# What size air compressor do I need?



## Illinoiswoodworker (Mar 24, 2013)

My current air compressor is too small I fear. It is Craftsman 25 gal. 5.5 SCFM.
I will probably go 220V but how big? I want to spend $750, or less if I can. 
I'm tired of hearing it run every time I use the air nozzle anyway.

Where are some good places to look and what brands should I look for and which should I avoid?


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## devann (Jan 11, 2011)

Size is hard to tell without knowing what you want to do with it.
I'm kinda partial to Rol-Air,Jacuzzi,Ingersoll Rand, & Emglo. I have worn out quite a few. I've gotten away from cast iron heads on the pump as they run hotter and tend to boil the oil. After breakin use I use Amsoil synthetic oil.
My larger compressor these days is a custom built (from a compressor shop) that uses an Ingersoll Rand pump with a Baldor electric motor on a Gunslinger set of tanks. I've worn out one pump on it so far, motor is still going. The unit is pushing twenty years old but honestly it doesn't see much use these days. 
My smaller, pick up with one hand compressor is a cheap no name brand that I purchase at a auto parts store for less that $100. It does have a Jacuzzi pump. I've been using it a lot for several years now.

Be aware of the dry tank/wet tank situation on multi tank air compressors. I remember a fellow working for me years ago that showed up with a little Hitachi and it was plumbed backwards. The pump was piped to the top tank and and female air fitting came off the lower tank. Water runs down hill. To Hitachi's credit they since reversed the plumbing.


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## cutworm (Oct 2, 2010)

Man. I have a 1.5hp 10 gallon. It seems to do ok but I only spray finish smaller jobs. But when I do upgrade it would be Rol Air or Ingersall like Darrell mentioned.


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## AandCstyle (Mar 21, 2012)

I have a 3HP 60 gal IR and it seems to be a fine machine for my needs. I mostly only use it for spray finishing. Unless I am spraying a big panel, like 3'x5', it keeps up just fine. I have not had any issues with it in the 5 years I've had it.


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## indianajoe (Dec 20, 2012)

for whatever its worth I personally like oil lubricated air compressors. I understand some people say the oil gets into air lines but with a good separator and a well maintained compressor you wont have that. I think oil free compressors are very loud and don't last very long. The best possible set up is a screw type compressor. You cant even hear them run but for your budget and most peoples that isn't an option.


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## woodbutcherbynight (Oct 21, 2011)

Several good comments above. You did not say what you were using it for so hard to guess what would work best for you. But you did comment about the noise and this fix is easy but so few use it. Make a lean to outside your shop, plumb a main line through the wall using steel pipe and run a few nipples to spaces you use the most. Now the noise is outside let the birds and other wildlife enjoy it, and you have one less larger tool in the shop. I have had this for 20+ years and use a 6HP 220vt 80 gallon tank. Never had an issue and it stays "ON" all the time except for maint every 3 months and to drain the tank.


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## Kobra (Mar 13, 2013)

I have the Puma. I was at Northern Tool and compared it with IR's version. The only difference I could tell was the paint color. It does everything I need it to do.

I agree with indianjoe. My sister's boyfriend has a Craftsman 25 gal oil less and I could not believe how loud that thing was. Oil lubricated air compressors are the way to go.


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## lumberjoe (Mar 30, 2012)

I love my IR and would recommend it to anyone. In fact I am selling it! It's just TOO big for what I need it to do now. When I was doing automotive stuff it was great. Now that I spray finish and use brad nailers, a 20 gallon is plenty.


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## redryder (Nov 28, 2009)

I agree with "woodbut" above. Build a dog house outside, insulate it and pocket most of that $750. Or use the rest to buy more tools. I moved mine to another room and can barely hear it running…..............


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## BUBBATAY (Jan 24, 2012)

If you have a tractor supply in your area they have an upright ingersoll rand 3 hp 60 gallon for $599.


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## Illinoiswoodworker (Mar 24, 2013)

I'm sorry for being unclear in my first post.

I am spraying finishes on woodworking. My current spray gun is a DeVilbiss, model #GFC - 616 - 43FW.
I emailed Devilbiss, they said that it requires 15 CFM to operate???! Is that correct?

I am looking, and it looks like I will have to cough up about a $1000 for a bottom of the line air compressor that will produce >15 CFM.

I am contemplating selling my paint gun, which is brand new, never have been out of the box and buy a gun with less CFM and a smaller air compressor.

I might be a couple hunded dollars ahead that way.

Yes, I was thinking of moving the air compressor to another part of my building, which is not heated. My question is if I am spraying in my heated shop at 65 degrees and the air is coming from a 20 degrees F. Will I have condensation issues and finish problems when I spray?


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## BUBBATAY (Jan 24, 2012)

Compressor cfm rating are usually listed at different pressures i.e. 12 cfm

```
40 psi.  , 15 cfm
```
 10 psi. a hvlp spray gun would only require at most 40 psi which a 3 hp compressor would be sufficient.


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## pintodeluxe (Sep 12, 2010)

I have been happy with my mid-sized Speed Aire. I have had it 23 years with no more maintenance than a few oil changes. 
It will run everything but a sand blaster.


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## pjones46 (Mar 1, 2011)

Convert to an HVLP top feed gun for use with a conventional air compressor, some work well to as low as 3.5 CFM but many range from 4 to 5 CFM and working pressure is around 20-40 psi. You run your compressor at about 100 PSI but put an inexpensive inline regulator off of that. Keep your old compressor and save your money. Woodcraft has a faily inexpensive one, think it is a woodriver.


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## Illinoiswoodworker (Mar 24, 2013)

My Step dad gave me his old Craftsman 29 gal 5hp 9 CFM at 40 psi. I have an identical compressor. If I gang them together that will give me approximately 18CFM. I will go to ACE tomorrow after work and get the plumbing to link them together. I will try it out this weekend and let you guys know how it works.

If this isn't enough, Ill buy a 60 gal 3 or 5 HP.


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## JarodMorris (Nov 24, 2011)

If 2 compressors putting out a total of 18 CFM @ 40 psi isn't enough, then I'd really like to know what it is that you're doing.


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## Illinoiswoodworker (Mar 24, 2013)

JM, 9CFM is with just my air compressor. I have a 9 CFM air compressor that my step-dad gave me that he had some problems with. He said that it pulled down on him while he was using it. He thought it might be seizing up? It has been sitting inside my shed for a few years and I forgot about it until recently. I drug it out and plugged it in and it worked. 
That is how I arrived at 18 CFM.

As long as it doesn't crap out on me, I'll be fine.


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## Captmike001 (Mar 21, 2016)

Regarding compressor noise, my buddy built a storage closet in his garage for the compressor. 
He insulated it and then I helped him to wire in a 110 outlet for some added versatility.
It keeps the compressor noise at a minimum + he keeps a small bar fridge in there for his Mtn Dew, and his beer.


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## Woodbum (Jan 3, 2010)

Look at California Air tools (CAT). Decent pricing, quiet and great customer service. JMHO.


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## jimintx (Jan 23, 2014)

I am really impressed with the California Air Tools machines. I don't know if they have screw pumps, but whatever their design is - they are unbelievably quiet. I'd like to know what the design elements are that lead to such low noise.

As to a question above about comprising cold air, it should be plenty hot after it has been compressed, regardless of the air temp from which it is pulling.
'


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## OSU55 (Dec 14, 2012)

You need cfm

```
psi ratings for the gun and compressor. My gun is spec'd at 11cfm
```
 29psi (32.7 scfm) at the gun (CA Technology CPR-G). My compressor is rated 5.3 cfm @ 90 psi (37.7 scfm), 33 gal tank. The compressor is probably rated a little high. It works fine except when spraying a large piece, dining room table, large bookcase - I do have to wait a few minutes at time to let the compressor catch up. It depends some on what I'm spraying - lower viscosity stuff like shellac don't take as much gun pressure, and are never an issue. I have another similar sized compressor I temporarily pipe in (connect to a bulk head fitting in the tank of the main compressor) when needed, which is seldom, but that depends on project size.

Calculate scfm compressor example: (90psi + 14.7) / 14.7 * 5.3 cfm = 37.7 scfm
Compression ratio x cfm

Be aware that you really need different combinations of tips/fluid nozzles for different viscosity fluids to get correct atomization. Research viscosity cups - there are expensive ones and cheap ones. The cheap ones will do. Allows you to match the fluid to the nozzle/tip. If you are always going to spray the same thing, Devilbiss can tell you the best tip/nozzle combination.


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## dhazelton (Feb 11, 2012)

I'd get an electric HVLP setup. Unless you have a lot of other air tools or plan on sand blasting or painting cars I don't see the point of a huge compressor.


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## bigblockyeti (Sep 9, 2013)

I have three compressors, a Senco hotdog tank that's great for portability and recovers pretty quickly for a small compressor. A 26 gallon belt drive Porter Cable (made by Devilbiss) that stays in the garage and does great for most mechanic work including long stints running die grinders, blow guns & DA sanders. It's still a little noisy as the compressor pump is aluminium with iron cylinder sleeves but still quieter than the little Senco. The big compressor is an 80 gallon, pressure lubed Quincy with a 7.5hp motor. It is very quiet a with most of the noise coming from the intake silencer/filter and the air output is significant at ~ 30cfm but it pulls just under 40 amps (240VAC) at full load and takes up a lot of floor space. All three are oil lubed

The best thing you can put on your compressor is a good water separator to keep moisture and whatever else might be coming from your pump and tank from making it's way into your finish. A good regulator is also a nice addition vs. the cheap ones most compressors come with.

If you're going to put your compressor in an environment different than that where you'll be spraying it would be beneficial to add a decent sized surge tank within the same environment where spraying will take place and put a water separator right after both tanks and your regulator after the second separator.
This would give you clean, dry air and a bit more capacity in the event you're use air a little faster than your compressor can produce it, you'll have longer before having to stop to let it catch up.


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## tomsteve (Jan 23, 2015)

imo, people can either overthink or underthink cfm's and guns.
I bought a copper tekna for auto body work. people screamed I needed an 80 gallon two stage compressor.
except for one- my sons step dad who had worked autobody( not stealership autobody-restoration work) his entire life. he said id be good with a 60 gallon single stage 5 hp compressor- its all a matter of if I have the trigger pulled long enough so the compressor kick in and cant keep up. if the compressor dropped below 90psi, I MIGHT see trouble at the gun. 
I have sprayed about 20 cars and trucks and never encountered a problem spraying vehicles.
the only way I could equal having the triggered pulled as much as on painting a vehicle is if I had a 20 or so foot long floor to ceiling floor unit.
ive built a lot of furniture and built ins with many different finishes. my copper tekna with 1.3 tip and 60 gallon, single stage 5hp compressor has done it all and done it great.

that's a good gun ya have there and should give ya some excellent finishes.
do you happen to have a filter for your compressor and regulator at the gun?


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## jimintx (Jan 23, 2014)

> I am really impressed with the California Air Tools machines. I don t know if they have screw pumps, but whatever their design is - they are unbelievably quiet. I d like to know what the design elements are that lead to such low noise.
> 
> - jimintx


I have gotten around to answering my own question:
The CAT site shows their machines are oil free, and have piston style pumps.

The one I have been focusing on is a 110volt machine, the 10020C Ultra Quiet
2.0 HP (Rated/Running), 10 Gallon vertical steel tank
6.40 CFM

```
40 PSI      <br />5.30 CFM
```
 90 PSI

That is plenty of air flow for me, although I do not use it for any paint or finish spraying. I need to keep cost under control, and I specially like the air ratings of this one for its footprint, since i also place a high value on space in the shop. Being super quiet is a very nice feature.


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