CB,

Of you are on a gas handleing course then every time you reclaim the remaining gas, leak check with ofn, fix leak, retest, vac and gas.

Now in the real world, you are not going to reclaim a supermarket pack each time a ball valve leaks

Due care, attention and common sense is the nearest to an answer i can give you, there isnt a black and white answer it just depends on the system size and if you can find a leak or not.

I guess this doesnt answer youre question but all i can say is the official line is as the first paragraph and where you decide to go from there is up to you. Remember gas is classed as a hazardous waste, the powers that be dont seem that interested at the moment but i suspect sometime in the future they are going to start looking at the big boys to see what they do in these sorts of cases

Regards

Raymond