Nitrogen is better than nothing, but I'd like to go back to public hangings. Seriously.
I've read about hanging. Nitrogen is more foolproof, especially when the condemned is more than a standard deviation away from average height/weight. Hanging gets complicated - you have to calculate the height of the drop relatively carefully to successfully break the neck while not pulling the head off. Even the stretch of the rope needs to be accounted for, which is why most professional hangings were done with new rope, because new rope had known stretch, while used rope was more variable.
I know that people here might not care, but even the English of the 18th century cared about preventing that, and they were rather more bloodthirsty than modern day.
I want executions to be as fool-proof as possible. Put convict in specified room, flip this lever from "air" to "nitrogen", wait 30 minutes, flip back to "air", done. Better yet, put the lever on a timer so it automatically goes back to "air".
Hmmm...
Starting state: bar gate closed & locked, airtight door locked open, safety system locked for execution lever.
Switch air handling system on - constant fan, using filtered outside air. Nobody should be in the chamber without this being on. This also activates the scent unit.
Test O2 sensors(not alarms) inside room.
Test O2 alarms outside of room.
Verify that N2 tanks are full.
Inspect seals on execution chamber.
Inspect and fill heated "scent" unit that ensures that the prisoner can't smell the switch. I suggest "clean linen" or "lavender". Prisoner choice is an option.
Transfer prisoner to execution chamber. Lock door.
Await final approval for execution.
Verify, by video, that the condemned, and only the condemned, is in the execution chamber, and that the chamber is properly secured.
remove the safety ping and lock(s)(Warden is only holder of key, there may be additional keys required) from the execution lever. Note: There should be a mechanical safety that prevents moving the lever if the chamber door isn't secured.
Verify, by video, that the condemned, and only the condemned, is in the execution chamber, and that the chamber is properly secured.
Throw the execution lever. It is on a 30 minute timer(or whatever is determined to be optimal). This changes the air supply from outside air(filtered) to N2.
Verify that the O2 sensors show an appropriate decrease in O2 levels in the room.
Verify that O2 levels are remaining good outside the chamber.
Wait until timer is finished.
Return the lever to "Air", insert safety pin and lock in place.
Wait until the O2 sensor in chamber reaches normal(breathable) levels. - Note: Electrical lock should lock chamber until this is true.
Open chamber
Lock chamber - the airtight door should be secured open with the Warden's key.
Verify Death
Remove body.
Clean and refresh chamber.
Bar gate can be closed & locked. The barred entrance can be locked closed, but the airtight door shall remain secured open. Note: The room probably counts as a 'confined space' requiring special training to work in. People get themselves killed each year in them, even when trained, so we should be careful here.
Turn off air handling system - which should be on whenever there's somebody possibly in the room.