When you want to try buying an air compressor, you can see the same unique metric in the body of an air compressor. These are pressure (PSI), CFM, Horsepower, SCFM, tank capacity and many more. But when you buy an air compressor the first time, you see the CFM on the body or company try to marketing with the CFM.
Table of Contents
What is Air Compressor CFM?
CFM is the acronym of cubic feet per minute which is the measurement of the mass of air flowing to push out from the compressor. But one you have to know, CFM does not mean the compressed volume of air, It means the mass air flowing per minute. That means CFM measure the mass, not the volume.
When you see the CFM on the body, some company talked about the SCFM, ACFM, and NCFM. What is the difference between the name of CFM, SCFM, ACFM, and NCFM? SCFM is the acronym of standard cubic feet per minute which is the measurement of the mass of air flow with specific pressure and temperature.
So what is the difference between CFM and SCFM? SCFM measure with the specific pressure and temperature. Right! But CFM is not measured with the specific pressure and temperature. Then what is ACFM? Actual Cubic Feet per Minute (ACFM) is a unit of volumetric flow of actual gas in inlet conditions. So what is the difference between CFM and ACFM? The different is actual and not actual. Right! Normal cubic feet per minute (NCFM) is mass of air flow in nor conditions such as 14.7 psia, 68℉, and 36% relative humidity.
How CFM is calculated in air compressor?
Why we think about the calculation of CFM. Every company gives their specification with the CFM. But in every company’s CFM is not accurate. So we discuss how to calculate the CFM of an air compressor? You don’t need to the laboratory for testing the CFM.
Air Compressor CFM Calculation Formula
CFM= Tank volume in cubic feet * ATM of pressure during cycle* Crank time in the minute
We discuss with an example and it might be clear. Example- An air compressor bears a sticker where they claim the air compressor has 4 Horsepower (HP), tank capacity 30 gallons, 14 CFM at 90 psi. We can calculate the CFM. Let’s see.
At first, we convert the tank capacity gallons to cubic feet. We know 1 cubic foot is equal to 7.48 gallons. We calculate 30/ 7.48 = 4.01 cubic feet.
Now you should start the compressor and we measure the time of cuts in and cuts out on the tank gauge. We test and get cuts in 90 psi and cuts out 110 psi. The difference between cuts in and cuts out is 20 psi and get the crank time 37 seconds. You need a stopwatch or a mobile and a pen and paper. We know 1 atm= 14.7 psi. Now we can convert in atm of pressure during the cycle (20/14.7= 1.36 atm of pressure during the cycle).
Now we convert the time 37 seconds to minutes like 37/60 is equal to 0.6166 minutes.
So we get three units-
- Tank volume in cubic feet = 4.01
- ATM of pressure during the cycle = 1.36
- Crank time in minute = 0.6166 minutes
Our formula is-
CFM = Tank volume in cubic feet * ATM of pressure during cycle* Crank time in the minute
CFM So it occurs an error to CFM and you can understand the procedure. You can calculate the CFM at home for your air compressor.
What CFM compressor do I need?
This is the most important question for every new potential buyer. What CFM do you need? You can check the CFM chart of tools. You can decide what CFM you need. You can easily dterment the CFM of your tools.
Air Compressor CFM Chart
|Name of the Tools||Pressure In PSI||CFM||Name of the Tools||Pressure In PSI||CFM|
|SPRAY GUNS||6" Medium Duty Sander||70-100||40|
|Engine Cleaner||90-100||5||Air Filter Cleaner||70-100||3|
|Production Paint Spray Gun||90-100||8||Body Polisher||70-100||20|
|Touch up paint Spray Gun||90-100||4||Body Sander (Orbital)||70-100||20|
|Undercoat Paint Spray Gun||90-100||19||Brake Tester||70-100||20|
|TIRE TOOLS||Carbon Remover||70-100||20|
|Rim Stripper||125-150||6||Panel Cutter||70-100||20|
|Tire Changer||125-150||1||Drill, 1/16" to 3/8"||70-90||20|
|Tire Inflation Line||125-150||2||Impact Wrench 3/8" sq dr||70-90||20|
|Tire Spreader||125-150||1||Impact Wrench 1/2" sq dr||70-90||20|
|Vacuum Cleaner||125-150||7||Impact Wrench 5/8" sq dr||70-90||20|
|HAMMERS||Impact Wrench 3/4" sq dr||70-90||20|
|Air Hammer||90-100||4||Impact Wrench 1" sq dr||70-90||20|
|Bead Breaker||125-150||12||Die Grinder||70-90||20|
|Spring Oiler||90-100||4||Vertical Disc Sanders||90-100||20|
|Tire Hammer||90-100||12||Filing and Sawing Machine, Small||90-100||20|
|OTHER EQUIPMENT||Filing and Sawing Machine, Lar||90-100||20|
|Grease Gun||120-150||3||Burring Tool||90-100||20|
|Car Lift||145-175||6||Dusting Gun (blow gun)||90-100||20|
|Floor Jacks||125-150||6||Car Washer||70-100||9|
|Pneumatic Garage Door||120-150||3||Fender Hammer||70-100||9|
|Radiator Tester||90-100||1||Transmission Flusher||70-100||3|
|Spark Plug Cleaner||90-100||5||Spark Plug Tester||90-100||0.5|
PSI to SCFM Calculator
PSI and SCFM are not converted to each other. Because it is the nontangible term. PSI means pound-force per square inch and SCFM means standard cubic feet per minute. These terms are not equivalent to each other but both are shown the compressor performance.
Now you can calculate the CFM of your air compressor. If you want to buy an air compressor for a newbie, you read the article “Best Air Compressor“. If you have any question, comments below without hesitations.