Glossary

Positive Displacement (PD) Blower

What is Positive Displacement (PD) Blower?

A positive displacement (PD) blower is a high-vacuum air pump used on vacuum and hydrovac trucks that produces strong lift for deep digging and long hose runs, moving air by trapping and displacing fixed volumes.

A positive displacement blower generates vacuum by trapping air in cavities between rotating lobes and forcing it out, delivering high vacuum lift (measured in inches of mercury) even through long or vertical hoses. This makes PD blowers well suited to deep potholing, remote spoil removal, and heavy material.

PD blowers contrast with fan blowers, which move more air (higher CFM) at lower lift and excel at shallow, high-volume work. Choosing between them depends on dig depth, hose length, and material. Vac4Rent listings note blower type and CFM; submit a free request to match the right blower to your job.