3266 (RP-451) -- Airflow Measurements at Coil Faces with Vane Anememeters: Experimental Results PDF

The use of the k-factor procedure, using the rotating vane anemometer, has been found to predict volume flow rate through the coil with art accuracy of ±7%. A recommended reading pattern consisting of the standard and offset locations with a total of 38 readings was found to be most satisfactory. Less than 38 readings will give about the same accuracy In predicted volume flow rate, but the number of readings should never be less than 20. It is shown that the k-factor is a function of the average face velocity, rows of tubes deep, fins per inch, vertical tube spacing, and tube outside diameter. The results indicate that a 4-in-diameter head provides the most consistent results. Upstream disturbances such as elbows, partially blocked coils, dampers, and fan blasts generally did not affect the predicted flow velocity using the k-factor procedure.