How does fan and blower performance change at 1,000 and 2,000 meters altitude?
The pressure developed by an air moving device will change proportionally with the air density if the RPM is kept constant. An air moving device powered by an electric motor will change RPM with a change in altitude due to the change in density (less load at higher altitude). This RPM change generally will compensate for altitude changes. The exception is for AC motors that are designed to run very close to synchronous speed at sea level. These will not change the speed with altitude change and will therefore produce less pressure at high altitudes.
