Why use doubles?

[RJP]

I specifically wanted to exclude the argument "to carry more gas".

I know, that's what makes it a faulty premise.

You asked for the DIR reason to go with doubles. The DIR reason to go with doubles is to carry redundant gear and redundant gas.

You can't ask for the DIR reason, and then specifically exclude "the DIR reason" from the response.

"I'd like to know what 2+2 equals, but I specifically want to exclude 'FOUR' from the answer."

:14:

 

[amascuba]

Recreationally, If your tank volume is within your minimum gas, then it doesn't matter.

 

[El Orans]

I know, that's what makes it a faulty premise.

Nope, I carry more than enough gas. So, for me, that would not be a reason to use doubles.

I wanted to hear the other reasons why doubles are better than a single with a T-valve.

"I'd like to know what 2+2 equals, but I specifically want to exclude 'FOUR' from the answer."

In this case, four is not the only answer.

 

[Tienuts]

FIRST: your question contains a faulty premise by specifying "a set of doubles containing the same volume as a single tank" unless you're talking about a set of AL40's doubled up.

Actually, it obviously depends on the cylinders and their fill pressure.

Here in FL, double AL-80's are common, which is actually 154 cubic feet of gas when filled to 3000. So are overfilled LP 120's. An LP 120 with a "Florida" fill will hold 181 cubic feet of gas.

Take a closer look at the pic. That's not a H.

Edit: ehm... yes it is.

It actually appears to be a Y-valve, not an H-valve. An H-valve would have one handwheel sticking up.

Like others have said, this setup lacks the redundancy of a isolator valve in the event of a burst disk failure, or extruded neck o-ring.

 

[RJP]

Nope, I carry more than enough gas.

Right, but it's not REDUNDANT gas if it's in the same tank, since a single mechanical problem can prevent you from accessing ANY OF IT. Isolated doubles provides complete redundancy.

In this case, four is not the only answer.

Perhaps, but don't lose sight of the fact that it is the CORRECT answer.

 

[El Orans]

It actually appears to be a Y-valve, not an H-valve. An H-valve would have one handwheel sticking up.

 

[deepstops]

Tony,

Yours and Jimmer's are the only correct answers here so far.
El took the Fundies class where this was all explained, this must be a troll

Looks like one of those strange Sanosub valves to me.

BTW, those hose protectors need to go, they cover up (potential) problems.

 

[El Orans]

El took the Fundies class where this was all explained, this must be a troll

Nope, this wasn't discussed in my Fundies class.

 

[orange_diver]

I recall another member's (Dr. Bill?) harrowing experience with a piece of debris clogging his diptube and immediately stopping all gas access on his single, leading to a CESA from 70' or so...

CESA wouldn't be necessary with doubles. ;-)

 

[deepstops]

Nope, this wasn't discussed in my Fundies class.

Then you were short-changed by your instructor IMO, it was certainly covered in mine back in 2002.