Auto Nitrogen Gas Valve Timer

[SadCryingBunny]

Looking for Gas Auto Turn On Valve for Type 50 Nitrogen Tank Valve. I'm in Australia. I want to be asleep when the gas turns on. I will have a large 18L 232Bar or dual scuba tank full of oxygen flowing into the exit bag while I'm asleep. I will tune the oxygen bottle to finish at exactly 2 hours. At 2 hours, the nitrogen valve will switch on and fill the bag with nitrogen while I'm heavily in deep sleep. This is essentially the most peaceful death.