Course description: Fans are machines for moving air and air-borne materials, and are widely used in industrial and commercial applications. Fans use billions of kilowatt-hours of energy each year. Fan reliability can be critical # for example, in material handling operations fan failure will often force a process stoppage. The importance of reliability may cause system designers to compensate for uncertainties by adding capacity to fans. Unfortunately, fans that are oversized for their service requirements do not operate at their best efficiency points. Paradoxically oversizing fan systems creates problems that can increase system operating costs while decreasing fan reliability.