Performance evaluation of handheld airflow instruments applied to commercial kitchen exhaust systems

Laboratory measurements have been made to determine the accuracy of several handheld instruments when used to measure the exhaust airflow rates during commercial kitchen airflow balancing. The instruments included 4 in. (0.1 m) and 2.75 in. (0.07 m) rotating vane anemometers, a hot film anemometer, a velocity grid, and flow hoods with 2 x 2 ft (0.61 x 0.61 m) and 2 x 4 ft (0.61 x 1.22 m) hoods. Grease filter configurations included conventional baffle filters, cyclone filters, and slot filter s mounted in an 8 ft (2.4 m) canopy exhaust hood. Exhaust airflow rate measurements were made at approximately 2000, 3000, and 4000 scfm (0.94, 1.4, and 1.9 m³/s) for each instrument and each filter type. Measurements were made with a gas fryer, half-size electric oven, and a gas underfired broiler idling (hot tests) and turned off (cold tests) to determine the influence of hot appliances. Flow rates determined using calibrated flow nozzles in the supply air system agreed to within a few percentage points of those measured using the flow hoods. The other instruments generally did not provide accurate results unless an appropriate correction factor, or K-factor, was used.