If anyone has any experience with air compressors, I'd like some help/advice regarding the following:

I have a 30 gallon Craftsman compressor (built in 2008). 8.6/6.4 CFM @ 40/90 psi. I have a moisture filter before the hose hook-up.

1. RUSTY WATER IN THE TANK
When I drain the tank, there is always rusty water, maybe 1/4 cup or so. I know this is normal, but how much is supposed to come out? Is there an standard/typical amount that is normal?

2. WATER IN THE HOSE
I also get air in the hose that comes out whenever I use air tools. I get a few drops every few minutes. When I bleed the moisture filter, no moisture comes out.

3. IN-LINE FILTER
I'm thinking of getting another in-line moisture filter. I will be painting some parts soon and want to make sure that I don't spray water with the paint. What do I look for in a decent, in-line moisture filter?

Thanks!

I just picked up an auto drain valve for my compressor, about $30 on Amazon. You can wire it to your electrical supply so it runs when your compressor is on. I think cheap insurance to save the compressor.
Invest in a couple good filters, water/oil a coalescing type. I know if you are painting this is really important. You can even try the cheaper HF kind, some people have had good luck with these. I have a good Snap-On that came with my unit but you do need to service them from time to time.

Good luck!

One of the effects of compressing the air is to cause the precipitation of water. Moisture filters keep the air from effecting your paint if you are spraying but most guys and shops, when they power down the compressor, bleed the air and drain the tank. You shouldn't be getting a quarter cup unless you live somewhere really humid and work your compressor for long hours.

Would this work:
https://www.amazon.com/TCP-Global-Filter-pa...ilter&psc=1

Is this what you are referring to? It's not $30, though:
https://www.amazon.com/Electronic-Automatic...+air+compressor

Air is like a sponge, compress it and water vapor has no space to reside so it falls out, this is normal. The more ambient humidity and more air you use, the more water you will get. The air compressor isn't making water from hydrogen and oxygen.

Your current moisture filter is becoming overwhelmed, you might need to run 2 in series or a larger capacity one. Better moisture filters have an auto float drain and are worth the extra $. A second tank and / or hard piped shop with drain legs can be helpful as well.

If the line from the compressor pump to tank is close to the air outlet, water does not have a chance to fall out of the air and will be carried over to your moisture filter during times of high air use.

If you get a timer style auto tank drain ,while inexpensive, they waste air as they are always in operation even if you are not using any air ( RE: they will drain even if there isn't any water. ) . The better ones ( $ ) drain only when there is water and won't let any air be lost in the process.

Compressed air is an expensive 4th utility ( Electricity, water, nat gas , air ) so fix those system leaks if you have any!

https://www.amazon.com/gp/product/B015IY9VJ...=UTF8&psc=1

This is the unit I purchased.
I set it to run for a couple seconds every hour when the compressor is on. I have a 60 gal unit so a few seconds of open air is not a big deal to me.

The filter you selected is all right for use at the source. Get yourself a wall mount unit too:

http://www.tptools.com/RTI-Mini-Desiccant-...6.html?b=d*8089

Obviously this is expensive for most people but I think worth the cost for clean air.

DM-2000 makes some very good points in his post as does ConeDodger.

Thanks for the info, but the links don't work for me (DNS Error). If you give me more info, maybe I can just find it.

Thanks for the info!

The filter is located right at the exit from the tank. I have a short piece of hose I can use to relocate the filter farther out, and also add another filter. I might add an in-line filter as well. Still looking into the tank drain.

Link is fixed.

I would be inclined to look for a replacement,if your receiver is rusty not much need to proceed further and it will become a safety hazard,auto drain valves are great and work well as stated.
Go for the biggest unit you can afford and fit a water separator and autodrain,make sure you use a minimum of plastic hose as it helps little with moisture problems.
Go for a 10 to 12 cfm unit and you can do pretty all you may need,if you need more capacity add a remote receiver for light sand blasting for example.
My previous experience was with 2 large dual stage intercooled 3 phase compressors making 30 bar pressure max running 2 very large air start tanks....huge amounts of water made like you wouldn't believe.

while not convenient, I used two bags of ice at the lowest point of my hose and routed the hose upward after the ice. drain the hose after each painting. you could coil your hose in a large bucket and place ice over the coil.
here are a couple possibilities, one for at the input to the spray gun and the other, while expensive should cure the problem.

at the gun Click to view attachment

expensive Click to view attachment

images from eastwood

I used the "at the gun" and the ice and cured my water problem.
I also kept an eye on the humidity level and planned my painting accordingly.

From what I've seen, most compressor tanks are not painted inside so rusty water is inevitable.




Working in a power plant that uses piston engines running on natural gas? ( Or maybe turbines on nat gas )

You are welcome.

To clarify a small point. The compressor pump to tank entry vs where you get the air out is the distance I was speaking of. This distance is fixed unless you make major design changes.

Air needs some settling / cooling time otherwise the moisture will be carried over to the outlet and past the moisture filter. Also, once water has fallen out of air in the tank, it won't get picked back up to any great degree but is still needs to be drained.

Take a look at best practices for laying out a shop air piping system. If you can mimic that even on a small scale it will help.

A car rad won't hold up to the pressure. This type of system this more like an hydraulic oil cooler or even a turbo air to air intercooler.

Got it, thanks!

I got another filter, so I have 2 of them. I'll have to see how well they work before deciding if I want to spend $190 on the one in the link. I'm assuming it works really well!

It seems from more research that I've done that the moisture filter needs to be about 25' away from the tank to let the water vapor cool enough so the filter can take it out easier. The ice trick works as well. Some have suggested mounting the line to the water filter above the tank so the water goes back into the tank.

I don't want to run line all over my garage, so think a possible solution is to attach a 25' hose to the tank and coil it next to it, then attach this to the air filters I have mounted on the wall, then have my working hose off of this. I also got a disposable in-line dryer.

Thanks to all for your input and advice. Once I get this all set up, I'll run some tools and try to remember to report back.

Do you have a picture of the tank drain valve mounted? I'm having a hard time visualizing how this is mounted.

that's what I did. It works well

Steel air pipe helps, but it's a hassle to install, and ideally you'd either treat the inside or get galvanized.

And never ever use PVC or other hard plastic pipe. Oil carried over from the compressor will deteriorate the plastic causing it to burst. If a pipe carrying water bursts, it will just leak. If a pipe carrying air bursts, the expanding air will propel plastic pieces long distances.

Running a fan across the tank will help cool things. It is still good to have a dryer at the tank and a second one down stream. In your situation I'd string some ( 10 ft would be fine ) hose across the shop to the 2nd dryer. With a dryer at the tank outlet, I would not be concerned about having the hose run down hill.

Also, the only time water would run down hill is when you are not using air.

Lot of good posts here. Good info on what works for others who may be in areas with more/less humidity than other places.

In the small garage I like to keep things simple. No room for an air drier (condenser) so I let gravity work for me and three quality separator/ filters. (Sharp and two Miltons -all auto drain)

If you have a lot of moisture in ambient air it will enter the compressor and tank. Add heat from the pump and it creates its own atmosphere like a jungle.

1/4 cup of carrot juice coming out of the tank in a garage compressor is nothing. Don't sweat it. You should see the junk that comes out of a full service shop with multiple alternating compressors running all day long.

Like any tool take care of it. Drain the tank before and after use. When I bleed air down I open the petcock and let air force any remaining moisture out, be done and spook the dogs.

If you place a filter or separator too close to the compressor it just doesn't do much. It needs a little run to cool down and let the vapor return to liquid. Water/oil mix is heavier than air so I run my separator/ filters down pretty low again using gravity. Then I go up to my hose reel again using gravity for any moisture getting past the Miltons. I use 3/4 inch hose coming out of the compressor and going up to the hose reel. It slows the air velocity a bit giving a little expansion room and makes a difference. Water does not move up very well and settles at the trap level.

I loose about 3 cfm with the Sharp and two Miltons but never experience an excessive moisture problem at the hose.

For paint and primer I do use a CAM Air desiccant canister but for general use no need for it.

Quality separators/ filters are key. I have used them all from Sharp, IR to Motorguard and DeVillbis. Personally IR and DeVillbis are terrible at moisture removal until you get into the $1000 plus tri and quad module systems.

If you have the room and extra duckets run your lines over the top of the garage and down an opposite wall to your regulator and hose. Have a low settling tube below the regulator level with a drain. If you have room and can afford a secondary storage tank that makes a world of difference in cooling the air charge across the system.

Synthetic oil in the pump makes a big difference also. Its less sticky and does not break down as quickly as dino oil. Seems to not vapor as much which attracts less water molecules.

Regulators and traps mounted right off the tank outlet are also problematic. They seem to contribute to moisture issues down the line to the hose end and are prone to shortened service life. The air is too hot and velocity high where it simply overwhelms and blows moist air right through.

Gravity is your friend with moisture even when comingled with compressed air.
Keeping it down low is easy -just figure out what way works best to keep it low and out of the upper respiratory tract. More expensive or shop systems that use driers are great and those driers are usually mounted at ground level for a reason. Water doesn't like to climb.


Simple and works for a small garage. The separator/ filters are about $500 in expense.

Air we talking about moisture in the tanks or the tools or both? The only way you're going to keep it out of the tank, and the tools without a trap, is to dehumidify the air before it enters the tank. Drain the tank when done and leave the petcock open. You'll remember to close it when the pressure doesn't build.

I agree that water needs gravity and distance to cool down and fall out. I run 3/4" copper pipe to all three outlets, with drains down below on each. I have about 70' of pipe running along the ceiling and down to the outlets in 2-car garage. For painting, I use a Devilbiss desiccant snake hose (~$30) coming out of an HF swirl-pot filter, and then a MotorGuard (model #DD1008) see-through filter at the gun. These MotorGuard filters let you see the desiccant as it turns from blue to pink as they colllect moisture; the little pumpkin-style gun filters only let you know there's a problem after the paint dries. Ask me how I know... the little pumpkins are about $7 each while the MGs are about $15 each. Money well spent.

The instruction manual " drain tank after use " should really read " Drain water after use " There isn't any reason to remove all pressure from the tank between uses.

First of all, thanks to all who contributed. Here's a picture of my set up (the picture is sideways):
Click to view attachment

I used a paint gun with a moisture filter (the "pumpkin" ones) at the gun and this seemed to help.

However, I was using a die grinder (no "pumpkin" filter) and am still getting some moisture. I'm wondering if I need to make more modifications? I'd like to have a system where I get little or no moisture without using a "pumpkin"-style filter. The hose from the tank to the filters on the wall is 25 feet long. Should I lower the whole wall assembly?

Running line all over the garage is not an option for me.

Are the 2 filters possibly too small? They never seem to have any moisture in them. I thought having 25 feet of hose between them and the tank would allow the water to settle out.

Make sure air is flowing in the direction of the arrow on the filters. ( check both )