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Fans are an important component of mechanically ventilated facilities for pig farms. They are the driving force behind the exchange of air that is necessary to create a healthy environment for pigs and associated farm employees.
Good quality pig farm fans are essential for proper performance of swine mechanical ventilation equipments. Inefficient fans can add to production cost in two ways. The most obvious cost is wasted energy that is expended while using an inefficient fan. Other cost can be due to poor air quality in the piggery. Fans that are inefficient or mismanaged may cause air quality diminishing, which will lead pigs more susceptible to disease and less-than-optimal growth and feed conversion. So selecting energy efficient fan is important for swine production.
But a common mistake is to select fans based in the fan diameter. Never assume that two fans of equal size will perform the same since different motors, curvature of blades and other attributes greatly influence the performance. To get the principle of fan selection, it is important to understand the following things:
Air delivery:
Air delivery is the amount of air that a fan will move under different conditions. It is expressed as volume of air-movement per unit time. The standard unit is cubic feet per minute (cfm).
Static pressure:
Static pressure is the difference in pressure that a ventilation fan creates between the inside and outside of a mechanically ventilated structure. Fans are used to create a vacuum within a pig house by exhausting air. The indoor environment, having a lower pressure than outdoors, will draw air in through inlets. This is called a negative pressure system.
Fan efficiency:
Fan efficiency is the amount of air delivery that a fan will provide per unit of electricity used, given in cubic feet per minute per watt (cfm/W). In general, small fans are less efficient than larger fans. Efficiencies range from about 5 cfm/W to 25 cfm/W.
Factors affecting fan performance:
The configuration in which a fan is installed and the manner in which it is maintained greatly affect its performance. Shutters reduce fan performance 10-25% but are necessary for periods when the fan is not operating. Dirty shutters and blades can reduce air delivery by as much as 40%. Regular cleaning and maintenance will keep shutters operating at their manufactured level of efficiency. Well maintained discharge cones increase fan efficiency by 15% or more. If belt-driven fans are used, check belt tension regularly. Loose belts will cause the fan to be less efficient and effective, perhaps by as much as 50%. An over-tight belt will cause undue wear on bearing.
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