Pd blower or rotary air blower, is a type of machine that is used to move gas or air for a variety of applications. More specifically, these devices utilize positive displacement technology by trapping a certain volume of air then discharging or forcing it out against the system pressure. This air is usually forced into some type of pipe or hose to propel materials or gas to a destination. 1. Twin lobe blowers 2. Tri lobe blowers 3.regenerative blowers