Abstract
This paper is devoted to a proposed method for determining the volume of air handled by any fan which is provided with either inlet or discharge ducts. The proposal is to use pitot tubes for capacities near the wide-open condition and square-edged inlet or discharge orifices for lower capacities down to the no-flow condition. To make the pitot-tube measurements accurate, a standard form of pitot tube is suggested, based on the investigations of Ower and the unpublished researches of Merriam and Spaulding at Worcester Polytechnic Institute. The coefficients of Ebaugh and Whitfield are suggested for use with inlet orifices, while those of Stach are suggested for discharge orifices used with flange pressure taps on the approach side. The alternative procedure of using an impact tube with the discharge orifice is discussed, but coefficients are not as yet available.
