New air

Paul Downes

Member
Messages
959
Location
Westphalia, Michigan
My compressor blew up for the second time this past Fall. So I have been looking and checking Craigslist for a few months.

Last week I almost ordered a Quincy QT-54. Found one locally on Craigslist, nearly new, for $3-400 cheaper. It's sitting in the shop today. Need to run a new circuit and might just run all new air lines.

So here is something I am looking into. I want dry air. So I am thinking about engineering my own system. I simply don't want to spend an extra $200-1000 on a commercial air dryer.

I'm thinking about running the air from the compressor head into several vertical pipes 12 ft. high with drains in the bottom. Next I will run the air from the tank into particulate filters and then into a home made desiccant filter. I just can't see the value of buying desiccant filters at $50-100 each. Especially when I can buy 1.5 lb cans of desiccant from Walmart. Silica gel can be dried out in an oven or in a dehydrator for next to nothing.
 
:lurk:

Sounds like a fun project and congrats on the new toy!

It would be interesting to know how much you got with just the cooling tower without the desiccant. I don't know how you'd measure that though..
 
I may skip the vertical pipes and weld up a Stainless 3" diameter pipe with stainless scrub pads stuffed inside. The added surface area of the pads will cause more water vapor to condense out and drain to the bottom. At least I can get by with a smaller system. I'm hoping to get 90% of the water out this way before it hits the desiccant. I already have the pipe for my business so it is no real expense. The question is how much length does it take to cool the compressed air.?? I might just make one and see how much cooling I get for that given length. Cooling = condensation. I got these ideas from Youtube video's and other articles.

I haven't done much finish spraying yet. I am usually just a spray can and brush kind of guy. However, I now have to build a new kitchen and also have a grand piano in the shop that needs a new finish. Spraying is going to happen this Summer. I am looking at the Earlex HVLP but also have spray guns so I need dry air for the spray guns. I have had air tools freeze up in use because of all the water in the system. Not good for the tools and too cold to hang onto.
 
Watching this one. Especially when you get to the home made drier part with the desiccant. And how DID you figure the pipe lengths?
 
I might go with something less likely to corrode that stainless, marbles might work (I've used them in other vapor temperature management columns with some success).
 
Why would stainless steel corrode? Perhaps I should build the pipe with a threaded end so it could be cleaned out?

Pipe lengths are not figured out yet. I can build the stainless steel/scrub pad section to whatever length I choose. I use 100's of the scrub pads in my business. I haven't seen them corrode yet. They usually just break down from physical use. After the air goes through the condenser tubes it is piped back to the compressor tank. I will see how much water goes to the bottom of the tank.

I am going to look around for a suitable cartridge canister to fill with desiccant media. I just need one that is rated to 300 psi or better. (I like to overkill pressure requirements, I think the compressor kicks out at 175 psi.) If I have to make one I guess that is an option.
I have an automatic water purge valve. (don't know if it still works, I may have to get a new one) I will add this in the system after the tank. Putting some drops with drains between each element might be a good idea. At least I can see how much water collects at each point. I also have an automatic oiler which I will put near my metal work bench.
Before I just had air piped around the shop with the purge and oiler right at the compressor. BAD idea. Had water and oil at every quick disconnect. With the new system I am hoping to get most of the water condensed out before the desiccant filter.

I am also planning on picking up a plasma arc cutter. These require dry air. It is nice that this stuff is needed for my business. I can write off the expense.
 
Oops I saw steel wool and missed the stainless. Never mind! Those should be fine I'd think. Glass beads might nominally have a higher thermal mass but if have to do math to prove it and that's not happening today.
 
Congrats! That's a great compressor. :thumb:

For air drying, this is an old post but this setup served me well:

http://familywoodworking.org/forums/showthread.php?9521-New-Air-Line-System

I used to get quite a bit of water out of the drying rack, and the drain drop right before my desiccant filter never spit out more than a few drops of water.

When I moved my shop I kept all the pipe (including the drying rack), so I intend to set it up back up in a similar manner when I get my shop set up.
 
Also don't forget that "treating the air" before it goes into the compressor goes a long way also. The desiccant stuff that you change out because it changes color can be dried in a microwave and reused. Good luck.
 
Hey Vaughn, thanks for the reply. I have one question. Why have the condenser system after the air collector tank? My concern is to prevent much water collecting in the compressor tank. So if I run the air from the compressor head into the condenser system and then back to the tank at least there shouldn't be much water sitting in the tank that long. I suppose the pipe would have to take 200psi rather than 90 psi after a regulator. I don't have an automatic purge on the tank now. Nice buy on the desiccant filter!! I will keep my eye out for such a deal. I just don't see why they cost so much. you can buy silica gel at Walmart for $10/1.5 lbs. I'm trying to remember where I recently saw some 1/2" wall clear Lexan 6" diameter tube. That stuff can take some serious psi. I could then build a desiccant filter for a few bucks. I have a friend with a CNC mill so it would be simple to cut some circular channels in some plate and basically make a cylinder/ canister to hold the desiccant. I guess I'm just cheap. Stuff like this is a great way to learn new skills.
 
I have an automatic tank drain on my compressor. It activates for a second or so every hour when the compressor is on, as well as at start-up. Mine is made by Ingersoll-Rand (I-R), but other brands are also available.

Drain2 [800x600].jpg Drain3 [800x600].jpg
 
If you put the condenser between the pump and the tank would you need a pre-chiller to drop the dew point enough to get the moisture to drop out to a useful amount?

As I understand the setup the condenser basically acts as a refrigerator unit where the air expansion cools it causing the dew point to drop which then drops the moisture out (in theory a series of contraction/expansion points should increase this but I suspect it would have a deleterious effect on airflow).
 
The pipe runs and Stainless scrub pad tubes should act like a cooler.

I do have one issue with the stainless tubes. Stainless steel is something like 47% less efficient thermodynamically as compared to mild steel. I'm not sure if it can dissipate enough heat to make the cooling effect last very long.

I may try one tube and see what happens. I can always write the experiment off to something learned that I should have known. I can always go to a system similar to what Vaughn was using. The other option would be to use mild steel or aluminum tubes and weld fins inside and out to collect/dissipate heat.

I know that commercial condenser units are now sometimes coated outside with a thin plastic layer to prevent corrosion from ethylene gas. These tubes are just up-sized slightly to account for the heat conductivity loss from the plastic. I wonder if the compressor tanks are coated in the bottom/or inside to prevent rust?
 
...Why have the condenser system after the air collector tank?

I'd say it was partly because I was just following the same methods I'd read about other people using (using the tank as the first stage of condensation), and partly out of convenience...I didn't want to modify the hard air lines between the pump and tank on the compressor. When I was using it in the relatively dry Los Angeles foothills, I'd typically open the bottom drain on the tank daily when i was using it a lot, and maybe weekly when I wasn't. (I kept left the compressor on all the time.) My compressor has a 1/4" drain line with an elbow and a ball valve that's easy to reach. It never took more than a few seconds to blow out any collected water, and I just blew it into an old bath towel to collect the water.
 
Glad to see this idea is still serving people well...

My system is still functioning well, never a drop of moisture in the last drain and my loops are only 5'...

As for the question about surface area........Think cool surface area... That's the reason for more pipe, the ability to dissipate heat..

I suppose you could use a water jacket to cool the exterior of your 3" pipe but I've gotta wonder what you'd gain given that the wool in the center would heat up quickly...
 
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