In buildings and industrial facilities, transport of air isnecessary for cooling, heating, ventilating, and manufacturingprocesses. For an air transport process, accurate measurementof airflow is related to the comfort level of buildings and therealization of high-quality products. Measurement of airflowis difficult because of complicated flow characteristics andnonuniform velocity distribution. In this study, we haveconducted comparative analysis of typical flowmeters used inthe industry for measuring airflow and intend to propose a newtype of portable multi-nozzle airflow meter with exit pressurecontrol that is more accurate than the existing on-site flowmeasurement 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 flowmeterthat is considered accurate and that confirmed that theaverage deviation was 0.36%. Using this stationary multinozzle flow measurement system, performances of portableanemometers and flowmeters that are widely used for on-siteflow rate measurements were tested. Due to limitations of theseportable measuring devices, average errors were 34.1% forvane type, 37.4% for hot wire type and 9.8% for hood type. Aportable small scale multi nozzle flowmeter with exit pressurecontrol that was developed in this study has advantages of easyhandling and accurate measurement in the field and showed anerror of only 0.93%.