Critical Information for Proper Fan Selection

You want the best fan? There’s no way of knowing what that is until we know what you actually need for your specific application. The choices could seem endless until you put four critical pieces of information together. Armed with the right specs, an application engineer can identify a short list of options, and fan selection becomes very clear to us from there.

Proper fan selection depends on four key inputs:

  • Volumetric Flow Rate
  • Fan Static Pressure
  • Inlet Air Density
  • Intended Fan Duty

Fan Selection Criteria Overview

Volumetric Flow Rate

The most basic and obvious piece of information for fan selection is the rate of air flow through the fan. The volumetric flow rate measures the volume of air at the fan inlet over a period of time. We typically calculate and specify the air flow in units of Cubic Feet per Minute (CFM).

Fan Static Pressure

Fan Static Pressure is calculated as the difference between the pressure required at the fan outlet and the pressure at the fan inlet plus velocity pressure. It is measured with a water gauge and commonly reported in inches of water column (wc) or water gauge (wg). Learn more.

Inlet Air Density

The third piece of information we need for fan selection is inlet air density. We calculate inlet air density using three key factors (the 4th factor has minimal impact on most applications):

  • Temperature
  • Elevation of the installation
  • Fan inlet pressure
  • Moisture content

Standard conditions are considered to be 70 degrees Fahrenheit, with an elevation of zero feet (sea level) and an inlet pressure of zero inches of water column, giving a density of 0.075 pounds per feet cubed. Learn more.

Intended Fan Duty

The last piece of information we need to properly advise you on fan selection is what duty you expect your fan to handle. It’s often more than just air that moves through a fan. We need to know what your fan will be dealing with, for example:

  • Clean air
  • Saturated gas
  • Material particles
  • Dirty air

Hear it from the Application Engineer

Senior Application Engineer Chet White provides an overview of what we need to know to properly help with fan selection in this 2-minute video.

When you’re ready to start your project, reach out and connect with one of our application engineers to discuss the details of your specification.

Related Content: Details on the Variables Needed for Fan Selection

To see more information on some of the variables outlined above, take a look at a couple other videos:

We welcome comments and questions via our LinkedIn Page, and you can always Contact Us or Request a Quote for more details.