In buildings and industrial facilities, transport of air is necessary for cooling, heating, ventilating, and manufacturing processes. For an airtransportprocess, accurate measurement of airflow is related to the comfort level of buildings and the realization of high-quality products. Measurement of airflow is difficult because of complicated flow characteristics and nonuniform velocity distribution. In this study, we have conducted comparative analysis of typical flowmeters used in the industry for measuring airflow and intend to propose a new type of portable multi-nozzle airflow meter with exit pressure control that is more accurate than the existing on-site flow measurement devices. A stationary multi-nozzle flow measurement system, FM- 1000, was built following the ANSI/ASHRAE 51-1999 standard (ANSI/ASHRAE 1999) and compared with a mass flowmeter that is considered accurate and that confirmed that the average deviation was 0.36%. Using this stationary multi nozzle flow measurement system, performances of portable anemometers and flowmeters that are widely used for on-site flow rate measurements were tested. Due to limitations of these portable measuring devices, average errors were 34.1% for vane type, 37.4% for hot wire type and 9.8% for hood type. A portable small scale multi nozzle flowmeter with exit pressure control that was developed in this study has advantages of easy handling and accurate measurement in the field and showed an error of only 0.93%.
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