| Re: Bail out tank valves
I turn mine on to put pressure in the hose, keeping water from working its way up to the first stage during the dive. I turn it off after that. Underwater, I turn it on and off again periodically, just in case water movement or other events during the dive have caused the gas in the hose to leak out into the environment.
I prefer this method over leaving the valve on all the time. Especially when diving in a strong current or scootering, you might not notice gas leaking during the dive. If you were to need your bailout bottle, it could be a real problem if it had a lot of gas depleted from leaving the valve on.
Though I have never personally been there when someone leaked all of their breathing gas by leaving the valve open, a former instructor of mine was on a dive when another person did so (on open circuit, having to do a lot of deco on back gas). It can and does happen. This is why I would not leave the tank on other than to pressurize occasionally.
Leaving pressure in the hose should provide enough gas for you to start to get a breath when pressurizing the hose if you should ever need to bail out. It only takes less than a second to open the valve enough to get gas flowing in sufficiently to allow an adequate breath. |