Confused ney baffeled by replys to this question:
Somthing goes bang or fizzz and you are surrounded by bubbles:
1: Isolate manifold NOW
At least you have half the gas left and if you have a slob knob or are double jointed that took about 2 seconds
2: Identifie source of gas loss (or if serious swap to back up reg if required or bail out to stage and ascend)
This could be any thing: High Pressure hose on deco bottle, reg free flow, O ring failure etc etc.
Identifie and shut down offending item if possable before total gas loss.
3: If apropriate re open manifold to redistribute un used gas to breathing reg and start ascent
Long and short of it is if there is a catastrophic failure in any air containier first move is isolate manifold. If the reg in your gob stops working thats a good indication that thats the problem so swap to back up reg. If that dosent work go for stage or look for buddy dammed quick.
You cant practice for the panic you will feel but at least if you shut down the mainfold in a few seconds you will more than likley have the remainder of one tank to get you to the surface so practice that.
Oh yes whilst you are doing all of the above start finning for the surface at a controled rate. Unless you have a total gass loss then the prefered DIR method is finn like bug#er
Mark Chase