Second Air Tank for Moisture Control?

[bad_idea]

I am in process of setting up a Quincy 325 compressor in my 30x40x12 garage. I am plumbing the pump into a 80 gallon tank. I know this is plenty of air setup for my uses. BUT... I live in a swamp, well not in the swamp but adjacent to it. VERY humid area.

I am thinking plumb the pump into the 80 gallon tank, then plumb a 20 gallon tank (have an extra one) above the 80 gallon in the rafters. Then plumb my distribution piping out of the 20 gallon tank. The inlet to the 20 gallon will be on the bottom of the tank, and the outlet will be on the top. My thought is the air will expand again going into the 20 gallon tank and shed the remaining moisture before going into the distribution piping. The water will run back down the inlet piping back into the 80 gallon tank to be drained out the bottom.

Thoughts?

 

[cvairwerks]

Unless you are going to valve off the second tank, it will pressurize at the same rate as the first tank. Only time there will be any real difference is when you are flowing more air than the intermediate piping can supply. Just add a good coalescing filter before your regulator and you should be fine, assuming you place the regulator back at shop level, after the second tank. If you still have moisture problems at that point, nothing wrong with adding an appropriate sized desiccant filter after the regulator.

 

[Citation]

I am in process of setting up a Quincy 325 compressor in my 30x40x12 garage. I am plumbing the pump into a 80 gallon tank. I know this is plenty of air setup for my uses. BUT... I live in a swamp, well not in the swamp but adjacent to it. VERY humid area.

I am thinking plumb the pump into the 80 gallon tank, then plumb a 20 gallon tank (have an extra one) above the 80 gallon in the rafters. Then plumb my distribution piping out of the 20 gallon tank. The inlet to the 20 gallon will be on the bottom of the tank, and the outlet will be on the top. My thought is the air will expand again going into the 20 gallon tank and shed the remaining moisture before going into the distribution piping. The water will run back down the inlet piping back into the 80 gallon tank to be drained out the bottom.

Thoughts?

Your best best, absent some sort of dedicated dehumidifier, would be an after cooler with a water drain before the air goes into the main tank. Lots of threads on it here.
Here is one thread with some good pictures. Not saying this thread is the ideal setup, only that it shows the concept

My Compressor Aftercooler Install

I borrowed a lot of ideas from this forum. Hope this helps someone else. I wanted to install an aftercooler on the compressor because I'm going to do some sand blasting and I eventually want to paint the Jeep myself. For those that don't know, the idea is that the aftercooler lowers the...

www.garagejournal.com

Critically, the idea here is to cool the hot, compressed air so a lot of the water condenses out before it goes in the tank. Hence you need a water separating filter before the tank. The fabricated hardware in that thread is nice and probably overkill but it does look nice.

 

[American Locomotive]

You need to cool the air. Under continuous use, the secondary tank will eventually heat-saturate (especially since its small).

So ideally you need an aftercooler before the tank, after the pump. This will cause the water to drop out of the air stream, get pushed into the tank and settle on the bottom. A simple coalescing filter will grab most of the remaining water, and you can add a desiccant filter after that if you really want dry air.

 

[Jswain]

Other thing to think about is to make sure the 20g is rated for the same or higher pressure then the 80g tank.

If you were going to plumb in another 80g tank I would say worth it but I wouldn't waste time with a 20g, with the exception being if you had a long run to get to your blast cabinet or whatever at the other end of the shop you could plumb it in there.

 

[Ohmthis]

So I have differing opinions on what has been said. Obviously, hot air can hold moisture much easier. An inter cooler cools the air to the point that the vapor condenses and falls out of the air. When the compressed air is pressurized in a smaller line and then hits a bigger line (the tank is a MUCH bigger line) there is a pressure drop which quickly cools down the air and the vapor again falls out of the air. That’s why the tank collects water in the bottom. Having another tank will (in my opinion) have a pressure drop and condense water vapor out of the air. To me (and my plan on a smaller compressor) having the tank farther away, with the feed line draining back to either the tank or a water trap, will remove water. From there a line with another water trap and valve to remove water, then regulator, water/oil separator, and desiccant. I guess I will see how it works.

 

[Renegade1LI]

Why not use an air dryer with filters.

Compressed Air Dryer

Amazing deals on this Compressed Air Dryer at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[Jswain]

Why not use an air dryer with filters.

Compressed Air Dryer

Amazing deals on this Compressed Air Dryer at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I would guess the price would be one deterrent

 

[mrbill55]

I would guess the price would be one deterrent

In that case the OP could really use a simple 3 stage, industrial grade, in line coalescing filter and desiccant air dryer combination. Figure somewhere between $185-$300 depending on the quality.


Bill S.

 

[bad_idea]

Cost is wholly the reason! I have the extra tank. $600 for a dryer is a bit much for my uses. I much rather enjoy the thinking and problem solving to make it happen cheap or free with parts I have on hand.

Good call on the pressure rating of the smaller tank. I may still plumb it in at the far end of the garage to act as an accumulator for large draw items. If I do, I will use a regulator to drop the pressure going into the tank and retain the relief valve in that tank.

For my moisture concerns though, I will look into getting a coalescing filter. Recommendations on a good one?

 

[930dreamer]

I've picked up discontinued/new/ surplus items on ebay.

 

[Firstram]

Why not use an air dryer with filters.

Compressed Air Dryer

Amazing deals on this Compressed Air Dryer at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

$600!!

Working pressure of only 100 PSI. This dryer must be installed after the tank and regulator so, it does nothing to keep the water out of the heat soaked tank. Keep in mind, the higher the pressure, the lower the dew point.

Needs to continuously run!

Refrigerated dryers have a limit to the inlet temperatures. Unless the air is already cool(ish), this 1/4hp unit doesn't have the power to cool the air down enough to truly dry a large volume.

A large, fan cooled after cooler is incredibly efficient and affordable (relatively speaking). I have a 220v fan tied into the mag starter so, it just does it's thing whenever the compressor is running. I haven't gotten more than a few ounces of water out of the tank drain in years!

 

[Leaflessshadetree]

This has me thinking. What if the 20 gallon tank was before the 80 gallon and and up so the in and out were both above the bottom?

 

[mrbill55]

Cost is wholly the reason! I have the extra tank. $600 for a dryer is a bit much for my uses. I much rather enjoy the thinking and problem solving to make it happen cheap or free with parts I have on hand.

Good call on the pressure rating of the smaller tank. I may still plumb it in at the far end of the garage to act as an accumulator for large draw items. If I do, I will use a regulator to drop the pressure going into the tank and retain the relief valve in that tank.

For my moisture concerns though, I will look into getting a coalescing filter. Recommendations on a good one?

Keep it simple and easy to work with:
I recommend a DeVilbiss 130525 QC3 air filter and dryer


Bill S.

 

[Nortonscustom]

You're on the right track. Similar to my setup. My compressor sits on a 120gal at ground level and is plumbed into an 80gal tank. The 80gal is about 8' high. The main trunk line comes off the 80gal tank. Both tanks have auto drains. It's also really important how you plumb your branch lines off the trunk. Look at how the paint@sandblaster companies recommend running air lines. Each branch is plumbed to act as a water separator both at the top and bottom. Then have a simple filter/separator at the point of use. I also added an auto drain to the end of my trunk line.

If you plumb you're whole system to work as a water separator you'll be good to go without spending a zillion dollars.

 

[seber]

Norgren is a good compromise between cost and quality. Stay away from companies that do not make air systems as they simply put their name on another's product and bump the price. (Devilbiss, Binks, etc.)