CFM vs SCFM

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Old 10-28-08, 08:07 PM
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CFM vs SCFM

I wasn't sure where to ask this question, but it has to do with paint spray guns and an appropriate air compressor. I wasn't sure if the two units (CFM / SCFM) are equal or diff.

I just wanted to know if a spray gun that consumes 3 CFM @ 50 PSI will work with an air compressor rated at 2.4 SCFM @ 90 PSI?

(The gun is a 4 oz detail sprayer that I got as a present and the compressor is that $99 dollar 3 gallon Craftsman always on sale at Sears.) Thanks in advance.
 
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Old 10-29-08, 04:07 AM
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CFM = cubic feet per minute [how much air it comsumes] I'm not sure what SCFM is

Generally when painting with compressed air, the bigger the tank [and motor/pump] the better. Since your detail gun has a low cfm requirement, it should work ok. If you see the compressor struggling to keep up, you will need to stop and wait on it to build the pressure back up.

For most cup guns a small compressor like yours would be woefully inadequate but it may work ok with your little gun. You might as well try it and see.... post back how it works for you.
 
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Old 10-29-08, 06:20 AM
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Standard Cubic Feet per Minute

Not sure what the diff is either..maybe something to do with temps?
Don't think it would make much diff.

Ahhhh yep here....http://encyclopedia.thefreedictionary.com/SCFM
 
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Old 10-29-08, 01:39 PM
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Technically your gun will indeed spew paint with any compressor with a tank that can provide the pressure.

Whether or not your compressor can keep up for a sustained time with the load a a different pressure is a question that can only be answered by a full compressor spec sheet.

I'd keep an eye on the tank pressure gauge, and pause your painting if it gets too near your output pressure.

Also, I hope you don't want to paint something large with that thing. A $99 compressor isn't made for a very constant duty cycle. If the motor is constantly running, it will not be long for this world.

SirWired
 
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Old 10-29-08, 10:16 PM
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Thanks for the replies. Posted previously in the 'Furniture and Cabinetry..' section, the plan was to spray a few coats of tinted poly or varnish to darken the stain on a small end table top. I was hoping to get a mirror deep finish without the worry of brush marks. I'm hoping to get start the small project this weekend.

I take it that the mention of 'spewing paint' from this gun is a bad thing
 
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Old 10-30-08, 03:43 AM
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The paint/poly has to atomize to come out of the the spray tip to properly come out in the spray fan form. The thinner the coating, the less it takes to atomize but you still need the proper amount of air flow. When the air flow becomes to low, paint will still come out but it will spit/drip instead of spray.

With a little practice, you'll be able to tell when the spray fan is changing - that's when you need to stop and let the air compressor catch up.
 
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