I am trying to build a budget air dryer/after cooler, the type that you run pipe up and down your wall to cool it and put drains in the bottom. I am trying to do this for as little of an investment as possible, I'm sure you are wondering how budget and stainless work together. I have access to free stainless pipe at work that is less than perfect and piles of extra fittings from past jobs, so I could build it for next to nothing. I have seen these built from copper which was the original plan, black pipe, aluminum air kits..... The question is, will 1" stainless disperse the heat the same as the other materials? Or at least well enough to work.? I have managed to run all of my air system in my garage in 1"stainless so it would be pretty nice to stick to it if possible. Thanks in advance
Is stainless pipe ok for a compressed air dryer?
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welder4956
Well-known member
The thermal conductivity of copper is much greater than stainless steels, so stainless won't cool near as well as copper. You would need a lot more surface area to achieve the same amount of cooling, maybe 20 times as much.
nadogail
Well-known member
IMHO, Stainless will work just fine for your purpose, the heat dissipation will be less than copper but can be compensated for by adding a greater mass of piping.
Actually, again in my opinion the heat dissipation between the two materials in your application will very probably be negligible or very close to it.
Be careful that your Stainless Piping does not become “Bright Work”.
Actually, again in my opinion the heat dissipation between the two materials in your application will very probably be negligible or very close to it.
Be careful that your Stainless Piping does not become “Bright Work”.
I just came across some old hot water radiant heaters I am going to use from an old house renovation. It is 3/4" copper with aluminum cooling fins. It is not a pretty set up but cheap and effective.
Here is a link to a similar new part to give a visual idea of what it is.
Here is a link to a similar new part to give a visual idea of what it is.
Thanks for the comments/info.
Most of the setups I have seen are 1/2 and some 3/4 copper, this will be 1" so the surface area will be a bit more. I am using this to shoot paint on cars in my garage, if that makes any difference. After this cooler I will have multiple in line filters including a motor guard, small desiccant and a large home made desiccant filter that I will run only when shooting paint, on its own it probably covers my needs. I am honestly hitting the stages of overkill but if I can build this for literally free, I figure why not?
Most of the setups I have seen are 1/2 and some 3/4 copper, this will be 1" so the surface area will be a bit more. I am using this to shoot paint on cars in my garage, if that makes any difference. After this cooler I will have multiple in line filters including a motor guard, small desiccant and a large home made desiccant filter that I will run only when shooting paint, on its own it probably covers my needs. I am honestly hitting the stages of overkill but if I can build this for literally free, I figure why not?
racecougar
Well-known member
The surface area of 1" tubing is larger than that of 1/2", sure, but not relative to the volume of air within the tubing. As the diameter increases, that ratio (surface area/volume) decreases.
Will it work? Sure, it will allow for some heat dissipation. It won't shed heat nearly as well as copper though. As you said above though, if you're able to do it for free, why not?
Will it work? Sure, it will allow for some heat dissipation. It won't shed heat nearly as well as copper though. As you said above though, if you're able to do it for free, why not?
Innovate1
Well-known member
I would think that since this is a somewhat thin tube the change in conductivity of the metal would not matter much since it is still much better than the air next to it that has to carry the heat away. Theoretically it will make a difference but not practically. Theory and reality are only thoeretically related. 
racecougar
Well-known member
That's a good point. We haven't heard what the wall thickness of the tubing is.
racecougar
Well-known member
Yeah, that doesn't help matters.
That said, if nothing else, what you're doing will provide more distance for the water to drop out of suspension. It'll still reject some heat, but not like type L copper would.
That said, if nothing else, what you're doing will provide more distance for the water to drop out of suspension. It'll still reject some heat, but not like type L copper would.
hmmm, maybe I should just pony up the cash and do it in copper. Like everyone else, I am trying to save a few bucks where I can. But if I am not doing much to help then I am not sure it is worth doing in stainless. 4 sticks of 3/4x10' copper is going to run me around 175 locally and then add fittings
racecougar
Well-known member
Have you shot any paint as-is yet? Is your compressor drawing conditioned air or are you at the whim of nature?
Another idea, which has the potential to offer more heat rejection, is to use an actual heat exchanger. The Derale 15300 is a commonly used unit for this.
Another idea, which has the potential to offer more heat rejection, is to use an actual heat exchanger. The Derale 15300 is a commonly used unit for this.
A fan is certainly a option and I already have one that I had thought about using for this regardless of the material.
I have not shot paint yet, still getting setup. I have though about using a heat exchanger like that, I actually think I have a spare one off a transmission laying around. From the research I have done, the method of running 40-50 feet of line up and down the wall works very well. I was just hoping to save a few bucks with free parts, I could build the entire thing from stainless for free, down to stainless valves.
I have not shot paint yet, still getting setup. I have though about using a heat exchanger like that, I actually think I have a spare one off a transmission laying around. From the research I have done, the method of running 40-50 feet of line up and down the wall works very well. I was just hoping to save a few bucks with free parts, I could build the entire thing from stainless for free, down to stainless valves.
pcmeiners
Well-known member
Thermal conductivity and thermal emmissivity are two different characteristic of metal, as such copper conducts heat better than Stainless but steel is a good radiator of heat, as good as copper if it is oxidized or has a dark color. If stainless is used,anodized it to a dark color at which point it will radiate heat as well as copper, a bit less due to copper's better conductance.
https://www.flukeprocessinstruments...-center/infrared-technology/emissivity-metals.
That said it would be a hell of a lot easier using copper pipe, and the more copper is oxidized the better it radiates heat; it is actually a rather poor radiator when it is new and not tarnished.
https://www.flukeprocessinstruments...-center/infrared-technology/emissivity-metals.
That said it would be a hell of a lot easier using copper pipe, and the more copper is oxidized the better it radiates heat; it is actually a rather poor radiator when it is new and not tarnished.
racecougar
Well-known member
The thermal diffusivity of copper is over 26 times that of stainless. The additional wall thickness of the stainless that the OP has available doesn't help matters.
As said above, if it's free, why not? Just don't expect it to perform as well as copper would.
As said above, if it's free, why not? Just don't expect it to perform as well as copper would.
chevy3100truck
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as someone who deals with heat exchangers daily (manufacturers rep/supplier), there is definitely some "interesting" advice listed here....... I'd suggest to ignore the much of it (ie. the comments about needing 20 times as much stainless vs. copper......)
not sure how much pressure that will hold, it's normally thin walled as the water pressure is around 15psi
metlmunchr
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If you use the pressure rating and wall thickness of M copper to calculate its stress at the rated pressure, and then use that stress and the wall thickness of copper fin tube, you'll get a max pressure in the range of 400 psi for the fin tube. This is based on values for 3/4" M copper and 3/4" fin tube. Per foot, the fin tube will shed about 6X the heat as compared to bare M copper. The fin tube has to be mounted horizontally for max heat transfer as that will allow max temperature induced air flow across the fins.
racecougar
Well-known member
I'd suggest speaking to the engineers that actually design the heat exchangers.
Joe Reed
Well-known member
The material is free. I'd do it and see how it works. If it's not acceptable all you've wasted is time...
Monza Harry
Well-known member
There are ways to improve the thermal conductivity. You want "turbulent" air flow not "laminar" air flow. There are things available for schedule 40 tubing but not in lengths and stainless friendly materials. But a home fashioned version could be built from stainless shim stock. https://cdn.genalpha.com/2/marketing-banner/category/296/202207260615/brass baffles category.jpg
Buy some thin [less than say 0.010"] and make your own(?), also at 1" sch40 your air speed with even a 5HP compressor running at 1/2 juice will be pretty low allowing the air to cool better, you could also run 2 (or more) parallel lines to double the surface area and halve the speed, since it seem that you have a good supply, additional could be added if sufficient cooling isn't achieved. Place these between a couple of vertical planes [create a duct] and that fan will help even more. Pricing makes this an attractive option many of us don't have! Use your thermal [IR] gun to determine actual delta T for understanding your success [or lack there of] and adjust accordingly. There are even more improvements you could come up with. Harry
Buy some thin [less than say 0.010"] and make your own(?), also at 1" sch40 your air speed with even a 5HP compressor running at 1/2 juice will be pretty low allowing the air to cool better, you could also run 2 (or more) parallel lines to double the surface area and halve the speed, since it seem that you have a good supply, additional could be added if sufficient cooling isn't achieved. Place these between a couple of vertical planes [create a duct] and that fan will help even more. Pricing makes this an attractive option many of us don't have! Use your thermal [IR] gun to determine actual delta T for understanding your success [or lack there of] and adjust accordingly. There are even more improvements you could come up with. Harry
Here is a picture of the almost finished product, I still want a larger line coming off the compressor, it is only 1/2" and has carbon fittings, but it was free. Somehow I ended up running my entire air system in 1" stainless, I did not intend to, with the free materials from work and buying maybe another 150-200 in random fittings. I probably have at most 300 dollars in the entire system with the cooler and 4 air drops that are valved off with high flow fittings to the air hose and filters. I was lucky and got the milton air filters as hand me downs from work, they needed some work put into them. They were going in the trash since they cost more in labor to rebuild then it is to buy new. Also attached is a mock up of my desiccant filter that will run only on my line to the paint gun, it will also have a motor guard filter after that just to be 150% sure of clean dry air. I have about 40 bucks in the desiccant before adding another 40 dollars for silica beads, mostly all from the left over bin at work besides the site glass. I am fortunate as hell to have access to left over materials. There is roughly 100 feet of pipe before my paint gun, the air itself has roughly 40-45 feet and may be thick wall but I think it will be fine, there is another 60ish feet in thin wall pipe that we used pro press fittings on. I personally think this is complete over kill for what I am doing, but for the little amount that I have invested, why not? If for some reason the dryer is not working as well as I need it to, I will add fans to it.
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Tynee
Well-known member
Have you thought about plumbing this in between the outlet of the compressor and the inlet of the tank? It seems like it would be nice to have dry air in the tank so you don't have to worry about corrosion in there. You'd still want filtration on the tank outlet. Just an idea to consider.
ETA: On second thought, you may not get enough cooling to get liquids to condense before the air hits the tank? IDK...
ETA: On second thought, you may not get enough cooling to get liquids to condense before the air hits the tank? IDK...
metalmagpie
Well-known member
1. Gather up a big pile of free stainless pipe and fittings.
2. Sell them and buy a small pile of just the copper pipe and fittings you need.
3. Pocket the difference.
2. Sell them and buy a small pile of just the copper pipe and fittings you need.
3. Pocket the difference.
yeah this is silly talk. hot copper is still hot copper
. you need to dissipate the heat! I'd bet lunch that a $10 fan on a pile of stainless will do more cooling than no fan on a pile of copper 1/20th the size.
my compressor has what looks like a muffin fan sitting on an 10" x 10" aluminum HX, and it does 90% of the water removal. big delta T from inlet (can't touch) to outlet (ambient +20F).
My company is generous enough to let me use stuff for personal use, I would get fired if I took their materials and sold them.
It's something like 3' higher than any spot horizontal within 10'