The orifice plate discharge coefficient equation — further work

This paper describes the work undertaken to derive an improved orifice plate discharge coefficient equation based on the enlarged EEC/API database including the data collected in 50 and 600 mm pipes. It consists of several terms, each based on an understanding of the physics. An earlier version of this equation, based on a smaller database, was accepted at a meeting of EEC and APl flow measurement experts in New Orleans in 1988, and emphasis is placed on the two principal changes to the equation: improved tapping terms for low Reynolds number have been calculated; and an additional term for small orifice diameter has been obtained, and its physical basis in orifice edge roundness given.