Guide: Select and Size the Right Industrial Blower for your Applications

Rev. February 25, 2022   Orig. April 17, 2020

Understanding how to size and select an industrial blower benefits both productivity and the bottom line. The Carotek/Gardner Denver Industrial Blower Selection Guide makes it easier to contribute to the PD blower selection and sizing process.

Positive displacement blowers

How a Positive Displacement Blower Works

An industrial blower is built with a cavity that is able to expand to hold more air volume. As a PD blower’s rotor turns, air is drawn through the inlet. The cavity then seals itself, trapping a certain volume of air, which is then moved around to the outlet side of the lobe and forced out against system pressure.

Types of Industrial Blowers

Industrial blowers have evolved to include a range of positive displacement blowers (sometimes called Roots blowers) and vacuum pumps specialized for various applications.  PD blowers maintain a fairly constant output flow regardless of pressure changes.

  • A Twin Lobe Rotary Blower features two rotors that rotate in opposite directions in a figure 8 configuration, trapping gas on the inlet side of the blower and exhausting it on the outlet side when the lobes rotate. Volumetric flow depends on the chamber size and rotation speed, and air is output in pulses. Because each lobe just clears the inside of the casing, this type of industrial blower ensures 100% oil free air.
  • A Tri Lobe Rotary Blower allow higher throughput than twin lobed blowers, with less noise and pulsation.
  • Helical Tri Lobe blowers are even quieter and more efficient.

How to Size an Industrial Blower

The first step in Positive Displacement blower sizing and selection is determining the right size blower for your application. When evaluating your performance needs, you’ll find that industrial blowers vary in four main criteria:

  1. pumping speed
  2. throughput rate
  3. vacuum
  4. pressure

PD blowers are most effective with high volumes, at low vacuums and pressures. Measurements vary with the size, type, and application of the positive displacement blower, and these are the general measurements:

  • CFM (cubic feet per minute) measures outlet displacement volume.
  • ICFM (inlet cubic feet per minute) refers to the amount of gas or other substance, by volume, that enters the blower during a given period of time.
  • Throughput rate is calculated by multiplying the pumping speed by the gas pressure at the inlet. The result is expressed as units of pressure·volume/unit time.
  • Vacuum is expressed in inches of mercury (Hg).
  • Pressure is measured in psig (pounds-force per square inch gauge).

The greatest return on investment comes from careful attention to industrial blower sizing and selection that exactly fits your application.

Main Criteria for Selecting a Positive Displacement Blower

Once size has been determined, there are other main factors buyers should consider for PD blower selection and sizing.


Industrial blowers are available to fit requirements for a range of applications, with specific features depending on the type of gas, temperature and conditions, and horizontal or vertical alignment.

Energy Efficiency

Energy consumption accounts for the majority of total ownership cost of an industrial blower, so choosing the right blower maximizes productivity and return on investment (ROI). An undersized blower that operates beyond its capacity will cost more to run. And an idle blower also wastes energy, consuming as much as 90% much energy as it would operating at a full load. The key to efficiency lies in correctly sizing the industrial blower to fit the requirements.

Some blowers offer high tech features that simplify industrial blower operation, automating energy efficiency measures to improve ROI. Energy efficiency features also help companies to address the reality of emission standards and Cap and Trade programs. Blower packages with variable speed technology can increase or decrease speed in direct correlation with airflow requirements, so they only use energy as it is needed. Measures like these can quickly pay for themselves.

Noise Reduction

Whether the industrial blower is installed on the floor or at an outside location, noise can be an important factor. To protect operators or to reduce noise pollution, some blowers employ technologies like a one-piece cylinder, dynamically balanced rotors, or tri-lobe designs. Comprehensive blower packages with custom air inlet filters and outlet silencers are also available.

Questions for Positive Displacement Blower Sizing and Selection

Carotek is an authorized distributor of Gardner Denver, Sutorbilt, and DuroFlow PD blowers. Carotek engineers are specially trained to assist with ordering the right blower for your application. When specifying a blower, reviewing these questions in advance will speed your industrial blower sizing and selection process.

  1. Reference values – Do you require U.S. or metric units?
  2. Gas Selection – Will you be moving air or gas mix?
  3. Gear Configuration – Do you need Horizontal or Vertical configuration?
  4. Application Type – Will you be using a pressure configuration or vacuum?
  5. Ambient Conditions – What are your values for Ambient Pressure and your unit of measure, Relative Humidity, and Ambient Temperature?
  6. Fahrenheit or Celsius? Pressure – What is the required pressure and your unit of measure?
  7. Flow – What is your required flow and your unit of measure? Relief Valve Setting?
  8. Additional Conditions to be considered:
    • Inlet Temperature
    • Inlet Pressure Drop
    • Power Limit
    • RPM Limit
    • Outlet Temperature Limit
    • Outlet Pressure Drop
    • Noise Limit

Once you have these details, contact us for expert selection assistance.  You can also browse our industrial blowers here.

Carotek a recognized industry leading supplier, service center, and maintenance facility for industrial blowers. Carotek offers extensive local product inventory, expertise, and support for a range of leading industrial blower products.