Proof that a desiccant dryer on the input to a Shoebox stops water

[AlanMcD]

Yesterday I decided it was time to inspect my guppy tank for any signs of water making it through my Shoebox set up with a big Wilkerson desiccant filter in the air path (see picture).

I have had the Guppy for almost two years, and my log sheets indicate that the tank has had about 350 cubic feet of air through it, all coming from my Shoebox set up. 
My calculations of the potential liquid water content, determined through absolute humidity calculations, showed that ideally I would have no water in the tank, and if things did not work as expected, potentially I could see at most about 1.5 ccs of liquid water in the tank by this time.  So before I topped it off this time, I decided bleed it down and open it up for a visual inspection. 

Bottom line - the tank was bone dry and looked like it did when it was new.  I even put a bit of paper towel taped to the end of a dowel and dabbed it around inside just in case there was a light film of moisture in it, and the paper came out absolutely dry too.

So this shows that if you use a big enough dryer - I don't think those little ones that can turn color in one or two fills are adequate to fully scrub all the air - with an air charge that is fully cooled down to ambient temp before entering the dryer (as is my case, with the shop compressor in the garage and a long manifold heading to my workshop), you can get fully dried air using a dryer upstream of the Shoebox, rahter than having to do it after compression.  With this big dryer, after 145 hours of run time, the desiccant still has not begun to change color (it is rated for 11,000 cubic feet of drying and I am still under 1000 cubic foot of air through it).

Obviously a drier after compression is sure to work well, but then we have to fill the filter to tank pressure and then vent it when done, which just takes a good bit of extra time with a Shoebox.  With a good sized dryer on the input side, we don't have to do it that way.  Just thought I would share the proof that this works!

[Hoosier Daddy]

Good info Alan, Thank you.
I see you have quite a nice set-up there.
Notice you have a timer in line to it's own onboard 120v outlet. Good idea, How long do you run it?
 After the desiccant drier, is that another separator? You ever get any moisture there? Would it be better to have the bowl separator before the desiccant dryer to extend the desiccants life?
Then do I see a regulator with a gauge? What are you dropping the PSI down to?
I thought that would just increase the fill time.
Sorry for the questions just trying to get some ideas for when I get one myself.

[AlanMcD]

What you see going from left to right in the air path is first a 1/4 turn ball valve (if you don't close off the air path, the desiccant will just pull water vapor out of the ambient air and become saturated earlier than needed), the big 1.5 lb capacity Wilkerson drier (bought from Zoro tools for a good price), a 0.1 micron particulate filter (not a typo - it really is that fine) to catch any dust thrown off by the desiccant (which does happen), then the regulator with gauge going into the Shoebox Max.  I run full pressure through the filters (anywhere from 120 down to about 100 psi) and then limit it to about 100 psi going into the Shoebox Max.  If I had the Freedom 8/10 I would not have the regulator there, but probably would have the gauge.

I don't need a separator before the dryer as I have one built into the manifold system in my shop - no condensed water can get into that manifold system on the Shoebox.

I run the Shoebox with the cover off and a fan moving lots of air over it to keep it cool.  That timer in the picture is basically a backup unit that limits the max run time to whatever I set that at - it maxes out at 2 hours.  I noe actually use a digital timer that everything you see there plugs into that controls the time to the minute.

Since I now fill an 18 cuft Guppy tank, I usually only run the Shoebox for under an hour anyways - most runs are around 40 minutes or so.

I believe the fine particulate filter may be playing a roll in how long the o-rings are lasting - I am at 145 hours of run time and it shows no real signs of needing to have the cylinders rebuilt.  There may be a bit of drop off in fill rate lately, but not much - I may rebuild them soon just to see if it improves.

[Taso1000]

That's a very nice setup Alan!

Taso

[Hoosier Daddy]

Thanks for the step through of your system Alan.... Very Nice is right!

[FuzzyGrub]

Hi Alan,

Thx for the inspection report.  I need to do the same and check my guppy bottle.  I did add a mini gold filter in the last year.  I have inspected it after each fill, and not found any moisture yet. 

PS: I wonder where I got that timer idea from?