Are you talking about SCUBA mask? As I understand it, with SCUBA the same tank will last longer than 45 minutes.
Any method that uses a face mask with a closed system will suffice, which includes scuba, scba and any other methods which don't allow air to enter into the closed system. Scuba, scba last longer since you don't need the over pressure to push air out and only use the inert gas to inhale. So it will last longer.
RU talking about a scuba mask. I am leaning towards this method as well. Any thoughts on if there are chances this method could fail? I think its the most foolproof of the inert gas methods but would like to know ur thoughts
The biggest failure points of the inert methods are knocking down equipment and compromising either the mask/hood/bag when becoming unconscious. With a mask setup the risk is lower since it's physically strapped to your face unlike a bag or hood, but it's still possible to lose it.
Securing the cylinder to something sturdy raisers the odds significantly since it often houses the regulator/flowmeter which is sensitive to hits and bumps, especially on hood/bag setups scuba and scba regulators are more durable.
To minimize the risk of falling down and compromising the inert atmosphere choose a suitable chair which prevents you from collapsing. Either with straps or pillows whatever that keeps you from falling down, a wingback chair with pillows or a recliner with straps for example.
These two important steps prevents you accidentally failure after you loose unconsciousness and possibly waking up alive or worse with brain damage.
But as long as your inert gas source is pure (98% at least) and nothing happens after you loose unconsciousness there is a very high probability that you will ctb using any inert gas method as long your equipment is working correctly. Any inert gas method mentioned here cannot support life when working correctly and the main target is thus keeping it that way.