SCFM (Standard CFM) and ACFM (Actual CFM) are commonly used units for measuring gas flow rate. For example, in the air compressor industry, they are used to measure airflow and air consumption. So what are the differences between them? How should they be converted?
Both SCFM and ACFM are based on CFM. CFM is a commonly used unit for gas flow rate, representing the number of cubic feet passing through per minute. It is mainly used to measure the volumetric flow rate of gas passing through per unit time.
In the International System of Units (SI), we usually use cubic meters per hour (m³/h) to express gas flow rate, while in the Imperial System, CFM is the commonly used representation. Specifically, 1 CFM equals 28.316846592 liters per minute (L/min), or 0.028316847 cubic meters per minute (m³/min).
However, CFM is affected by parameters such as altitude, temperature, and elevation, leading to the development of SCFM, ACFM, and IFCM.
What is SCFM?
SCFM, or standard cubic feet per minute, is the flow rate of a compressor under standard conditions. This is a very common measurement method when comparing compressors, allowing for “same-class” evaluations. Keep in mind that standard conditions are difficult to meet in real life, but it is still a more practical measurement method because it allows for fair comparisons between compressors.
SCFM is widely used in industrial, chemical, and engineering fields to measure gas flow rate.
What is ACFM?
However, in actual measurements, the temperature, pressure, and other parameters are not exactly the same as in standard operating conditions. Therefore, the actual gas flow unit, ACFM, was developed.
ACFM is actual cubic feet per minute. This means it describes the actual flow rate considering environmental conditions. While this measurement may more accurately describe the actual gas flow rate, it is illogical to specify a compressor/gas flow meter based on ACFM due to the extremely wide range of possible environmental conditions.
Therefore, most of the time, when purchasing a compressor or gas flow meter, we need to convert the ACFM under actual operating conditions to SCFM under standard operating conditions. You can also use our online calculator.
Online Calculator
Professional tools for ACFM, SCFM, and m³/h calculations.
(Standardized to 14.7 PSIA & 60°F)
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