We have two 150 psi craftsman compressors - dual piston oiled devibliss. Nothing really all that good but it was all I could afford when we bought the first one in 1995. I added a second 30 gallon one same basic model that is fairly new and the owner needed a larger one. After consulting here, we decided to add a tee and female coupling on the tank side of the regulator and run a quick disconnect hose between the two. It works great although I want to drop the pressure to 125 on both compressors as although both are rated to 150 the one from 1995 has been cutting off at 125 for years. As long as the tanks are within their working life and they are not rusty, they should be safe. Tanks can explode especially when old, rusty or over pressurized. I would be leery to use a tank that had been sitting for years unless it was tested. The issue is the same for scuba tanks but because they hold roughly 3,000 PSI, it is mandated they be tested every 5 years. I would not have a clue where to even begin to take a compressor tank to be tested or tumbled, and frankly I can't imagine any (compressor) tank Sears, Lowes, HD or HF etc has sold in the last 30 years has ever been re-hydro'd.