Elevated Temperature and Altitudes: Performance ratings linked to on the Fan Types page are based on standard air at 70 degrees F. and 29.92 inches barometric pressure and weighing 0.075 pounds per cubic foot. When air temperatures other than 70 degrees F. and/or altitude other than sea level is involved, it is necessary to correct catalogue ratings for fan speed and horsepower.

Example:

Assume an industrial fan with EA-11 wheel for:
- 2900 CFM.
- 4500 max. O.V.
- 6" SP
- 200° F.
- 5000 altitude.

Proceed as follows:

1. Density factor from table below = 0.668
2. Performace table static pressure = 6" ÷ 0.668 = 9'
3. From performance table: EA-1 Size 11
   - CFM = 2904
   - SP = 9"
   - RPM = 2286
   - BHP = 6.07
4. Correct performance table SP and BHP as follows: - Fan CFM = 2904
   - Fan SP = 9" x 0.668 = 6"
   - Fan RPM = 2286
   - Fan BHP = 6.07 x 0.668 = 4.05

Air Density Factors for Various Temperatures and Altitudes: