>I would guess anything that will absorb moisture would work. Some diapers
>have exterior linings to prevent moisture from passing through the outer
>layer. That may hinder moisture absorption. The person I know that used
this
>homemade dryer used the cheapest napkins he could find. Get the girl friend
>or neighbor lady to make the purchase for you. Waded paper towel may also
>work. At any rate put the dryer at the end of a hose and not directly at the
>compressor. This will give the moisture a chance to condense in the hose.
Getting the moisture out of compressed air is a pretty rudimentary
science. There are a number of things you can do to "wet" air to
make it give up disolved water molecules. Contact with LOTS of
surface area (like the fiber filters cited) will take out SOME
moisture . . . but once it becomes saturated, it's not going to
take any more out. Same thing with hygroscopic materials like
silica gels, kitty-litter, etc. The hygroscopic traps need to
be periodically regenrated by baking the absorbtion medium
in an oven at 250F + degrees.
Having wrestled with the wet air problems in two facilities
I'll have to suggest that COOLING the compressed air is the
BEST way to get it dry. Our large volume air distribution
system at Electro-Mech took the warm compressed air right out
of the compressor through a fan cooled heat exchanger. The
inner tubes were sloped so that water condensing on inside walls
of the exchanger ran downhill into a trap at the low point.
There was an automatic drain at the bottom of the main storage
tank. This exchanger trap and tank drain removed the vast majority
of air ingested. The next step was to slope all horizontal runs
of distribution piping downward at about 2" per 10' so that
water condensing out on piping was swept toward far end where
there were more traps with drains. Branches off the main distribution
were T-connections pointing UP were a 6" upward stub made a
u-turn with two elbows before dropping to the factory floor.
This prevented water lying on the bottom of the distribution
pipe from being swept into the final distribution drop line.
When the air needs to VERY dry, you cool it as much below room
temperature as possible. I had an ice bath in one lab that
surrounded about 50" of 3/4" copper tubing. Again, down-sloped
tubing feeds a lowpoint trap and drain. The final step was
a hygroscopic filter that would push the moisture content down
to a few milligrams per liter at 100 psi.
For higher volume flows like for spray painting, log runs
of distribution piping at room temperature (air conditioning
in your shop does wonders for drying air in the lines) is pretty
inexpensive and easy to build. You need to use copper line for
this . . . plastic is okay pressure wise but doesn't cool the
contents fast enough to precipitate out the water. You can build
a dryer out of 3/4" copper and zig-zag a run on the wall for
as much length as you care to buy and assemble . . . I'd
suggest 40' as a minimum. Space off the wall and blow ambient
air over it with a fan. Put a low point trap and a good riser
from the trap to your supply line and you'll be surprised how
much water you can drain from the trap every hour.
One builder I met at a fly-in told me about a dryer he made
with an ordinary refrigerator. He build a loosely coiled
copper "still" trap from 100' of soft copper. He installed
it in the cold-box volume of the reefer and put some circulating
fans inside. With the fans running and the box set for max cold,
he was able spray very water sensitive paints in his Houston TX
shop with outside humidities running in the 60s . . .
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
http://www.aeroelectric.com
|