# I How to calculate air volume of a fan using pressure?

1. Oct 14, 2016

### Raphael Gonzalez

How can you calculate air volume in cubic feet per minute through a fan when the only data available is pressure drop and fan diameter?

For example, How many cubic feet per minute of air is a fan blowing if it has a diameter of 20" and a pressure drop of -50 pascals?

2. Oct 14, 2016

### Staff: Mentor

Welcome to PF!

That's pressure rise you mean, but sorry, that isn't enough information to determine the airflow.

3. Oct 14, 2016

### rcgldr

Generally there's a pressure jump (with little change in speed) of the affected air as it passes through the plane of the rotating fan. There are related NASA articles about propellers which should allow you to solve for velocity at the fan (and therefore volume flow at the fan), ... , some what idealized. Assume that V0 is zero, and that density is constant.

http://www.grc.nasa.gov/WWW/K-12/airplane/propanl.html

http://www.grc.nasa.gov/WWW/K-12/airplane/propth.html

Last edited: Oct 14, 2016