# Air Compressor Line Water Filter Recommendations - Paint Spraying



## mark sr (Jun 13, 2017)

First thing, how often do you drain the water out of the bottom of the air tank?

I used to live in humid fla where moisture in compressed air was a big problem. Here in northeast tenn moisture is barely a problem.

IMO the cheap air/moisture filters work just as well as the more expensive ones. They work best the further they are from the air compressor.


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## SeniorSitizen (Sep 10, 2012)

Sometimes we get water and sometimes we don't.

To completely avoid a water filter consider using this handy calculator and the airport link for AZ ( choose AZ in link ) in conjunction with your painting projects. In Phoenix it shouldn't be a problem choosing a relative humidity in the 10% range most any time of day during warm weather. On 5-6-18 at about 5:00 AM the RH was 9% in Phoenix . Example: at 85° and the RH being 10% the dew point will be 23°. I doubt moisture will accumulate in your compressor tank or hose with a DP of 23°.

http://dpcalc.org/

http://www.usairnet.com/weather/maps/current/florida/temperature/


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## jeremyjohnolson (May 6, 2018)

mark sr said:


> First thing, how often do you drain the water out of the bottom of the air tank?
> 
> I used to live in humid fla where moisture in compressed air was a big problem. Here in northeast tenn moisture is barely a problem.
> 
> IMO the cheap air/moisture filters work just as well as the more expensive ones. They work best the further they are from the air compressor.


I use to drain it once in a blue moon, but now I drain it after every use and just leave the drain valve open until the next use. I never get much water out of it, even when I only drained it rarely, I would only see some mist shoot out but never much water at all.

Would it be good to have one cheap one right at the first part of the hose by the tank and another one connected to my spray gun?


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## jeremyjohnolson (May 6, 2018)

SeniorSitizen said:


> Sometimes we get water and sometimes we don't.
> 
> To completely avoid a water filter consider using this handy calculator and the airport link for AZ ( choose AZ in link ) in conjunction with your painting projects. In Phoenix it shouldn't be a problem choosing a relative humidity in the 10% range most any time of day during warm weather. On 5-6-18 at about 5:00 AM the RH was 9% in Phoenix . Example: at 85° and the RH being 10% the dew point will be 23°. I doubt moisture will accumulate in your compressor tank or hose with a DP of 23°.
> 
> ...


That's a good point. If I learned more about how and why the moisture is created I might be able to just avoid it altogether. Would I be better, worse off, or indifferent if I ran the air compressor in the house and hosed the air out to the garage (house is cool, garage is hot). I have to check if it's safe to run the air compressor in the house, I don't see why not, if it's safe to run in the enclosed garage, my house is just as vented if not more so than the garage.


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## Gregsoldtruck79 (Dec 21, 2017)

As you know by now, what you need is called desiccant in line air dryers (not the big electric dryers) . I know you are not using the same air equipment as I used to have, but spray painting with air is all the same principle basically, regardless of the size of the air compressor. We have to have clean, dry, uncontaminated air to not spoil our spray job for quality finishes. 

When I painted my old truck I set up a 3 stage filter system for my 3 Sata HLVP spray guns. The "dryer" was the largest unit to the extreme right in the messy garage pic and the last component in the line... right at my air hose connection outlet. 

When air gets compressed it heats up and hits the cool piping and produces moisture. So when I ran my 3/4 in. black pipe air lines on my garage ceiling, I ran them to drain back towards my SpeedAire 5 HP. V twin compressor with its 80 gallon tank, where I drained it daily.

At my filter station/outlet where I plugged my air hose in, I put a drip leg on my piping and a ball valve at the floor where I always drained it*, before* I ever started spraying the VERY expensive BC/CC automotive products.

I never had one water droplet in my paint. Here is a link to a filter not quite as large as mine, but my compressor was 12 CFM unit. The "dryers" should be matched to the expected CFM output of your compressor. And the desiccant material will turn colors when they need replacing if I recall correctly, but its been a long time since I painted that old truck.  

https://www.amazon.com/Compressed-Filter-Desiccant-Moisture-Separator/dp/B06XYW2LDC/ref=sr_1_19?ie=UTF8&qid=1525631514&sr=8-19&keywords=air+dryers+for+compressors


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## SeniorSitizen (Sep 10, 2012)

jeremyjohnolson said:


> If I learned more about how and why the moisture is created I might be able to just avoid it altogether. Would I be better, worse off, or indifferent if I ran the air compressor in the house and hosed the air out to the garage (house is cool, garage is hot).
> ***************************************************
> Learning how and why the formation of dew is usually a good plan. Consider researching dew point and its relationship with ambient air temperature and relative humidity.
> 
> ...


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## ron45 (Feb 25, 2014)

Harbor Freight has a couple, but I purchased this about 4 years ago. It has work great.

https://www.harborfreight.com/industrial-air-filter-regulator-68247.html


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## mark sr (Jun 13, 2017)

I have 2 HF filters like the one pictured above. Purchased about 25 yrs ago and still work fine although I did knock the glass out of the gauge on one of them several yrs ago.


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## SeniorSitizen (Sep 10, 2012)

jeremyjohnolson said:


> That's a good point. If I learned more about how and why the moisture is created I might be able to just avoid it altogether.


 usairnet is showing us all we need to know at present and you can learn more if you like but we need to paint now.:smile:

With present dew point conditions you could paint without moisture problems anywhere in the state well into the night and probably all night. Higher elevations such as Flagstaff would be the only locations to watch maybe a little more closely some days but for what we see now a second coat may be applied in about 3.1 minutes.:vs_laugh:


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