An in-situ method of airflow measurement for fans and ventilation systems

摘要

An airflow measurement apparatus comprises an enclosure 38 having at least one wall defining a flow channel. The channel has a first open end defining an inlet and a second open end defining an outlet. An air velocity measurement device 34 is located at a fixed location along the length of the channel. The enclosure and the measurement device are configured such that the cross sectional area a of the enclosure at the location of the measurement device is greater than the cross sectional area of the measurement device across the same plane, with the ratio of the two cross sectional areas being fixed and pre-defined. A support 40 holds the air velocity measurement device in the fixed position such that a space is defined around and between the measurement device and the wall of the channel. The cross sectional area may be constant along the length of the channel. Te measurement device may be an anemometer. The apparatus may surround a vent 24 that passes through walls 26, 30 of a building. The airflow may be determined from the product of the measured air velocity and the predetermined cross section area. A calibration method is also claimed.