Pipe flow calibration of Preston tubes of different diameters and relative lengths including recommendations on data presentation for best accuracy

Preston tubes of different diameters and length-to-diameter ratios were tested in incompressible pipe flow at Reynolds numbers of 60,000 to 300,000. The results show differences of the same order of magnitude as the various calibration curves suggested in the literature. Different ways of expressing the data have been considered and it is concluded that the traditional parameters are not suitable. Diagrams of the test equipment and conditions are provided. Tables of data and graphs of the performance obtained under various conditions are included.