There are many factors one must look out for when using measurement units. There are two types of measurement units; one the SI units, and the other is the non-SI units.
Key Takeaways
- CFM (Cubic Feet per Minute) is a unit of measurement for airflow, indicating the volume of air that flows through a system in one minute at standard conditions.
- SCFM (Standard Cubic Feet per Minute) is also a unit of measurement for airflow. Still, it considers varying temperature, pressure, and humidity levels, standardizing these factors to provide a more accurate comparison between different systems.
- The primary distinction between CFM and SCFM is that CFM measures airflow without accounting for temperature, pressure, and humidity changes. At the same time, SCFM standardizes these factors to provide a more consistent measurement across different conditions and systems.
CFM vs. SCFM
The difference between CFM and SCFM is that CFM has no standard pressure, volume, or temperature in which the volume flow of gas is to be calculated. In contrast, SCFM has a standard volume, pressure, and temperature in which the gas volume flow rate is measured.
Although the standards can vary from place to place, having a standardized and controlled environment to measure a massโs flow rate is more efficient and easy than measuring the same rate of flow of a mass in a non-standardized situation.
Many people use these terms interchangeably, but when you want to measure the rate of flow of a gas or any other mass in an industry, it is preferable to use the standard cubic feet per minute measurement instead of the CFM.
Comparison Table
| Parameters of Comparison | CFM | SCFM |
|---|---|---|
| Full form | The full form of CFM is Cubic Feet per Minute. | The full form of SCFM is Standard Cubic Feet per Minute. |
| Standardization | There is no standard condition at which the CFM values should be calculated. | There is a standard volume, pressure, and temperature at which the SCFM values must be calculated. |
| Measurement | CFM is a smaller number than SCFM as it is calculated at higher pressure, making the air volume small. | SCFM is always a bigger number than the CFM as it is calculated at lower pressure, making the air volume larger. |
| Calculation | To calculate CFM values, the pressure is maintained under 90psi. | To calculate SCFM values, the air or gas is expanded to a standard condition of around 14.7psi. |
| Indication | CFM is more relevant to the internal capacity of an air compressor. | SCFM indicates how the gas pressurized to a standard value will perform at the end-point applications. |
What is CFM?
CFM stands for Cubic Feet per Minute. The term itself is very confusing as it does not have a single definition that applies to all situations.
CFM describes the volume of air that occurs at an exact pressure or temperature. Compared to SCFM, CFM values are always a smaller number as they are calculated at a higher pressure, decreasing the volume of gas and making it smaller.
To measure CFM, the pressure is taken to under 90psi. It is more related to the internal capacity of an air compressor. There is no standard temperature or volume at which it is calculated.
What is SCFM?
SCFM stands for Standard Cubic Feet per Minute. The molar flow rate of a gas is subjected to standardized conditions of fixed pressure and temperature.
There are many standard conditions for pressure, temperature, and even relative humidity, so care must be taken while choosing a standard condition.
As the pressure is low, the volume of gas is bigger, and thus, SCFM is always a greater number than CFM. Although the standard values can differ from place to place, it is still preferable to use the SCFM measurement unit than the CFM.
Main Differences Between CFM and SCFM
- CFM values are taken under the pressure of 90psi, whereas to calculate scfm, the air is expanded to a standard condition of around 14.7 psi.
- CFM is more relevant to the internal capacity of an air compressor. At the same time, SCFM indicates how the gas pressurized to a standard value will perform at the endpoint applications.
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
