Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis. It is used as a measure of rotational speed of a mechanical component
A measure of the volume of a substance flowing through air within a fixed period of time With regard to indoor air, refers to the amount of air, in cubic feet, that is exchanged with indoor air in a minute's time, i e , the air exchange rate