Investigation of On-site Measurement of Air Flow Rate on Compact Air Terminal Devices

摘要

On-site air flow measurements of domestic ventilation systems with using funnel type air flow measurement instrument which is generally used in Japan, has been reported the measurement difficulties due to the terminal devices' installed location, the existence of furniture in the vicinity or skill of the measurer. Hence investigations on the measurement method, which has lesser influences of the disturbance, have been needed. Therefore, this study compares on-site air flow measurement with funnel method and pressure difference method which is considered as on of the solution. From the on-site measurement results, the pressure difference method approximately accords with the funnel method with less than ±5% relative errors on exhaust only ventilation systems employing flexible ducts, whose diameter is 50mm. Moreover, laboratory tests with pilot air terminal devices, which apply to the pressure difference method and can be connected to 50mm, 75mm and 100mm diameters duct, were operated under supply and extract conditions in order to obtain the air flow characteristics data under diverse conditions. The experimental results indicate that air flow rate measured with every terminal devices show approximately same as reference air flow rate under the extract conditions and the air flow rate measured with the terminal device connected to 100mm diameters duct shows relatively same as reference air flow rate under the supply conditions.