MIni Braze 2 Gauge Oxygen Regulator Replacement Seal - Viton "O" Rings.

Removing and refitting the MiniBraze regulator from the disposable canister does "injure" the "O" ring each time a new canister is fitted.
Before fitting your MiniBraze regulator to a new canister you must visually inspect the seal iwithn the regulator conneciton to ensure that it appears to be good condition.  If not replace the seal before fitting to a new oxygen canister.  
Noz-Alls supply oxygen compatible leak detection spray which should be used on your gas set at the start of every work period plus of course for leak testing every time you fit your regulator to the new oxygen canister.  The leak detection spray will help to ensure you have tighened the regulator sufficiently to prevent a leak - even a small leak is capable of emptying a canister in a short space of time.

From our experience we have found that oxygen canisters having been fitted to a regulator and the seal broken (by fitting the regulator) the connection and "stopper" valve in the canister connection thread will generally leak - best practice is to fit the regulator and leave the regulator in position.  We have conducted long tern pressure / leak tests with our regulators where the pressure in the canister did not drop over a period of four months.

Therefore should the regulator seal appear to be damaged do not fit the regulator to a canister because either the regulator leak or the canister valve leak will waste the gas.

Replace the seal before it is necessary - or ensure they are ready to be fitted in your toolbox, should they be required.