Don't forget about the new 22B freon that is coming onto the market.

Another quick way to evacuate a system is the hook your hose up to the High side and evacuate the freon till the pressure equalizes in the cold reclaim tank. Then continue the evacuation from the low side till the system is empty.

If you test your recovering freon for acid and it tests negative I generaly use a dryer in line with the charging hose and reuse the freon that test negative.

I will add this, if an individual came to me and said I have a reclaim tank that is full and wanted to sell it to me I would not buy it and use it. I only use what I know where it came from. Too much liability involved.

Then you also have tecks that do not pay attention to the equipment and the type of freon that was used. I am currently in the process of changing out a compressor on a system because a service teck charged an R22 system with 410 and didn't realize what he had done, he evacuated the system of the 410 but did not flush the syste out so now I have a compressor to change out because of a stupid mistake from a non caring teck that is known around here for doing bad work.