Positive displacement blowers, also commonly referred to as PD blowers, circulate air by pulling a specific volume of gas into the rotary chamber before pushing it out. Various processing and manufacturing facilities utilize PD blowers for numerous applications, such as vacuum processing, aeration, air extraction, and cleaning. 

At Energy Machinery, Inc., we’ve been providing quality industrial air compressors, blowers, dryers, pumps, and accessories since 1971. Learn more about the types of PD blowers we offer below.

Buy Positive Displacement Blowers from Energy Machinery

Energy Machinery offers the following types of Gardner DenverTM positive displacement blowers:

Positive Displacement Blower Types

There are two main positive displacement blower types: lobe and screw.

Lobe Blowers

Positive displacement lobe blowers transport a relatively constant volume of gas from the inlet to the discharge port. They function based on the isochoric compression principle (external compression), meaning the medium is forced from an atmospheric state into a system with a set resistance, causing the pressure to increase. As such, lobe blowers are not considered compressors. The configuration of its rotating parts and casing determines the amount of gas the machine can handle. To explore more about efficient airflow solutions, check out our guide on rotary screw air compressors.

Lobe Blowers at a Glance

  • Mechanism: Two or three lobes rotate within the housing to trap air on the inlet side and exhaust it from the outlet.
  • Advantages: Simple design, easy to maintain, reliable, capable of handling high flow rates.
  • Disadvantages: May produce higher noise levels and pulsating airflow.

Screw Blowers

In positive displacement screw blowers, the rotors rotate in opposite directions. When the rotors mesh, they create working chambers between the rotors and casing wall. The gas is pulled in from the intake side and trapped between the rotors, casing, and cover. The gas is then transported to the compression side, where the working chamber shrinks and the gas or air is compressed. Screw blowers provide a steady supply of non-pulsating airflow, resulting in reduced vibration and minimal maintenance requirements. For insights into reducing system vibrations, consider our silent air compressor buying guide.

Screw Blowers at a Glance

  • Mechanism: Intermeshing helical screws compress air as they rotate.
  • Advantages: More efficient than lobe blowers, smoother airflow, quieter operation.
  • Disadvantages: Potentially higher upfront costs, more complex design.

How Does a Positive Displacement Blower Work?

Positive displacement blowers have two rotating impellers inside their central casing. These impellers—which can have two or three lobes—spin in opposite directions to force air into the blower and apply pressure to the air. The air enters the inlet side of the chamber, which is at atmospheric pressure, and traps the air between two rotating impellers inside the machine. The blower then pressurizes and discharges the air to create circulation. The positive displacement process ensures that air cannot return to the chamber and that the airflow is unidirectional.

Positive Displacement Blower vs Centrifugal

Both positive displacement blowers and centrifugal blowers force air movement. Whereas positive displacement blowers use impellers and displacement to force pressurized air through an outlet port, centrifugal blowers use kinetic energy to increase the speed of air moving through the unit. The unit then slows the air through a diffuser to convert the energy into static pressure. Facilities commonly reserve centrifugal blowers for ventilation, continuous gas transfer processes, and aeration applications. Learn more about different types of compressors by visiting our guide on types of air compressors.

Positive Displacement Blowers in Boston and Rockland, MA

PD blowers are responsible for moving air using either rotary lobes or intermeshing helical screws. As a leading provider of superior blowers and compressed air equipment in Boston and Rockland, MA, Energy Machinery can help you determine which blower option is right for your needs. We partner with trusted manufacturers to deliver units and replacement parts to meet your facility’s unique requirements.

For more details about our Gardner DenverTM positive displacement blowers, please contact us or request information today.