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Altitude Effects – Fan Sizing and Operation




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 →


By David R. Olson, PE


Recently, I walked into a large gleaming natatorium. Only once before had I visited an indoor pool as large and impressive as this. What a spectacular facility this was! I could only imagine the starters signal while numerous finely tuned swimmers shot off the starting blocks at once, in search of gold and glory. I immediately noticed how muggy the air was. I pondered how this might affect the competing swimmers. The air within this natatorium did not remind me of a warm spring day in a mountain meadow. Not that it should, but the air was anything but fresh. Continue Reading →


By David Olson, PE, General Chairman of the 2013 Denver Annual Meeting

Outside, the snow has started to fall. It’s the kind that has big fluffy flakes, spiraling down to the ground. Good for snowmen and playful snowballs thrown from neighborhood forts. It gets dark early these days. For now though, it’s peaceful and quiet. Looking up at the newly lighted streetlights is hypnotizing. Thousands or millions of pure, cold snowflakes race to the ground, all unique. By morning, the city will be bathed, clean and white, new and fresh – reborn. The temperature drops. The wind suddenly gusts. The temperature outside is plunging rapidly. Now is the time to find a sheltered spot for solace and relief. Denver’s homeless population has a reason to smile tonight thanks to the recently completed ASHRAE sustainable footprint project at the Denver Rescue Mission. Tomorrow morning grateful men will leave the mission for the day’s work, well rested, clean and fed. Continue Reading →