CFM (Cubic Feet Per Minute)

CFM is one of the two primary specifications used to evaluate a hydrovac truck's vacuum performance, the other being inches of mercury (vacuum depth). CFM measures the volume of air the blower can move per minute and determines how quickly loosened soil and slurry can be transported from the dig point to the debris tank.

Typical CFM ratings for hydrovac trucks range from 2,500 CFM on smaller units to 6,000 CFM or more on large production trucks. Higher CFM does not necessarily mean better performance in all situations. For deep dig and remote dig applications, vacuum depth (inches of mercury) is often more important than airflow volume. For shallow, high-production work, CFM is the dominant performance factor.

It is important to understand that CFM ratings are typically measured at zero vacuum (free air), and actual airflow decreases as vacuum increases. The performance curve showing CFM at various vacuum levels is a more useful specification than the peak CFM number alone. Operators should compare performance curves rather than headline CFM numbers when evaluating different trucks.