place. I do not advocate deco/deep >100ft/cave diving in a single, H or not.

People who see it nesessary to have separate first stages can find benefit with an H valve. Its an optional piece, not a big deal in the grand scheme of all things DIR.

There is some difference and discrepancy even among GUE instructors. Even through our standardization, variance exists. This is what makes DIR an evolving system.

 

[LVX]

I usually refer to this article when discussing issue of H and Y valves:
http://www.dir-diver.com/en/knowledge/single_hvalve_doubles.html

Here is what is posted on the website you listed.

Another drawback to using two first stages on a single tank is complexity. You need to be as familiar with your configuration as a double tank diver but also you need to be able to reach back and operate your valves because if you can't shut it down you have gained nothing. H-valves and Y-valves are often difficult to reach and the configuration is not streamlined and neat because you have to much regulator and not enough room.

Another reason why some want to use an H-valve is so that they can use the same setup for their doubles. Besides the very busy configuration you also get the wrong hose lengths because these have to fit you doubles where the first stages are located on each tank and not in the middle. So while it might work it is not optimal.
------------------------

I have been using an H-valve for any dives shallower than 100 ft for several years now. Over that I use doubles. I have never had a routing problem and I can reach my valves. I personally do not see a problem with it. And yes, everything is streamlined.

As the article points out however, I would not use a single tank at all for anything complex or anything that requires deco.

Just my 2 cents...

 

[coldsmoke]

Thanks for all of the replys. I failed to specify that my question was in reference to a single valve set up. Not with an H valve (technically don't know if it's considered one or two valves but I think you all understand what I mean). The thing that I was having trouble understanding is when would you ever need to shut down your only valve. As mentioned above I can understand the merit in being able to turn your valve on if it some how gets shut off, but shouldn't your pre-dive sequence prevent you from entering with a closed valve? If you have catastroohic valve or regulator failure then you lose your air - so what. If you turn off your valve then you can't breath it anyway.

I am not saying that it's bad to practice it - I'm a rookie after all and certainly not qualified to make such statements. And I think anything that promotes comfort and confidence in your equipment and ability is worth while, but is there any real world scenario where you would even need or want to do it?

 

[WJL]

s there any real world scenario where you would even need or want to do it?

Yes.

Scenario 1. You do your pre-dive checks and confirm your valve is open. While you are standing at the stern getting ready to jump in, a helpful boat worker shuts your valve down without you knowing it, thinking he is opening it. You jump in with a closed valve. This has happened more than once in the real world.

Scenario 2. You do your pre-dive checks and open your valve. However, today is a bad day and by mistake you actually close down your valve, leaving it open just a fraction of a turn. It breathes fine on the surface. You jump in with a mostly closed valve. At 50 feet deep you can't get a breath from your regulator. This has happened more than once in the real world.

If you think there will never be any mistakes, you are making a mistake.

 

[MonkSeal]

I am not saying that it's bad to practice it - I'm a rookie after all and certainly not qualified to make such statements. And I think anything that promotes comfort and confidence in your equipment and ability is worth while, but is there any real world scenario where you would even need or want to do it?

I'll give you few scenarios:
1. Fixable 1st stage failure:
a) o'ring is dislodged, you shut the valve, go for your buddy's long hose, he fixes the problem, open the valve and you continue the dive as nothing had happened.
b) 1st stage is frozen, you shut the valve, go for your buddy's long hose, let 1st stage to recover, open valve and continue the dive
2. Free flow: you open and close valve and you're able to breath