No, you do not.
The flow of oxygen can be stopped anytime be stopped at any time by twisting the Regulator counter-clockwise and removing it from the Oxygen Canister. You can then use the remainder of the oxygen at a later date.
The flow of oxygen can be stopped anytime be stopped at any time by twisting the Regulator counter-clockwise and removing it from the Oxygen Canister. You can then use the remainder of the oxygen at a later date.