Basics of ventilation
Updated: Aug 22, 2019
What is Fan Efficiency? Fan Efficiency is the amount of air delivery per unit of electrical power used, given in cubic feet per minute per watt (cfm/W) or cubic meter per hour per watt (m³/h·W). Generally, small fans are less efficient than larger fans, and belt drive fans are less efficient than direct drive fans.
How Fans are rated? Fans should be rated by an independent lab to show airflow and efficiency base on a range of different static pressures. Two of the most influential fan testing labs are Bioenvironmental and Structural Systems (BESS) lab at the University of Illinois and Air Movement and Control Association (AMCA).
What are fans guard for? Guards can protect people from the fan and also the fan from intruding objects. Generally, they have minimal effect on fan performance and should always be installed where applicable. Better be safe, than sorry!
What are fans shutter for? They are mainly installed on the exhaust fan. During winter, some farmers prefer to use only a few fans, and the others are shut. Shutters can substantially reduce fan performance but they are necessary for times when fans are not operating to prevent back drafting Dirty shutters and blades can significantly reduce air flow, so regular cleaning and maintenance are needed to keep fans running at their original efficiency. Dirty shutters and blades can substantially reduce air flow, so regular cleaning and support are required to keep fans operating at their initial energy.
What is the use of a cone? Fan discharge cones can increase fan efficiency, also they serve as weather hood to prevent rains or snow from getting inside the fan housing.