Think about it this way … when the automatic shutdown occurs between 4200 and 4500 psi, it holds the pressure in the lines, the compressor and the tank. You close off the valve on your bottle or tank, then you crack open the bleed valve. When you do that, all 4500 psi is being pushed out the bleed valve until all pressure is released. Many a time I have been sprayed when cracking open the bleed valve. I leave the fan and water pump running until cool down is finished but while doing that I'll turn the compressor back on with a dead man in the line, put my finger over the bleed valve and get a little more out of the system. If it sits for more than a few days between fill ups, I'll turn it on and let it run about 5 or 10 minutes with the bleed valve open just trying to keep as much water out of the system as possible. I don't think you'll ever get it all out but in this case, less is more … or better.