Effect of Fittings on Volumetric Airflow Measurements (RP-1245): Single-Path Duct Disturbances

The objectives of this presentation are to quantify the influence of several single-path duct disturbances on volumetric air flow rate measurements using traversing techniques, and to develop guidelines for field technicians to assist them in making more accurate volumetric airflow measurements in rectangular ducts during test and balance operations. Data are presented that attempt to quantify the error caused by the distance from single-path disturbances (straight ducts, elbows, 60º and 90º transitions) to a given airflow measurement (traverse) location, using both thermal anemometer and Pitot-static probes. The traversing algorithms used were the Log-Tchebycheff (LT) method and Equal Area (EA) method.