What is CFM, SCFM, ACFM, Am³/hr and N m³/hr?

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CFM is a unit of flow rate (cubic feet per minute)

SCFM is a unit of flow rate (Standard Cubic Feet per Minute) at STP condition i.e. standard temperature 60º F and standard pressure 14.69 A PSI.

ACFM (Actual Cubic Feet per Minute) is the actual flow at the operating temperature and pressure conditions.

Am³/hr (Actual Cubic Meter per hour) is the actual flow at the operating temperature and pressure conditions.

Nm³/hr (Normal Cubic Meter per hour) is normalized value of flow at NTP conditions i.e. flow at Normal Temperature 0º C and Normal Pressure 101.32 kPa condition.

Note : STP/NTP conditions are decided by different organizations/authorities as per their specifications.

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CFM

CFM stands for “cubic feet per minute.” It is a unit of measurement used to quantify the volume flow rate of a gas or air in cubic feet per minute. It is commonly used in HVAC (heating, ventilation, and air conditioning) systems to measure the airflow.

SCFM

SCFM stands for “standard cubic feet per minute.” It is similar to CFM but takes into account the standard conditions of temperature and pressure. SCFM measurements are adjusted to a standard set of reference conditions, typically 68 degrees Fahrenheit (20 degrees Celsius) and 14.7 pounds per square inch absolute (psia) or atmospheric pressure.

ACFM

ACFM stands for “actual cubic feet per minute.” It represents the actual volume flow rate of a gas or air at the existing temperature and pressure conditions. ACFM measurements are not adjusted to standard conditions and reflect the real-time flow rate.

Am³/hr

Am³/hr stands for “actual cubic meters per hour.” It is a metric unit of measurement used to express the actual volume flow rate of a gas or air in cubic meters per hour. Similar to ACFM, it represents the flow rate at the existing temperature and pressure conditions.

N m³/hr

N m³/hr stands for “normal cubic meters per hour.” It is a metric unit of measurement used to indicate the flow rate of a gas or air at standard reference conditions. The standard reference conditions for N m³/hr are typically defined as 0 degrees Celsius (32 degrees Fahrenheit) and 1 atmosphere of pressure (101.325 kilopascals or 14.7 pounds per square inch absolute).

Both ACFM and Am³/hr represent the actual flow rate at the existing conditions, while SCFM and N m³/hr take into account standard or reference conditions for comparison and normalization purposes. It’s important to be aware of the specific conditions under which flow rates are measured and specified to ensure accurate and consistent measurements.