Theoretical uncertainty of orifice flow measurement
- Daniel Flow Products, Inc., Houston, TX (United States)
Orifice meters are the most common meters used for fluid flow measurement, especially for measuring hydrocarbons. Meters are rugged, mechanically simple, and well suited for field use under extreme weather conditions. Because of their long history of use and dominance in the fluid flow measurement, their designs, installation requirements, and equations for flow rate calculation have been standardized by different organizations in the United States and internationally. These standards provide the guideline for the users to achieve accurate flow measurement. and minimize measurement uncertainty. This paper discusses different factors that contribute to the measurement inaccuracy and provide an awareness to minimize or eliminate these errors. Many factors which influence the overall measurement uncertainty are associated with the orifice meter application. Major contributors to measurement uncertainty include the predictability of flow profile, fluid properties at flowing condition, precision of empirical equation for discharge coefficient, manufacturing tolerances in meter components, and the uncertainty associated with secondary devices monitoring the static line pressure, differential pressure across the orifice plate, flowing temperature, etc. Major factors contributing to the measurement uncertainty for a thin, concentric, square-edged orifice flowmeter are as follows: (a) Tolerances in prediction of coefficient of discharge, (b) Predictability in defining the physical properties of the flowing fluid, (c) Fluid flow condition, (d) Construction tolerances in meter components, (e) Uncertainty of secondary devices/instrumentation, and (f) Data reduction and computation. Different factors under each of the above areas are discussed with precautionary measures and installation procedures to minimize or eliminate measurement uncertainty.
- OSTI ID:
- 146372
- Report Number(s):
- CONF-950553--
- Country of Publication:
- United States
- Language:
- English
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