Air compressor CFM help!

[nick-flanders]

I'm looking to purchase a new air compressor for my first home. I am limited to 110v and want something that will last, and provide decent CFM so I can occasionally use my small paint guns. The compressor I am leaning towards is an Ingersol Rand 20 gallon unit (http://m.northerntool.com/products/shop~tools~product_200375221_200375221?hotline=false).
Is there any way to convert these CFM ratings down to 40psi since that's the pressure my guns need?

 

[99LeCouch]

That looks to be the same MAT Industries pump and motor as on my Porter Cable 30 gallon. Unless you're set on having an IR compressor in your garage, being open to other brands that use the same motor and pump makes getting a compressor a bit cheaper.

A vertical 30 gallon compressor will provide more run time for your guns than that 20 gallon. It won't give up much in the way of "portability" since these are top-heavy enough where "portable" means it can be wheeled into and out of a corner.

Whatever you do, put aside $50 to convert every quick-connect on the unit, hose, and guns to high-flow. Like Milton V-style or similar. On a smaller compressor, using every bit of air effectively matters more than on a larger one.

 

[nick-flanders]

Fortunately for me my work bought one of these for a project, and the customer upgraded to a larger unit. I can purchase this from my employer for a good price, which is why I'm leaning toward this specifically instead of a 30 ish gallon unit. My plan is to run 1/2 pipe through my garage, and pipe in multiple high flow quick connects. I'm just really curious what effective CFM would be at spraying pressures.

 

[md21722]

It will not be significantly higher, maybe 1 CFM higher.

 

[rlitman]

That's a nice little compressor. We have one at work. It's very quiet compared to an oilless of the same size, though still loud compared to a dental compressor. It is a bit top heavy though, with the motor and cast iron pump up there, so be careful rolling it around.

Anyway, yeah, I would not expect much more CFM at 40 than it delivers at 90.

 

[MoonRise]

A ~5 CFM @ 90 psi compressor is usually about 6 - 6.5 CFM @ 40 psi.

But the real question is what do your spray gun(s) require as far as air flow?

The purple HF HVLP spray gun says it needs ~ 6 CFM @ 40 psi (but another section of the page mentions 8 CFM needed, so YMMV there). But that is the 'average' air demand (sort of like 'peak' HP on an air compressor). The actual air needs for more than a few seconds of use will be ~4x that 'average' air demand, so ~24 CFM @ 40 psi for mostly continuous use.

http://www.harborfreight.com/air-tools/paint/20-oz-8-cfm-gravity-feed-spray-gun-67181.html

Old school non-HVLP quart spray gun from HF says 10 CFM @ 60 psi needed.

http://www.harborfreight.com/air-tools/paint/heavy-duty-air-paint-spray-gun-97855.html

What does your spray gun say it needs?

And what are you trying to spray (material being sprayed and onto what)? Bed liner, epoxy primer, house latex/acrylic paint, solvent based lacquer, shellac, metallic flake paint, what? A car, a house, graffiti, what?

 

[WWheeler]

I'm looking to purchase a new air compressor for my first home. I am limited to 110v and want something that will last, and provide decent CFM so I can occasionally use my small paint guns. The compressor I am leaning towards is an Ingersol Rand 20 gallon unit (http://m.northerntool.com/products/shop~tools~product_200375221_200375221?hotline=false).
Is there any way to convert these CFM ratings down to 40psi since that's the pressure my guns need?

Northern says that model P1.5IU-A9 IR compressor gets 5.5cfm @ 90 psi.

Ingersoll Rand says it gets 5.2cfm @ 90 psi & 4.6cfm @ 135 psi.
http://www.ingersollrandcompressedair.com/P15IU-A9-Single-Stage-Air-Compressor_p_9.html

Just a small difference, but I'd probably trust IR's numbers more than Northern's.

Most other 20 gallon compressors specs add right around ~1 CFM at 40 psi than they show for 90 psi.

 

[nick-flanders]

I use Auto paint with a HVLP gun.. I have a few guns, my Devilbiss GTI will never work with this compressor, but I use my Sharpe Fx1000 a lot for smaller jobs like wheels valve covers, single body panels etc. The sharpe requires 7cfm I believe. I don't plan on painting any full vehicles with this compressor, but peace of mind when it comes to painting a bumper and some wheels.

I have had good luck with Eastwood products in the past. They claim to have a very low CFM LVLP concourse spray gun that may be worth looking into. That claims 4 CFM at 30psi.

It's great to hear this is quiet compared to most other small compressors!