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

On-site air flow measurements of domesticventilation systems with using funnel type airflow measurement instrument which isgenerally used in Japan, has been reported themeasurement difficulties due to the terminaldevices' installed location, the existence offurniture in the vicinity or skill of the measurer.Hence investigations on the measurementmethod, which has lesser influences of thedisturbance, have been needed. Therefore, thisstudy compares on-site air flow measurementwith funnel method and pressure differencemethod which is considered as on of thesolution. From the on-site measurement results,the pressure difference method approximatelyaccords with the funnel method with less than*5% relative errors on exhaust only ventilationsystems employing flexible ducts, whosediameter is 50mm. Moreover, laboratory testswith pilot air terminal devices, which apply tothe pressure difference method and can beconnected to 50mm, 75mm and 100mmdiameters duct, were operated under supply andextract conditions in order to obtain the air flowcharacteristics data under diverse conditions.The experimental results indicate that air flowrate measured with every terminal devicesshow approximately same as reference air flowrate under the extract conditions and the airflow rate measured with the terminal deviceconnected to lOOinm diameters duct showsrelatively same as reference air flow rate underthe supply conditions.