Increasing CFM in air compressor

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Forum topic by shelly_b posted 02-16-2013 01:27 PM 40402 views 0 times favorited 28 replies Add to Favorites Watch
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850 posts in 2139 days

02-16-2013 01:27 PM

I have a 6 gal PC air compressor. I would like to be able to use it with a spray gun for finishing, but I’m pretty sure the CFM is to low (2.6 @90PSI). I really don’t want to have to wait on it to fill back up, or listen to it run all the time. I saw in a magazine where someone made a really neat air tool station that included a portable air tank(not compressor) that was used as a resevior. Has anyone done this? If so, would a 10gal reserve tank be sufficient enough to run a spray gun that requires around 4.5CFM at 40PSI? Or do I just need to get a bigger compressor, or spray station?

28 replies so far

View Stephenw's profile


273 posts in 2407 days

#1 posted 02-16-2013 01:40 PM

The output of the compressor must exceed the demand of the air tool.

You can get bye with a smaller compressor with tools that are used in short cycles such as impact guns, nail guns, and air ratchets. Continuous demand air tools such as air sanders and paint guns require a compressor that is sized for the tool.

You need a larger compressor.

You could also buy an airless spray gun or a spray gun system that includes it’s own air source.

View DIYaholic's profile


19623 posts in 2697 days

#2 posted 02-16-2013 01:42 PM

I have a 30 gallon oilless compressor, however I have not used it for spraying, so take this with a grain of sand. The manual (& chart on compressor) states that intermittent spray gun use is possible. So, I would say a ten gallon reserve would not be sufficient.
I’m sure others with actual experience will chime in shortly.

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

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2387 posts in 3569 days

#3 posted 02-16-2013 01:44 PM

I don’t think the extra tank will be the best answer. The pump on your compressor is not adequate. For 200.00 or a little more an adequate compressor is available.

-- .

View JesseTutt's profile


854 posts in 2132 days

#4 posted 02-16-2013 01:49 PM

I saw that article; I think it was in Shop Notes. Yes I have a 5 gallon tank that started its life as a portable tank for inflating tires. I converted it so I can connect it as a reserve (additional) tank for the air compressor or I can take it with me to inflate tires or drive a few nails.

Using it as an additional tank reduces how often the air compressor runs. But, it runs longer when it does run. This might give you another minute or two of spraying at full pressure. I agree with StepheW that the best answer is to buy a “spray gun system that includes it’s own air source.” This is what I did with the Earlex 5000 HVLP system and it has never disappointed me.

-- Jesse, Saint Louis, Missouri

View waho6o9's profile


8204 posts in 2599 days

#5 posted 02-16-2013 01:58 PM

Here’s a review on the Earlex Spray Station 5500


View Moron's profile


5032 posts in 3915 days

#6 posted 02-16-2013 02:05 PM

I’ve seen done, what you ask, many times. You just use your little pancake compressor to fill a larger tank (the bigger the better) and away you go……….works like a charm

-- "Good artists borrow, great artists steal”…..Picasso

View johnstoneb's profile


2932 posts in 2194 days

#7 posted 02-16-2013 02:09 PM

You need a larger compressor. A larger or more tanks will make it longer before the compressor turns on, but it will not increase the capacity of the compressor to produce air under pressure.

-- Bruce, Boise, ID

View David's profile


198 posts in 2685 days

#8 posted 02-16-2013 02:10 PM

10 gallons is about 1.3 cubic feet, so it would only give you a few seconds of extra use on the spray gun before needing to refill. That said, if your compressor puts out 2.6cfm @ 90 psi 4.5cfm at 40psi might be possible. I would check the specs on the compressor output at lower pressures before buying anything else.

I’ve used a 60 year old 1cfm @ 90psi compressor for spraying before, and the spray gun worked fine. My spray gun may not require as much air as yours though.

-- Perilous to all of us are the devices of an art deeper than we ourselves possess. --Gandalf the Grey

View shelly_b's profile


850 posts in 2139 days

#9 posted 02-16-2013 02:29 PM

Thanks guys. I haven’t bought a gun yet, but found one on amazon for under $20 with great reviews. If it doesn’t work, it’s only 20 bucks…

View Stephenw's profile


273 posts in 2407 days

#10 posted 02-16-2013 02:30 PM

David said “That said, if your compressor puts out 2.6cfm @ 90 psi 4.5cfm at 40psi might be possible. I would check the specs on the compressor output at lower pressures before buying anything else.”

I think her compressor puts out 3.5 cfm at 40 psi. It is my experience that the cfm numbers on compressor spec sheets are a little higher than what the compressors can actually produce. The air tools also seem to use more air than the spec sheets claim.

View CharlieM1958's profile


16274 posts in 4240 days

#11 posted 02-16-2013 02:41 PM

I have to agree with those who are saying the extra tank is not going to help much.

The key is what you plan on spraying. For small projects like a box, or an end table, or a single cabinet, your compressor will work just fine. But if you plan on spraying an entire set of kitchen cabinets at one time, you need a bigger compressor or a self-contained HVLP unit.

-- Charlie M. "Woodworking - patience = firewood"

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1970 days

#12 posted 02-16-2013 02:53 PM

what you are referring to is called a “PIG” these are use in industrial settings. it is a 30 gallon tank with a supply line in and feeds out the sides. usually red in color and looks like a momma pig with babies on the side. they are set up when the compressor is to far away.
I have a 30 gallon set up in the front of my shop to run my heavy demand tools, grinders and 3/4” impact, but it is fed by a 60 gal two stage compressor with a 3/4”line. In your situation a 30 would work for spraying but only in short burst. also it would take forever to fill up, and this will severely shorten the life of your compressor because they are designed to cycle, limiting the heat build up on the head. an oil type my last longer, but still wear faster.
your best bet is to go bigger. something like this would serve you just fine

also the HF spray guns work great and can usually be had for $9.99 on sale good luck

View JoeinGa's profile


7736 posts in 2029 days

#13 posted 02-16-2013 03:09 PM

I did exactly what you’re asking … BUT… I had a small (2hp, 30gal) compressor to start with and I had a chance to get a bigger motor and pump (which I jumped on as it was free). Then I needed more VOLUME so I could paint bigger things (like my truck) so I got (again free) another 30gal tank and daisey-chained it to my existing unit.

The thing is, my 5hp motor/pump unit WILL supply the added capacity to my system. Your small pump/motor wont do what you want it to do. Here’s mine before,


And after ..

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View cosmicturner's profile


403 posts in 3417 days

#14 posted 02-16-2013 03:49 PM

I am by no means an expert but dot you just match your spray gun to the output of your compressor? You just can’t spray the same volume…
Nice set up Joe hope that bad boy accumulator is attached real good.

-- Cosmicturner

View Ken90712's profile


17563 posts in 3211 days

#15 posted 02-16-2013 03:59 PM

Funny thing about air compressors, I have a good sized on in my shop as I plumed it for both the garage and woodshop with copper piping. I have a buddy with a machine shop who seems to never run out of air. When I looked at his comp, his tank was smaller than mine which surprised me. When I looked at the motor is was a 5hp much stronger than mine so when it kicked on it filled up the tank quickly & recovered quicker with no noticeable lag. Just food for thought. Good luck.

I have the Earlex 5500 and love that as well.

-- Ken, "Everyday above ground is a good day!"

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