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Air Compressor Moisture mitigation

equiprx

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I have a machinery shed which housed our central vacuum system and my compressor.
There has always been water in the system.
I have a water separator with particle filter that doesn't seem t do anything.
Every time I open the drain there is water in it.
Not only that but water is making it's way through the hose reel into the tools.
I have been doing a bit of research.
I read that I need a minimum of 20 feet separating the compressor from the outlet.
That is of course impossible but someone suggested using an air conditioner condenser.
Has anyone tried that and how did you go about assembling it in the system.
Did you use a cooling fan and how did you wire it up?
I'm thinking of mounting it relatively flat, is that a problem?
This is an experiment so I can't afford to just waltz in to the dealer and order it.
Any easy suggestions on the easiest way to find one?
 

LarryK

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I have water seperators on two areas on mine. Seems like they are supposed to drain with no pressure, but never see spots on the floor. Main drain always has something. I use the ball filters on my spray gun when painting and change each time I use it. Seems to work, don't see spots on paint.
 

Jerry

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my brother uses this:
I use two water separators, and then 3 filters after that. Still get some water through if you don't bleed the system everyday
 

Grantura_MKI

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I have a dryer. It is fitted in the rafters of the shop well above the compressor. Water will need to run up hill to get into the unit. I drain the compressor regularly. Have two water separators, one at the main hose real and one at the cabinet blaster. Been that way for years and no problems with paint or air tools.
 

Madflyer

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I have a Y at the out let one side to air tires etc and a separator for tool and paint but I live in Nevada we do not get much humidity. Maybe keeping it in a warm box or cover. MF
 

DavidApp

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I live in Georgia so during the summer we get days with very high humidity.
I ran about 60' of copper pipe in my shop at celling height ending in a sideways "T". The bottom leg goes to a drain valve at bench height them the upper leg feeds my air system.
I also have a water trap at the outlet from the compressor and at the hose connection at the wall.
I do get a good bit of water at my drain valve when spraying or sand blasting.

David
Air pipe setup 2.jpg
 

PC

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....... I have a water separator with particle filter that doesn't seem t do anything......
Where is it located in the system?

...... I read that I need a minimum of 20 feet separating the compressor from the outlet......
Unless whoever it was explained that based on physics, I'd ignore it. Concentrate on what's actually going on.

...... someone suggested using an air conditioner condenser.
Has anyone tried that and how did you go about assembling it in the system.
Did you use a cooling fan and how did you wire it up?
I'm thinking of mounting it relatively flat, is that a problem?.....
Not an inherently bad idea, but you'd need to be sure you were getting one with the right pressure ratings, tubing cross-section, etc. Otherwise you might be obstructing flow, springing leaks, exploding... A fan could simply be wired to run whenever the motor is running. You could also get fancy and have a timed relay that keeps it running for some time after the motor kicks off. I wouldn't lay it flat. Water flows downhill. If there's no specific downhill path it will collect randomly and unpredictably wherever.


Before trying a band-aid fix, I'd suggest looking at the whole system and trying to figure out what's going on, where. From there coming up with a solution should be fairly straightforward.
 

Popeye

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Good conversation. Having spent 20+ years in the compression business, water in compressed air is a common problem. When you raise the pressure of air, some of the water may be "squeezed" out. If you live in a humid climate, water in air is a bigger issue (Florida, Georgia, etc. vs. Arizona and New Mexico). Folks in Arizona do not have the same problems! Compressing air also makes it hot. So the air exiting the compressor is (1) hot, and (2) has the same moisture content as the air going in, but (usually) all in vapor form. When the air cools, like when it runs through a tool, the water condenses, and you have water in the air - and rusty tools, poor paint, etc. Depending on what you want to do with the air, the acceptable amount of moisture changes. Paint needs very dry air (refrigerated dryer best). Air tools can stand some moisture, as long as you run oil through them regularly.

To remove the water, you need to (1) cool the compressed air, and (2) separate the now liquid water from the air.

Driers are nice - but expensive and require another "device" taking up space in the shop. Typical electric driers are basically a refrigerator, and a centrifuge at the exit, such that the liquid water is "spun" out of the cooled air.

The "rule of thumb" of 20 feet is to allow the air to cool. I can't say if 20 feet is or is not enough... but basically if you can get the air to slow down (big pipe), and exchange heat with the surrounding (cool) air (metal/copper pipe), some of the moisture will condense to liquid. In my garage, I have about 40' of iron pipe, run back and forth on the wall - similar to DavidApp. At the end, I put a T, air goes up and the water goes down. It is important to slope the pipe such that liquid moisture runs back to the compressor.

Important:
1. Drain your compressor tank frequently. I have a solenoid valve that drains the bottom for a few seconds every few minutes. There is a lot of energy in a compressed air tank; you don't want a rusty area blowing out.
2. My opinion: do not use PVC pipe for compressed air. The pipe is plenty strong, but when it ages it gets brittle, and should you drop a large hammer on it, there could be shards of plastic flying around. I suppose you could use PVC if you shield the pipe. OSHA does not allow PVC.
3. Make sure anything you add tot he system, e.g. refrigerator coils, is rated for pressure.
4. Use a particulate filter between cast iron pipe and your tools.
 

George_H

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I agree with the above with one exception. I have had a lot of issues with cast iron pipe with air systems. They rust and clog up everything. I now use copper and brass for everything. NEVER pvc.
 

Popeye

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I agree with the above with one exception. I have had a lot of issues with cast iron pipe with air systems. They rust and clog up everything. I now use copper and brass for everything. NEVER pvc.
You are right; cast iron rusts and clogs. I used it because is is cheap, safe, and easy to re-configure as needs change (I'm on my third garage, and it helps when parts are screwed together). As a casual user, I don't get too much clogging due to rust.

Having said that were I to do it again, I would use copper (the high pressure version).
 

George_H

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I'm also a big fan of the automatic solenoid drains. they are cheap. I have ruined a tank after not draining often enough.
 

2liter4cyl

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when doing lots of sand blasting,(a great expansion valve it is), I bought a 20' coil of 1/2' CU tubing, put it at exit from the compressor, submerged it in a tub of water, and exited into a big water trap. The whole idea to drop the air temp below the dew point. depending on your location, change water as it warms up. Ice added helps to change the dew point. Use your imagination .

Let
 
OP
equiprx

equiprx

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If I could get the air coming out of the hose dry, I might try media blasting again or even painting.
I have room above the compressor where I'm thinking of installing a chiller.
My guess is that I should run the hot air coming out of the pump, directly into the chiller.
I can have some big bore pipe exiting the chiller with a water trap and a drain at the bottom.
Somewhere along the pipe I can 'T' off there with a narrower line direct to the tank.
My HF automatic drain at the bottom of the tank is draining only a few drops on restart.
I still get lots of water when I open the manual drain at least daily.
The chillers I have available are basically free.
My space available and budget won't allow long cooling lines.
Please add your comments, advice and criticism.
 

George_H

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Normally the pump goes to the tank, Then come out of the tank to the chiller. Chillers work great, I borrowed one from work when I painted my car. I tryed painting without one... What a disaster.
 

Bayless

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Our shop compressor makes far too much water for painting. I brought my 25 gallon portable from home to paint. It is more than enough for the purpose. In fact it will pretty well keep up with a die grinder but a D/A will bring it down in less than 10 minutes. For some reason, it is breathing the same are as the big one but just doesn't seem to make much if any water. Both have water separators but I rarely get any water from mine when I drain it. Go figure.
 
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equiprx

equiprx

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Normally the pump goes to the tank, Then come out of the tank to the chiller. Chillers work great, I borrowed one from work when I painted my car. I tryed painting without one... What a disaster.
I know how the compressor is normally configured, but the output from the pump is over 250 degrees.
That hot air going into the tank causes the moisture to precipitate out and wind up in my tools.
No amount of draining gets rid of it, that's why I want to condense the water outside of the tank.
 

DavidApp

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Some condenses out in the tank but some remains in the air I presume because the air in the tank is still hot. Bigger tank less problem.
The long length of metal pile before your tool gives te air time to cool and more of the moisture to condense out.
If I did the setup again I would go with 3/4" copper and a longer length.
You could use something like this to get the air cooled down and the water out.
David
 

Popeye

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I know how the compressor is normally configured, but the output from the pump is over 250 degrees.
That hot air going into the tank causes the moisture to precipitate out and wind up in my tools.
No amount of draining gets rid of it, that's why I want to condense the water outside of the tank.
Condensate will form wherever the cooling takes place. Cooling can happen (1) in the tank, (2) in the pipes, (3) in the chiller, or (4) in the tool. An air system should have drains throughout. It does not matter if the system goes from pump to chiller to tank, or from pump to tank to chiller... cooling is needed to remove moisture.

Honestly it does not make much of a difference, pump-chiller-tank or pump-tank-chiller.

In theory, if the system goes pump-tank-chiller, the air will have cooled somewhat in the tank. And some condensate will have "dropped out". The chiller will be able to cool the air to a lower temperature (because it starts colder, and it is easier to cool air than water). The colder air coming out of the chiller means more moisture has been removed. (Dryer air.)

However, as you mention, you are not getting much condensate out of your tank in the current configuration. Air is a pretty good insulator and takes a long time to cool. (I get condensate days after using the compressor*.) For this reason, the difference pump-chiller-tank or pump-tank-chiller does not matter.

In my opinion, it is is easier to go pump-tank-chiller because that is how the compressor and tank are plumbed when you buy them.

Having said all this: The air temperature will drop in the tool as the air expands (PV=nRT). If the air leaving the tool is colder than the air leaving the chiller, you will have additional condensate.


*Safety note: If not using the compressor for a while, it is best to let the condensate valve de-pressurize the compressor tank. The tank takes a long time to cool, and as it cools more moisture will form. (1) if you vent the tank immediately after use, the metal walls of the tank will be hot, the liquid will not condense on the walls. Once it condenses, there will be no air pressure to force the water out - only gravity. (2) if you leave the tank at pressure, water will form as the tank cools and water will pool at the bottom. The air pressure of the tank will forcefully spit out the water. Method 2 gets more water out. Less water = less rust. Less rust = less chance of pinhole (or explosion).
 
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