ALTITUDE EFFECTS
-
FAN SIZING AND OPERATION
DAVID R. OLSON, PE
Things are different when you are over a mile above sea level. There’s less air at this altitude. The density of the atmosphere at sea level is 0.075 pounds per cubic foot. That means that every cubic foot of 70°F air weighs 0.075 pounds with a barometric pressure of 29.92” Hg (14.7 lbs/in2). In Denver, Colorado with an elevation of 5,280 feet above sea level, the barometric pressure equals about 27.8” Hg (12.04 lbs/in2). Denver air at 70°F has a density of 0.0617 pounds per cubic foot. That means that there is only 82.3% of the air in Denver as there is at sea level locations. The air density in the Colorado mountains is even less. The altitude of Aspen, Colorado is 7,928 feet above sea level. Consequently, the air density there is just less than 0.0554 pounds per cubic foot, or about 73.9% of that found at sea level. The reduced air density experienced at high elevations does not just make it more difficult for individuals to breathe; it impacts the operation and performance of all sorts of mechanical equipment. This article will focus on the impacts of altitude on the sizing of fans. Continue Reading →