CFM and Compressor CFM output puzzles me

by Ron
(England)

CFM and Compressor CFM output puzzles me?


Ok , so I am really confused here. I have an 11 kw compressor that?s produces roughly 60 cfm at 7 bar.

Now if I look at the CFM usage charts for some air tools even the guide chart on this site, take an air drill for example 60-80 cfm.

Huh so if I run this drill for 1 minute an 11kw compressor can just about keep it going?
I am clearly missing plot here?
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Ron, no, I don't think you are missing anything.

Let me put it this way. Let us assume that your car needs 1 litre of gasoline per minute to run properly. Less than that flow of gasoline will not allow your motor to run properly, and if your fuel flow is less than that, the motor will likely stall.

You bought a gas pump to supply fuel to this same car. The gas pump you bought can pump .5 litres per minute.

The car doesn't care if the gas pump has enough capacity. All it "knows" is that it is not getting enough gas, and in stalls.

Your air tool doesn't care if your air compressor doesn't have enough flow. It just won't work properly if you "under fuel" it with a too small air compressor.

Check each air tool specs. If it says that the tool needs, for example, 15 CFM of compressed air at 6 bar to run properly, you either give it that flow, or the air tool won't work as expected.

You say your compressor can "produces roughly 60 cfm at 7 bar." That means that you can run an air tool that demands less or the same amount of air as that continuously, if the compressor is 100% duty cycle. See the DUTY CYCLE page for more details on this term if needed.

The guidelines provided are just that. They are intended to make folks realize that some air tools are have huge demands for compressed air flow, and to help the understanding that you cannot expect to run a high-demand air tool on a too small air compressor.

If you need to power any air tool with compressed air, you need to know what the air demand for that air tool is to know if your air compressor can fuel it.

Cheers,

Bill


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Use a 1/4" die grinder with Makita MAC5200?

I am trying to use a 1/4" die grinder with my Makita MAC5200.

The compressor is rated at 6.5 cfm @ 90 psi

The grinder starts out fast but quickly slows down to a stop.
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If you don't have an impediment in the air line from the compressor to the air tool, then I suspect that your air compressor is undersized for the air demand of the air tool.

Somewhere on the tool, or in the literature that came with it, it should say what the minimum flow and operating pressure for your die grinder air tool is.

Compare those figures to the output of your air compressor.

You will see, I expect, that the demands of the die grinder exceed the discharge capacity of your compressor, and when you start grinding with a full tank of air, your grinder will work OK for a few seconds / minutes, and then starve for air.

Cheers,

Bill

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Tools to use with my compressor?

by Nat Pascuzzo
(Montreal,Canada)

I have the hitachi ec510 1.1 hp 2.0 cfm @ 90 psi 6 gallon tank.what tools can i use with this compressor?

thankyou
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Nat, to point out the obvious, you can use any air tool that has an air demand of 2 CFM or less at 90 PSI.

You need to size the tool (read the tool air flow and pressure demand specifications before you buy the tool) to your compressor capacity, or you will be disappointed with the results.

You have a very small air compressor, so don't even think about high demand air tools like grinders, sanders, air ratchets etc. These will run for only a few seconds before being starved for air.

If your air compressor is not 100% duty cycle, and if you opt to try and run a high demand air tool, odds are good you'll fry your compressor too.

Not happy news, but your air compressor is a pretty small one, good for nailers, staplers, air tools that use a single shot of air per cycle as opposed to a high flow of air to run vanes inside a tool.

Cheers,

Bill

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CFM's air compressors - rock carving tools

by Michele
(Salt Lake City, Utah)

I'm carving in quarts flag stone rock. I've been told I need at least 25 to 45 CFM Air Compressor. Can I do it with less CFM?
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Michele, that's the wrong way around type of question.

Look to your rock carving tools. Read the manual that came with them or look for a tag on the tool itself that will tell what that air tool's demand in CFM and PSI.

If you don't give the air tool what it needs in pressure and flow, it won't run properly.

I wouldn't buy a compressor without knowing what my air tools needed in flow and pressure. You can err on the side of caution and buy a big air compressor, but that is expensive, and may not be necessary.

Can you work your tools with less CFM? Sure, as long as the compressed air supply reaches the minimum that the air tool needs. And to figure that out, you need to find out your air tool compressed air needs.

Cheers,

Bill

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