Chapter II - Head Type and Variable Area Flow Metering

Abstract

The discussion on head type flow metering based on international standard ISO 5167 starts with features and applications of the head type metering within industry. For each of flow elements, including different types of orifice, flow nozzle, sonic nozzle, Venturi, Dall tube, single and average Pitot tube, Krell bar, and Annubar, detailed features (advantages and disadvantages), applications, sizing details, design and construction details, pressure loss, and uncertainty calculation are discussed in this chapter. Installation details including straight length requirements as per standard (ISO 5167) are also described. Detailed discussions are presented on meter calibration methods such as volumetric and gravimetric methods, pipe prover tanks, etc. The discussion also includes special elements like the elbow meter and V-cone meter. Variable area flow meters, such as rotameter and piston meter, which operate with reversed head type flow elements, are also included in the discussions. For each case, mathematical treatment correction factors are provided for selection designing of the flow elements for varied operating conditions and applications. For each of these flow metering devices, specification sheets have been included for the use of the reader. Senior orifices, conditioning orifices, and restriction orifices are also discussed.