Theactual capacity of a ventilator in a commercial poultry house can vary from the value that is given by the manufacturer. This is because the capacity depends on factors as wind direction, shutters, obstacles in the exhaust area, maintenance of the belt, engine and/or ventilator itself, as well as on factors as the actual negative pressure in the house.

When we want to make an estimation of the ventilation capacity of the actual ventilator, we can use a serie of air velocity measurements.

Draw an imaginairy cross over the surface of the ventilator. On every leg of the cross, measure the air velocity with an aenemometer on 1/3 and 2/3 of the distance from center to outside. Together with a measurement at the center of the ventilator, this gives a total of 9 air velocity measurements in m/s. Determine the average of the 9 measurements, and multiply this value with the surface of the ventilator (Pi r: 3,14 x radius in m x radius in m) in m2. This gives the ventilator capacity in m3/s. Multiply this value with 3600 to get an estimation of the ventilator capacity in m3 per hour.