For a given amount of compressed air the moisture content is fixed and the same regardless of the compressor. It’s just a question of where it condenses out. In the tank or down the lines. A compressor can’t create moisture, the moisture is in the intake air regardless of pump speed etc.
At least this is my conclusion.
Don
Don, your post was absolutely correct. It helps if you look at moisture as grains of moisture rather than relative humidity. Relative humidity for a given volume changes based on temp, but grains of moisture does not. Relative humidity is just that, the amount of moisture in the air compared to what it is capable of holding. Warm air can hold more moisture than cold air, but this does not mean that the actual amount of moisture changes as the temp goes up or down, only the relative humidity. As you compress air, the volume of air increases, and the grains of moisture goes up in direct relation to the volume of air. If you had 10 grains of moisture in outside air and you compressed that same air to 150 lbs, you would have 100 grains of moisture.
Since there is a known amount of moisture that air at any temperature will hold, the moisture that is in excess of what that air will hold, condenses out in the tank, period. Condensation only occurs until the air drops to 99.9% relative humidity, and never decreases any further, unless the temp of the tank drops lower. The fact that air in our compressed air systems is always at a saturated condition (100%), leads to the problems we have with painting. When this saturated air reaches the nozzle of your gun, the temperature drops dramatically, and moisture will condense out this cold stream of air. Everything that can be done to remove this moisture prior to it arriving at the nozzle of your paint gun, will be of great benefit to avoiding moisture problems in the paint. Cooling the tank off by placing it outside like Shine does, helps. The truth is that unless you drop the temperature of the air below about 34 degrees, there is a good chance that you could be condensing some moisture out at the nozzle of your paint gun.
How many times have you been running a grinder for an extended period of time, only to have the grinder get so cold that you had to put gloves on?
That is how cold the air can get when the pressure of compressed air drops substantially. In my opinion I can not imagine operating a spray booth with out at least a refrigerated dryer at the minimum, and with a desiccant dryer if you really want to be safe.