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Old 11-30-2011, 10:01 AM
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What's my CFM rating?

I'm trying to figure out my compressor's cfm rating so I can determine if it'll handle a HVLP gun.
It's a Craftsman 5hp with a thirty gallon horizontal tank, running on 220v.
I've looked all over the thing and it just doesn't mention anything about cfm's.
I've had it about twenty years.
Anybody have a way to fingure it out?

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Old 11-30-2011, 02:42 PM
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the best way I would know how is to rent some air tools and find what it can keep up with. It should be in the 6-10 CFM range, once you found somthing that it cant keep up with, find somthing a little lower till it can keep up with it.
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Old 11-30-2011, 04:48 PM
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MAtt, I already have some air tools but I have no idea what cfm they're rated at. I have straight drills, right angle drills, pancake drills, dotco drills, buckeye drills impact guns, rivet guns, air hammers, screw guns, a DA sander and a die grinder. The little die grinder seems to tax my compressor the most, but I still don't know it's cfm rating. I pilfered it from the shipyard I worked at thirty years ago and any identification on it has long since disappeared.
I may just alter my strategy and buy me one of those new LPLV guns. Either that or splice in another air tank. Just found a 60 gallon tank on Craigslist for 50 bucks.
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Old 11-30-2011, 05:08 PM
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I don't know the answer to your question, but it might help to know, that sounds exactly like same compressor in my shop; and I have used HVLP gun dozens of times without any problem
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Old 12-06-2011, 01:03 AM
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Do they make a tester to check CFM? Found this to help.

1

Determine the volume of your air compressor tank in gallons. This should be clearly marked on the tank itself by the manufacturer.
2

Divide the tank volume by 7.48 (7.48 equals the number of gallons in one cubic foot.) The number that you get after the division is the tank volume expressed in cubic feet.
3

Release the air from your compressor.
4

Begin refilling the compressor with air. Record the amount of time that it takes to refill the tank while paying close attention to the compressor's tank gauge. You will need to record the psig (pounds per square inch) at two separate times in the refill process: once at the moment the compressor kicks in and once at the moment the compressor kicks out.
5

Take the psig indicated on the compressor's tank gauge when the compressor kicked in and subtract it from the psig indicated when the compressor kicked out. For example, if the compressor kicks in at 75 psig and kicks out at 100 psig then the difference would be 25 psig.
6

Divide the difference between the two recorded psigs by 14.7. The result will give you the amount of pressure added during the tank's filling cycle in terms of atm (atmospheric pressure).
7

Take the volume of the tank expressed in cubic feet (calculated in Step 2) and multiply it by the amount of pressure added during the tanks filling cycle in terms of atmospheric pressure (calculated in Step 6). This is the number of cubic feet that your compressor pumps in the time it took for your tank to fill (recorded in Step 4).
8

Convert this number to minutes. To do this, take the number of cubic feet found in Step 7 and divide it by the number of seconds it took to pump this amount. Multiply the result by 60 and you have the CFM of your air compressor.


Read more: How to Calculate the CFM of an Air Compressor | eHow.com http://www.ehow.com/how_5001852_calc...#ixzz1fjfTpEPM

Or

http://www.truetex.com/aircompressors.htm
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Old 12-06-2011, 07:55 AM
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bk , check the hp rating on your compressor. most 5 hp compressors start at a 60 gal tank. my old compressor ( old as me ) was a 3 hp on a 30 gal tank. my 5hp is 60 gal and my 10 hp is on an 80 gal tank. not sure what craftsman does . i know a lot of the newer compressors are 3 hp listed as 6 by using double starters. but the rating on the electric motor will be "sp " whatever that is suppose to be . it takes a lot of maintained pressure at the wall to supply an hvlp .
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Old 12-06-2011, 08:08 AM
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by the way , wish you lived closer so i could steal your hood. mine is a pos. been on fire and beat on something terrible. drivers fender not much better. hard to find parts for a 54 ford pu.
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