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Re: air dryers 101

Subject: Re: air dryers 101
Date: Mon, 16 Oct 2000 21:46:42 -0800 wrote:
> I get very little water from the drains on the individual drops but a good
> bit from the compressor tank when drained every week or so.  Can I assume
> that a dryer would remove even more water from the air ??? 


OK John, I'll take a crack at this.

Basic principles: air can hold a certain amount of water for a given 
temperature before 
it reaches saturation (100% humidity) at which point it can hold no more water. 
air is compressed it is warmed (and can hold more water).  A problem can occur 
when you 
use large volumes of air. The compressor runs at a higher duty cycle, the air 
in the 
tank warms up (and holds more water), this warm, moist air runs out the line 
and starts 
to cool off. As it cools off and the air exceeds 100% humidity water condenses 
out.  In 
the galvanized lines that you have the water will condense on the pipe walls. 
If you are 
spraying paint, the air is further cooled by expansion and water droplets can 
form in 
the paint spray itself.  Have you used a die grinder continuously for a few 
minutes? You 
will feel it get cold and will probably notice water vapor condensing on the 

Now if you are not using air hungry tools you may never see this.  Your 
compressor only 
cycles occassionaly, the air which is heated by the compressor cools in the 
tank and the 
water condenses in the tank. As you use air, it is already relatively cool and 
so does 
not condense as much in the lines or in the tools.  

I think that the idea behind using coils of metal is to cool the air.  The 
water that 
condenses out can then be removed by a water separator.  A water seperator can 
water droplets but cannot remove water vapor. By following the TIP guidelines 
you will 
already get a fair amount of cooling as the air travels through the pipes. 

Does this make sense?


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