Bit of info about doubles for a technical noob :)

[Blackwood]

Ok. I think I get it.. So if I were to turn the Isolator off then each outlet would be for the actual individual tank its attached too. but then how do you actually turn the tanks on and off if the valve jsut turns the outlets on/off.. or am I just being stupid now?

Think of it less like you're turning the tank on or off and more like you're allowing gas to flow to the attached regulator.

The gas is in there. It's in the manifold even when both valves are shut. But I can't open the left post (regulator) and go suck the left cylinder down through the manifold via the right post if the right post is shut since no gas will flow to the right post.

Look at a manifold in cross section, that may answer your question better.

 

[iztok]

I've been taught two different sequences, and the only thing that's really important about the differences is remembering which sequence to use in front of which instructor

I figured!

But I thought that in DIR it has some deeper meaning (the sequence that is). Like reason why there is no right hip D ring.

 

[Chris Brown Tech]

I figured!

But I thought that in DIR it has some deeper meaning (the sequence that is). Like reason why there is no right hip D ring.

No, not really and its always being reassessed and modified if necessary. Ive seen it evolve over various DIRF classes we have had at the store.

When students are new to doubles, they have to get used to the valves opening and closing in opposing directions. Its important (for me anyway) when Im teaching to see students turning the valves in the correct direction and not twizzling back and forth to work it out. The valve drill builds this skill and also stretches out your muscles so that you can reach the valves more easily. The other purpose of the drill is to develop the ability to perform it whilst maintaining a constant depth and position whilst staying in trim. It develops the small backwards kick that helps with positioning.

 

[Griff..]

Alright I think I've got it..

So If I were to close the isolator, and have both valves open, each regulator would take the air from the individual tank its attached too..

Then If one regulator/tank is turned off.. that regulator will not function, however the other will still drain air from that tank...?

Then if both are off your ****ed..

right?

Regards.
James

 

[Blackwood]

Right,

Half right (isolator needs to be open),

Right.

 

[Griff..]

Thanks everyone

 

[Superlyte27]

Do you plan on taking the information gathered from this question as your sole instruction on technical diving?

Because there are people who post on this site that insist using a bungee necklace on their long hose is a "personal preference".

It is a personal preference, at least in my country.

 

[NC Wreck Diver]

James:

It sounds like you got it in theroy, which is good. I only dive doubles. All my sets have Isolator Valves and Manifolds. You can though, as was mentioned, dive independent regs on both bottles. I don't like this for me, but some do. If does give you some redundancy. Remember, if you are going to advance your diving with doubles, get in front of a good instructor. The illustration of the cut away of XS Scuba's manifold that was posted will really help you before you buy anything.

Mix the theroy with really thorough instruction. And, IMHO, I sling a 30 pony too. It's nice to take a lot of gas. Good luck and be careful.

Safe diving to you.

Right.. So I'm looking to broaden my diving ability/knowledge and start diving doubles and get into more the technical side of diving.

So trouble is.. I've dived with people on twinsets.. I know theres a Manifold, and two second stages.. but thats about all I know..

It would be greatly appreciated if someone could help explain to me.. how it works...?

does each tank have an individual first stage with the manifold connecting the two so either stage is breathing from both tanks.. then there is 3 valves.. what does each do?
turn the stage off?

I'm just getting myself abit confused and having people say different things..

would be great if someone could explain it to me..

Cheers
James

 

[Dr Wu]

Alright I think I've got it..

So If I were to close the isolator, and have both valves open, each regulator would take the air from the individual tank its attached too..

Yes.

Then If one regulator/tank is turned off.. that regulator will not function, however the other will still drain air from that tank...?

No. Once you isolate you can only breathe from whichever tank and regulator you have in your mouth at the time.

To isolate makes what was once "one big tank" two halfs of a whole.

 

[Dr Wu]

It is a personal preference, at least in my country.

I should hope so.

There is no reason to deny anyone the right to bungee their long hose.

It provides a feeling of accomplishment and safety to the diver with the added value of perplexity and amusement to others.