# Dry Shop Air - Step 1 (Compressor After-Cooler)



## MtnBiker (Aug 28, 2021)

We should be getting our CNC plasma table in September so we're getting the shop ready. Plasma cutters like clean, dry air and compressors like to make water. After about a zillion YouTube videos we had our shopping list.

For those unfamiliar I'll describe, maybe oversimplify, the water problem. Compressed air cannot hold as much water vapor, at a given temperature, as air at ambient pressure. At about 100 psi, air can hold only about 1/8th as much water in the form of vapor. While compression heats the air and offsets that effect to some extent, once the air in the tank cools down water will condense out and pool at the bottom. That's why you need to drain your compressor tank. Even then, you'll still have water in your air lines. Plasma cutters will eat consumables, paint will get fisheyes, tools can rust. Not great.

One strategy to solve the water issue is to use a compressor after-cooler. Lots of different ways to do it but the gist is to cool the hot air coming from the compressor pump before it goes into the tank.

I chose to go with a fan-cooled radiator for this purpose. It is compact, cheap and effective.

Looks like the most popular radiator for this task is the Derale 15300 available on Amazon. Comes with size 8 AN connectors which aren't too restrictive and this model has a max operating pressure of 250 psi so it should hold up well with compressed air (but YMMV as these are pretty cheap).

The compressor pump will be connected to the top AN fitting (gravity feed when the water condenses).



The next component is an in-line water separator.  The THB brand 1/2" Water Separator with Automatic Drain seems to be quite popular since it has a float type drain. Available on Amazon. Unlike some, this one will empty when full even though under pressure. Good choice for this application.

The bottom AN fitting of the radiator runs to the water trap. Since the air is now cool and still pressurized, water vapor will condense and will settle in the moisture trap keeping it out of the tank. Or at least that's the idea.





The next component is the 10" cooling fan. Most everyone is buying cheap radiator fans on Amazon or Ebay. Got this one because, well, how can you argue with a fan made by MOSTPLUS. There are seemingly 742 brands of the same basic fan. All cheap. This one was reviewed by a company that runs it 24/7 and it lasts for 6 months each time. For our application, that is longer than we'll be in this shop so it should work perfectly. Forced air through the Derale radiator pulls some serious BTUs out of the air line.




Finally, we needed to run power to the fan when the compressor was running. You can find these PC power supplies on Amazon for dirt cheap.




This Joylit 12V 10 amp runs on either 120/240. Attached under the compressor pump mounting plate via industrial adhesive tape. Very easy to wire into the contactor on the compressor. Runs the fan when the compressor runs. Easy peasy.

To put this all together we needed two things, 1) plumbing and 2) some structure.

Time to remove the original plumbing (which is super simple but man did we get a lot of water in the tank). You can see that we started replacing pipe fittings/compression fittings with AN fittings




I will give a shout out to Hose Power (a Bridgestone company). We have three locations in Phoenix - seems like a national chain. These guys make industrial hoses to order. Very affordable for what it is. I went with braided stainless/PTFE rated to 500 degrees. Spec'd with AN fittings, it is a really clean, easy install. Most folks are bending copper which works of course. Just more of a hassle trying to connect from AN to something you can use with Copper tubing. And in the back of my mind, sending more vibes to a cheap radiator through rigid copper pipe doesn't seem optimal.




Armed with hoses, we needed to fab up a mount for the radiator.

A lot of folks just hang the radiator on the mesh guard behind the compressor pully/fan. Not a lot of CFM seems to me - more of a gentle breeze. Big air gap. Really wanted something moving more air and generating more pressure through the cooling fins. We planned a wall mount and with some cowboy engineering we built this:






This is a piece of wall space that can't really be used for much else. Radiator fits great. We used rubber car door trim on the brackets and some foam pads underneath to insulate and protect the radiator a bit - some vibration still comes through that stiff hose.

This is the after-cooler with plumbing attached:




A lot of folks want to keep everything inside of the original compressor footprint. I get it. This is still very space efficient and the orientation keeps the install pretty clean I think.

Finally, mounted the fan to the radiator. Pretty happy with how this turned out. Notice the tight seal. We should be getting some good air flow/heat transport. Those t-slot mounting brackets allow you to slide the fan to be flush with the radiator fins. We did a pull (you can reverse polarity and push) since the radiator is facing cooler air conditioned air.




First test complete, which if you are sharp eyed you'll realize didn't involve using the MOSTPLUS (not wired yet). I just held up a Vornado in front of the radiator. I'm really impressed with the temperature differential. The input air fitting is blistering hot and the outlet line is essentially ambient temperature when it hits the tank.

I'll post Part 2 showing the air distribution system and the other components we're using to get dry air to our plasma cutter.

Here's a preview - this holds more desiccant than that last bag of beef jerky you bought.





Hope this helps answer some questions and serves as a little inspiration.

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8/28 update: tank sat overnight and still no mist coming out the drain valve. Pretty cool.

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8/30 update: if you really crack open the tank drain you get a little mist. After doing more homework - the air in a compressor tank is right at 100% humidity given the higher dew point of pressurized air. The after-cooler just dumps the condensate before entering the tank (a very good thing for the tank). Rapid depressurization will cause some condensation in the vented air even with the after-cooler. The real draw in using an after-cooler is keeping water out of your air when the pump is running as in a long CNC plasma cutting session - lots of parts on a 4x8 plate for instance. The air is back to ambient once it hits the tank and even with the pump running you have much less water for a desiccant dryer or even a refrigerant dryer to deal with. Good stuff for your consumables life and for cut quality. And if you use PEX lines like I did, you'll not see the degradation caused by excessive air temps.


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## jwmelvin (Aug 28, 2021)

Looks great. I’ve been collecting parts to do something similar. Inspiration indeed.


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## Firstram (Aug 28, 2021)

After coolers work incredibly well. I used a Hayden 1299 dual pass oil cooler with a 220 volt muffin fan and high temp hoses. Between the cooler and the tank I have a 3/4" water separator and 10 micron coalescing filter, both self draining. The volume of water pulled out of the air before it gets to the tank makes me warm and fuzzy. This is a fairly expensive setup but it's compact, turns itself on/off and it silently does its job with no input from me.






I put together a point of use filter as well, Coalescing filter, 3 quart desiccant, charcoal filter and pressure reg. It sits on the plasma but I left it portable if I need to spray paint or lacquer.


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## MtnBiker (Aug 28, 2021)

Firstram said:


> After coolers work incredibly well. I used a Hayden 1299 dual pass oil cooler with a 220 volt muffin fan and high temp hoses. Between the cooler and the tank I have a 3/4" water separator and 10 micron coalescing filter, both self draining. The volume of water pulled out of the air before it gets to the tank makes me warm and fuzzy. This is a fairly expensive setup but it's compact, turns itself on/off and it silently does its job with no input from me.
> View attachment 376437
> 
> 
> ...


Awesome setup! Love the point of use/portable concept.


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## Firstram (Aug 28, 2021)

MtnBiker said:


> Awesome setup! Love the point of use/portable concept.


Thanks, it seemed like a waste to lock it in somewhere and there's really no reason to "polish" all the air in the shop either. Your cooler will strip sooo much water out, the non sensitive stuff will be just fine. I have a 2nd 80 gallon tank at the other end of the shop that never gets drained, out of sight out of mind. At the end of the last show after using it for 2 months (June and July in Atlanta) it was totally dry!


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## mmcmdl (Aug 28, 2021)

My company may have to take notes from you guys . We have 23 IR and Atlas compressors thruout the plant , after coolers , dryers , drain alls , oil / water seperators and more coalescing filters than you can shake a stick at and we STILL get water in our lines . Good thing is , we make the filters in our plant ! 

We have two completely different air systems going on also . HP plant air and 28 PSI " heated air " 800 degrees . This may be the cause of some of the problems . We have engineers coming in next month to try and diagnose our issues .


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## Firstram (Aug 28, 2021)

When you mentioned they were blowing hot air at you for all these years, I didn't realize it was that bad.


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## mmcmdl (Aug 28, 2021)

That's a good one Wes !


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## benmychree (Aug 28, 2021)

Talk about hot air, where I used to work at Kaiser Steel, they used a whole lot of air throughout the plant and had a central compressor plant with 5, I think 125 HP IR horizontal double acting compressors 14" bore and a 175 HP Sullivan horiz/vert double acting two stage compressor, a real antique driven by a open frame synchronous motor and 24" wide flat leather endless belt; anyway, the exit air was so hot, that occasionally a fire would get started in the air lines, not an easy thing to put out while still running the plant.


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## fixit (Aug 29, 2021)

benmychree said:


> Talk about hot air, where I used to work at Kaiser Steel, they used a whole lot of air throughout the plant and had a central compressor plant with 5, I think 125 HP IR horizontal double acting compressors 14" bore and a 175 HP Sullivan horiz/vert double acting two stage compressor, a real antique driven by a open frame synchronous motor and 24" wide flat leather endless belt; anyway, the exit air was so hot, that occasionally a fire would get started in the air lines, not an easy thing to put out while still running the plant.


I was in the glass container industry. We normally had 3500 hp of air compressors online all the time.


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## MtnBiker (Aug 29, 2021)

I'm starting to feel inadequate with my puny 5hp compressor.


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## MtnBiker (Aug 29, 2021)

mmcmdl said:


> My company may have to take notes from you guys . We have 23 IR and Atlas compressors thruout the plant , after coolers , dryers , drain alls , oil / water seperators and more coalescing filters than you can shake a stick at and we STILL get water in our lines . Good thing is , we make the filters in our plant !
> 
> We have two completely different air systems going on also . HP plant air and 28 PSI " heated air " 800 degrees . This may be the cause of some of the problems . We have engineers coming in next month to try and diagnose our issues .


Don't pretend any special knowledge on the subject - but the 800 degree air at only 28 PSI can hold a LOT of vapor in suspension. I'd imagine it would be almost impossible to filter (the separators torture the air to try to convert vapor to larger droplets that can be filtered or dropped into the filter bowl).


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## Larry$ (Aug 29, 2021)

Getting the water out is one of those things you pay for up front or down the road. An air to air cooler helps but you need additional drying. As air is used it cools from expansion. Cool air holds less moisture than warmer air so you get condensation at point of use if the air hasn't been dried enough. Change desiccant often. It is usually available with a color change ingredient to show when it needs changing. Refrigerated driers cost more up front but don't take as much maintenance. They are better for shops for continuous air use. Big desiccant self regenerating driers are available.


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## Firstram (Aug 29, 2021)

MtnBiker said:


> I'm starting to feel inadequate with my puny 5hp compressor.


Shouldn't, if it does what you need, it's perfect. Enjoy your dry air!


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## rabler (Aug 29, 2021)

I've added this to my list of projects.  Thanks for the idea!


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## MtnBiker (Aug 29, 2021)

Firstram said:


> Shouldn't, if it does what you need, it's perfect. Enjoy your dry air!


Thanks for trying...but I won't be truly satisfied until at least 100 HP of compressor power. I feel like 3,500 HP might be overkill for a garage-based side hustle though.


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## MtnBiker (Aug 29, 2021)

Larry$ said:


> Getting the water out is one of those things you pay for up front or down the road. An air to air cooler helps but you need additional drying. As air is used it cools from expansion. Cool air holds less moisture than warmer air so you get condensation at point of use if the air hasn't been dried enough. Change desiccant often. It is usually available with a color change ingredient to show when it needs changing. Refrigerated driers cost more up front but don't take as much maintenance. They are better for shops for continuous air use. Big desiccant self regenerating driers are available.


I hear you - spent some time looking at various commercial solutions just for grins. Big money. As we grow this outfit we'll add capability as needed. For now, we'll be installing a Milton polishing system with a fairly large, for a garage shop anyway, 2 quart desiccant dryer.




I may put an additional Motor Guard filter at point of use. We'll see how things work out with the CNC plasma.

Who knows, maybe we get big enough to buy one of these auto-regenerating desiccant dryers someday:


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## Firstram (Aug 29, 2021)

MtnBiker said:


> Thanks for trying...but I won't be truly satisfied until at least 100 HP of compressor power. I feel like 3,500 HP might be overkill for a garage-based side hustle though.


You could set up a small Indoor Skydiving Source as a side side hustle!
When I retire I'll have to downsize my compressor to something home shop sized. 100 amps won't run my 65 amp plasma and start this one.


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## MtnBiker (Aug 29, 2021)

So here is some technical background that most will find boring. But just in case - I've done a little more homework. Consider the following:


Let's compress 8 cubic feet of air down to 1 cubic foot (about 100 PSI).
Compression makes a lot of heat which allows air to store a lot more water as vapor.
Once cooled back to ambient, that compressed air will only hold about 1/8th as much water vapor.
So 7/8ths of that incoming vapor in the air will have condensed to liquid water (the reason you drain your tank).
Regardless of whether you have an after-cooler or not, the now ambient temperature air in both scenarios will be at 100% humidity. Really.
Per the point above - with or without an after-cooler, if ambient temp air comes out of your tank there is an equal amount of water vapor.
With an after-cooler you'll remove most of the liquid water. That's good - keeps the tank from rusting (and going all JATO in your shop).
If you leave your tank pressurized, drain it regularly and only use it to run a nail gun, an after-cooler won't buy you much.
However:

Let's say you don't keep your compressor pressurized all the time. And you fire it up right before you use compressed air.
Or let's say that you do long runs on a CNC plasma, sand-blaster, paint job, die grinding.
You'll add or start replacing all that nice cool, but 100% relative humidity air, with very hot, very saturated air that carries about 14X more water vapor at 150 PSI.
An after-cooler will give you stable outlet temperatures and LOTS less water to filter downstream.
A downstream coalescing filter / water separator will not get overloaded so quickly sending water through the line.
If you use them, your desiccant dryer will thank you (and last way longer).
If you use a refrigerant dryer you'll get much better results.
Industrial applications need after-coolers because the compressors are running all the time. If you are using compressed air with your pump running you should have an after-cooler. If your pump rarely if ever runs when you are using your compressor and you have an automatic tank drain you might not need an after-cooler.

If interested, this is a pretty good deep dive:


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## MERLIncMan (Sep 19, 2021)

MtnBiker said:


> I hear you - spent some time looking at various commercial solutions just for grins. Big money. As we grow this outfit we'll add capability as needed. For now, we'll be installing a Milton polishing system with a fairly large, for a garage shop anyway, 2 quart desiccant dryer.
> 
> View attachment 376602
> 
> ...


Here ya go brother!

You got me brain doing things, so Google found this little guy.









						MDH3-AHE Mini Regenerative Desiccant Dryer, 1.1 SCFM @ 100 PSIG, 115VAC
					

AVP is a leading provider of compressed air dryers, Laboratory Air Compressors, air compressors, natural gas dehydrators & equipment for removing water vapor from compressed air & gas.




					shop.airvacuumprocess.com
				




Not as neat as a home-built, but if you pay yourself by the hour, it might make sense.

Oh, the plots and the schemes!


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## MtnBiker (Sep 19, 2021)

MERLIncMan said:


> Here ya go brother!
> 
> You got me brain doing things, so Google found this little guy.
> 
> ...


Well...at 1.1 scfm it is a little "airbrush painting" oriented I think.


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## MERLIncMan (Sep 19, 2021)

MtnBiker said:


> Well...at 1.1 scfm it is a little "airbrush painting" oriented I think.


Yeah, I thought so too - but my brain doesn't care!

It only sees an obtainable gizmo for sucking water from air!

Also, for about $600 more, they have other models that do more SCFM at lower PSI.

Must be some kinda math here.


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