Manifold open or closed?

[Jason B]

Diving with it closed is a waste of $200 bucks also. Why have a manifold if you don't use it...as Soggy said, your just introducing more failure points.

Jason

 

[DEEPLOU]

Fair enough, I've just never seen anyone close their iso on purpose.I will say that I used to close my isolation on my tanks when I travel with them, but I forgot to open it when I got it filled and they only filled one side. That sucked when I got to the dive site , opened the manifold, and watched my gas drop as the other side filled.

my experience was the other way around, (and yes I screwed up in not doing pre dive check of it) .
The ace who filled my tanks closed the isolator after he filled them. When I was at the end of my dive on the hang, I looked and "Wow" the spg still read 3000! At first I thought the needle was stuck, but then I reached back and opened the isolator (it only took a second) and as soon as it opened I heard a "woosh" and the gage dropped to abt 1600.

 

[Soggy]

my experience was the other way around, (and yes I screwed up in not doing pre dive check of it) .
The ace who filled my tanks closed the isolator after he filled them. When I was at the end of my dive on the hang, I looked and "Wow" the spg still read 3000! At first I thought the needle was stuck, but then I reached back and opened the isolator (it only took a second) and as soon as it opened I heard a "woosh" and the gage dropped to abt 1600.

Ouch...that could've led to a *really* bad situation as you now have a completely unknown FO2....If I discovered my isolator was closed during the dive, I would *leave* it that way and abort abort abort. At least I know that what I analyzed is what I am probably breathing. I might even go 'OOA' and share gas with my buddy who at least now has a known breathing supply.

 

[Soggy]

Fair enough, I've just never seen anyone close their iso on purpose.

That's because it doesn't make any sense to dive with the isolator closed....It's combining all the disadvantages of diving with an isolator (added failure points) plus all the disadvantages of diving independents (gas management)!

You've removed *all* the advantages of an isolation manifold in this situation.

 

[wedivebc]

That's because it doesn't make any sense to dive with the isolator closed....It's combining all the disadvantages of diving with an isolator (added failure points) plus all the disadvantages of diving independents (gas management)!

That is where you are wrong. It does have the same failure points as open manifold with the added benefit that I can determine the urgency of of a gas shutdown, not let the situation dictate it. I can also recover un-lost gas using the manifold if and when the situation warrants it. Like I said in my previous post there are times when it is more risky to attempt a valve shutdown than to switch regs.

 

[Soggy]

I can determine the urgency of of a gas shutdown, not let the situation dictate it.

Huh!?

I can also recover un-lost gas using the manifold if and when the situation warrants it. Like I said in my previous post there are times when it is more risky to attempt a valve shutdown than to switch regs.

I repeat....Huh?!

 

[Divesherpa]

I'll second the HUH?
I've heard logical arguments for diving independents (even dove indies for about 200 cave dives), but I've never heard a logical explanation for diving a closed manifold. If you can't shut down a manifold very quickly, there is a very serious problem.

The logic behind diving a closed manifold is not IMHO a defensible argument. I can see no situation where a closed manifold (without a failure) is a plus. What do you do in an OOA situation?

 

[riverdiver]

OPEN that is why you go through the drill open and closing manifold vavle. What do you do when you drop off your tanks to get filled and you have it shut off and they fill only one tank. Then you do a boat dive you end up with 1700 psi insted of 3400!
Ed

 

[Soggy]

OPEN that is why you go through the drill open and closing manifold vavle. What do you do when you drop off your tanks to get filled and you have it shut off and they fill only one tank. Then you do a boat dive you end up with 1700 psi insted of 3400!
Ed

Yeah...1700 psi of an unknown O2 % at that, unless we are talking about strictly air diving here

 

[MikeFerrara]

my experience was the other way around, (and yes I screwed up in not doing pre dive check of it) .
The ace who filled my tanks closed the isolator after he filled them. When I was at the end of my dive on the hang, I looked and "Wow" the spg still read 3000! At first I thought the needle was stuck, but then I reached back and opened the isolator (it only took a second) and as soon as it opened I heard a "woosh" and the gage dropped to abt 1600.

LOL

You went the whole dive without noticing that the needle wasn't moving? I saw a guy do that once in a normoxic trimix class and boy did he get skinned.