I normally tumble dry, then rinse with 90% alcohol. The alcohol flash dries pretty fast, unlike a simple water rinse. Then invert the cylinder on the warm air dryer. It'll dry within 4 -5 minutes. The drawback of using alcohol is it obviously costs a few bucks more than water, and it requires venting, else the next air fill will taste like alcohol. Vent it by leaving it on the dryer for 10 minutes to blow out all the alcohol fumes.
I use the 90% alcohol that you find in CVS or medical supply stores. I'm told the 70% you find at WalMart, etc. leaves a carcinogen when it dries that the 90% doesn't.
Of course, you can just rinse with water, but you need a warm-air dryer else you'll get flash rust.
I made my dryer out of an old condemned scuba cylinder, a hot air gun, and some copper fittings. The only cost was the hot air gun (that I use in the shop for other things anyway) and a few bucks for the copper fittings.View attachment 618974
Never had a case of seeing rust in steel tanks I do that way on the next years visual. Use lead-free solder.
Interesting setup. Are there holes drilled into the copper standpipe?