I am going to see if our welding supplier at work can hook me up, I don't think anyone would notice a 15# tank thrown in with tanks for a dozen huge MIGs. I am excited, according to the site that sells PowerTank CO2 set ups, a 15# tank of CO2 is comparable to a 960 gallon compressed air tank, which is probably a little high but close enough - I am too lazy to check the math. The site also says a 15# tank contains 126 cubic feet of gas, so, I should be able to run an impact gun for about 40 minutes on a tank.