On Sat, 4 Jan 2020 14:50:31 -0800 (PST),
wrote:

I have done this many times.first wash out tank with liwuid gunk degreaser.flush it good with water.but tank on bench.stick airhose in tank low preasure.leave tank sit 5 minutes.leave airhose in while welding.no stangent fumes no explosion.a old mortorcycle mechanic taught me that 50 years ago
filling it with co2 from a fire extinguisher works pretty good.