Halton offers a variety of means for determining the exhaust flow. The Test and Balancing Ports (T.A.B.) are integrated into all Capture Jet hoods. These ports are to be used in determining both the exhaust and Capture Jet air flows. Each incremental size of hoods has been tested through the range of operable air flows and a curve has been generated showing airflow as a function of pressure drop across the TAB ports to give an accurate reading of airflow.