I don't bother to depressurize any of the ones we have around the farm, except for once in a great while (to open the bleed valves). We've got an impressive redundant air compressor system in one of my uncle's quansets. I'm *thinking* that they're 200 gallon each, but I'm not sure. One on the right side of the shop, one on the left... pipes for drops the entire length of the shop. If one of them goes down, there are also valves to have one compressor power all of the shop drops. 🙂
hehe It's funny when some unsuspecting kid walks up and pulls the pressure relief switch on one of the tanks... hahaha That happened one time, scared the crap out of him!