Pi Day 2015 – How Fan Engineers Celebrate

This month, we celebrate the wonderful mathematical constant π! Since 1988, physicists, mathematicians, engineers, and other number-enthusiasts have celebrated Pi Day on March 14 (3/14) every year. The event is marked with lively discussions about Pi, contests to see who can recite the most decimal places, and, of course, lots of pie!

2015 is a special year—we will mark a sequential time that includes the first ten digits of π on 3/14/15 at 9:26:53!

Pi (π or 3.141592653…) is especially important to ventilation engineering—it is at the core of many of our calculations. It represents the ratio of a circle’s circumference to its diameter. More often than not, a fan runs within a circular housing, making π an extremely important part of our calculations.

To figure out anything about a fan’s performance, you need to start with the fan’s airflow in CFM (cubic feet per minute). The formula is: CFM = (FPM * area). You’ll remember from high school geometry that the formula to calculate the area of a circle is A = πr2. Once you calculate the area of the fan’s face, you can multiply it by the fan’s velocity measured in feet per minute (FPM). This will give you the volume flow in CFM, which will allow you to make further inferences about your fan’s performance. How big of a motor do I need? How can I increase the air changes per minute? How will air density affect my fan’s performance? The answer to many of these questions starts with π!

Curious to know more? Check out the official Pi Day website to learn more about everyone’s favorite mathematical constant (sorry Tau). Although the official day is on a Saturday, we’ll be celebrating in the office the Friday before with some delicious pie for breakfast! How does your office celebrate Pi Day? Let us know in the comments.