The argon/CO2 purge is to get the oxygen out of the tank, before I start sloshing around the chain. With everything grounded, static cannot build. Even in the extremely unlikely event the chain would spark, with the oxygen purged nothing would happen.

After I drain the tank, I'll leave it open to air and in the sun. It's 90*+ ambient right now, in a couple hours the tank will be perfectly dry. MEK is extremely volatile, it will cook off quick. A blast with compressed air and it'll be good to go.