The direction of flow along the centerline of several sections of the inlet duct of a centrifugal pump was determined using a hot wire anemometer. In contrast to other tests of this kind, the pump was operated with air to facilitate the measurements. This investigation is part of a program at the U. S. Naval Postgraduate School to evaluate the performance of liquid pumps with air in order to apply aerodynamic measuring methods and equipment to the task. Data were taken with the pump operating at different points on the characteristic curve. The flow direction data are presented as a function of position in the intake duct for various operating conditions. Prerotation was observed, the character of which was in agreement with theoretical predictions in that prerotation was in the same direction as the impeller rotation at the low flow rates and in the opposite direction at the high flow rates. Backflow near the periphery of the duct was observed at the low flow rates. (Author)