I heard some folks were looking for the driest air compressor. Sorry all…no such thing.
Every compressor using free air will generate water. It’s the nature of the beast.
Free air (the stuff we breathe) has water in it, in a vapor form. Some days it’s got lots of water, other days less, but it almost always has water. Some days it seems like it’s 100% water…remember hot, humid summer?
Take about eight cubic feet of that free air at 14.7 PSI (one atmosphere) and compress it to one cubic foot in size, to generate normal compressed air pressure (about 120 PSI) . You now have eight times the water vapor in one single cubic foot.
That concentration of water vapor in the compressed air exceeds the capacity of that air to hold water and the extra water vapor that the air can no longer hold condenses into free water. It pools in the bottom of your compressor reservoir (receiver) and it blows out along your air lines to your application.
The amount of water you get depends on how high you pressurize the free air, how much air you compress, and the relative humidity of the free air that you are compressing. You will always get free water when you compress air.