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If you’ve recently been tinkering with an air compressor, you might have encountered new terminologies. The commonly used ones are SCFM and CFM which are ratings. You’re probably wondering is SCFM higher than CFM and how people came up with the rating.
Is SCFM Higher Than CFM?
SCFM is a higher rating compared to CFM. This is because CFM rating comes after the air is pressurized around 90 PSI which results to smaller air volume. Whereas SCFM have a more standardized rating and used by most air compressors.
Most air compressor makers use a standard condition for expanding air while also taking specific variables into account. This standard condition has a lower pressure of 14..7 PSI compared to CFM’s 90 PSI. This makes the volume bigger and that’s why SCFM is higher than CFM.
What Is SCFM?
SCFM is a unit of measurement related to rating air compressors. It is the basis for getting an air compressor to what is most compatible with your needed applications. SCFM is considered the standard for most air compressor manufacturers.
SCFM stands for standard cubic feet per minute. It’s related to how much air can an air compressor process. The SCFM rating helps you determine what tools you can use with your air compressor.
The bigger and more powerful the air compressor, the higher the SCFM rating usually is. This is something you should keep in mind when buying an air compressor.
What Is CFM?
CFM is also a unit of measurement of the volume of discharged air from a compressor over time. Its units are derived from volume and time and it stands for cubic feet per minute. Compressors generally have a specific number of CFM from their discharge point.
People often get confused between the two when they first use air compressors. While SCFM may look more important, CFM is also an essential measurement for understanding how to improve or make full use of your air compressor.
Difference Between the Two
While both may sound the same, they are actually quite different. SCFM refers to how the pressurized air into standard value perform when used on to the air tool from the compressor. CFM on the other hand, is more closely related to the internal capacity of the air compressor.
SCFM is measured through a standard condition where the atmospheric pressure is 14.7 PSI, temperature is 68 degrees Fahrenheit, and a 36% relative humidity. CFM in air compressors are measured through different standards and may follow real-world setting.
Hence, CFM measures the “actual flow rate” of the air compressor and is generally used for measuring airflow rate in the United States. You can find the CFM value by doing this test:
- First, find the volume of the air compressor tank. It’s usually in gallons and air compressor manufacturers have it specified on the product.
- Divide the value by 7.48 to get your tank volume.
- Empty the air from your air compressor.
- Refill the air compressor with air. Record the amount of time for it to refill the tank and monitor the tank gauge.
- Record the PSI the moment the air compressor kicks in and when it kicks out. You have to label them like PSI initial and PSI final.
- Subtract PSI initial from PSI final and divide the result by 14.7. The result you get is the pressure in the compressor tank during the refill.
- Divide the tank volume from earlier and multiply it with the pressure of the compressor tank during the refill.
- Now, convert the result to minutes by dividing it by the number of seconds for the compressor to pump the amount of air.
- Multiply the result by 60 and you get your air compressor CFM.
Other Air Compressor Ratings to Check
It’s not only SCFM and CFM that you should know about. Other ratings also matter and they also relate to SCFM and CFM.
- PSI – also known as pounds per square inch. It refers to the amount of pressure forced through the compressor per square inch of area. PSI is a good measurement for determining the effectiveness of air compressors in things such as using air compressors for spray painting projects, installing roof materials with air compressors, and inflating car tires with air compressors.
- Duty Cycle – you may read the on/off cycle. When the compressor is on off cycle, it is not technically tuned off. However, it’s also not in used for pressurizing air. It is expressed by percentage. For example, if the air compressor has a duty cycle of 70/30 then it works 70% of the time and idles for 30% of the time.
- Horsepower – measures the efficiency of the motor of an air compressor at a given CFM and PSI. it is an important indicator for how good the compressor would be for certain applications, like when you use air compressors to fill a tire.
- Gallons – refers to the tank capacity of the air compressor. Generally, the larger the gallon size, the longer the compressor works, compared to a 3-gallon air compressor that can only be used for light applications.
Are Compressors Rated in CFM or SCFM?
Compressors have both ratings of CFM and SCFM. generally, manufacturers provide them for you. There’s also a way you can rate it for yourself.
Is Higher SCFM Better?
Not necessarily because it depends on the application. What you should know is that higher SCFM provides more air and are more efficient for larger applications.
SCFM and CFM are both important ratings for air compressors. While they are closely similar, they also have significant differences. In the end, you need to consider both when you are choosing an air compressor for the application you gonna work on.