Quote:
| Originally Posted by dave archer
Sorry, I'm new to diving twins, but nothing said so far explains to me why guaranteeing half my gas is not worth two seconds before starting to diagnose...
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Because most loss of gas problems are 1st stage/reg related, the chance of it being a problem that can't be fixed by closing left or right post are low.... therefore closing the manifold in my opinion only wastes time.
Having the manifold only partially open could create more problems. When you are stressed what if you turn it the wrong way? How do you know 100% which way is the correct way to turn. I've done shit loads of dives and I hit my valves sweet every time in practice, I open and close cylinders every day when filling them and it's almost ingrained. But i've seen really experienced divers turn them the wrong way when they were being videod just out of nerves. So i don't know for sure that i'll turn them the right way when it's real. So manifold all the way open takes a bit more than 2 seconds to close. This also helps prevent it shutting accidentally.
Also if it is an unfixable problem and the manifold needs to be closed, you actually haven't made yourself any worse off as you still have the same amount of gas as if you had shut it first, just spread a tiny bit more between 2 cylinders. If you breath the broken side down you will have alot more than if you had isolated first and then breath good side only. However if you plan to isolate first and breath broken side, you still have the same amount of gas as if you didn't isolate first. If you've ever seen how much air pisses out of burst LP hose you'd understand why you'd want to shut that post off first.
So in my mind it makes sense to try to fix the problem first, as closing the isolator gives me no benefit and in fact in alot of situations will give me less gas too.
I haven't mentioned the GUE team reserve as not all non DIR divers would have that backup.
Best,
Brian
EDIT by unfixable i mean that closing the valve doesn't resolve the gas loss. If ever a valve is closed and that doesn't stop the bubbling my instant reaction is to isolate