Applications and Calibrations of the FANS and Traverse Methods for Barn Airflow Rate Measurement

Accurate and repeatable fan airflow rate measurement is critical for aerial emission monitoring at mechanically ventilated animal barns. This paper evaluates three techniques for on-farm fan airflow rate measurements. The drifts of eight units of a USDA-invented portable airflow rate measurement system, referred to as the Fan Airflow Numeration System (FANS), was studied using an industry standard airflow measurement chamber. The FANS units were applied in the field frequently, and were part of the two-year National Air Emissions Monitoring Study. The calibration results indicated that the FANS units showed little drift (-1.94% to 2.58% difference from actual values). The airflow penalty (reduction of airflow) of the FANS to the ventilation fan airflow rate was 3.0% (lower than without FANS), and the penalty was even higher for lower pressure, and when the FANS was not centered to the ventilation fan during measurement.