ASME International

Measurement of Fluid Flow in Pipes Using Orifice, Nozzle, and Venturi
 N MFC-3M ADD

Annotation

This Standard specifies the geometry and method of use (installation and operating conditions) for pressure differential devices (including, but not limited to, orifice plates, flow nozzles, and venturi tubes) when installed in a closed conduit running full and used to determine the flow-rate of the fluid flowing in the conduit. This Standard applies to pressure differential devices in which the flow remains subsonic throughout the measuring section and where the fluid is considered as single-phase. The Standard is limited to single-phase Newtonian fluid flow in which the flow can be considered sufficiently free from pulsation effects. It gives information for calculating the flow-rate and the associated uncertainty when each of these devices is used within specified limits of pipe size and Reynolds number.

This Standard covers flow meters that operate on the principle of a local change in flow velocity and/or flow parameters caused by meter geometry, resulting in a corresponding change of pressure between two set locations. Although there are several types of differential pressure meters available, it is the purpose of this Standard to address the applications of each meter and not to endorse any specific meter. The operating principle of a pressure differential flow meter is based on two physical laws: conservation of energy and conservation of mass, realized when changes in flow cross-sectional area and/or flow path result in a change of pressure. This differential pressure, in turn, is a function of the flow velocity, fluid path, and fluid properties.

Included within the scope of this Standard are devices for which direct calibration experiments have been made, sufficient in number and data coverage, to enable valid systems of application to be based on their results and coefficients to be given with known uncertainties.