API MPMS 22.2-2017 pdf download.Manual of Petroleum Measurement Standards Chapter 22—Testing Protocol Section 2—Differential Pressure Flow Measurement Devices.
1 Scope 1.1 General The testing protocol is limited to single-phase Newtonian fluid flow, and no consideration is given to pulsation effects. Further revisions of this document may include the testing of such meters in wet gas or multi-phase service and the effects of pulsation. This standard does not address testing protocols of those devices that operate on the principle of critical or choked flow condition of fluids. The testing protocol covers any flow meter operating on the principle of a local change in flow velocity caused by the meter geometry, giving a corresponding change of pressure between two reference locations. There are several types of differential pressure meters available to industry. It is the purpose of this standard to illustrate the range of applications of each meter design and not to endorse any specific meter. The basic principle of operation of the flow measuring devices follows the physical laws relating to the conservation of energy and mass for the fluid flows through the device. Any API MPMS document addressing a specific type or design of differential pressure flow measuring device will supersede the requirements of this document for that type or design. An example of such standards are all parts of API MPMS, Chapter 14.3, Concentric, Square-Edged Orifice Meters. 1.2 Differential Pressure or Head-type Flow Meters The operating principle of a differential pressure flow meter is based on two physical laws – the conservation of energy and conservation of mass, where changes in flow cross-sectional area and/or flow path produce a differential pressure, which is a function of the flow velocity, fluid path, and fluid properties. This testing protocol applies to all types of differential-pressure meters. The examples presented below illustrate some of the applicable meter designs; however, this protocol is not limited to these meter types.
2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. API MPMS Chapter 14, Natural Gas Fluids Measurement, Section 3, Concentric, Square-edged Orifice Meters, Part 1, General Equations and Uncertainty Guidelines API MPMS Chapter 14, Natural Gas Fluids Measurement, Section 3, Concentric, Square-edged Orifice Meters, Part 2, Specification and Installation Requirements ASME B46.1-2002, Surface Texture (Surface Roughness, Waviness, and Lay) ISO GUIDE 98-3: Uncertainty of measurement—Part 3: Guide to expression of uncertainty in measurement (GUM:1995) 3 Terms and Definitions The definitions are given to emphasize and clarify the particular meaning of terms as used in this document. 3.1 area ratio (A r ) The minimum unrestricted area at the primary device divided by the cross-sectional area of the meter pipe or meter body, as applicable. 3.2 Beta ratio (β) The ratio of the orifice bore to the internal diameter of the meter tube. 3.3 calibration facility A flow laboratory used to determine the discharge coefficient of individual meters provided for field use by a manufacturer. 3.3.1 independent calibration facility A calibration facility that is not owned, operated, or affiliated with the manufacturer. 3.3.2 in-house calibration facility A calibration facility that is owned, operated, or affiliated with the manufacturer. 3.4 critical dimension The dimension (including parameters such as sharpness or surface finish) of any part of the meter that could affect the discharge coefficient.
3.6 discharge coefficient (C d ) The ratio of the actual flow rate through a primary device to the theoretical flow rate. The theoretical flow rate corresponds to the flow rate without any loss of energy due to friction. 3.6.1 tested discharge coefficient The discharge coefficient determined at a specific Reynolds number and configuration during the testing required by this protocol. 3.6.2 predicted discharge coefficient The discharge coefficient provided by the manufacturer, normally based on a flow calibration of the meter under baseline conditions. The predicted C d is typically presented as an equation that curve-fits the individual discharge coefficients determined during the flow calibration of the meter or as a fixed value representing the average discharge coefficient determined during the flow calibration of the meter. 3.7 dynamic, total, or stagnation pressure (P st ) For an elemental fluid streamline, the increase in pressure above the static pressure that would result from the complete isentropic transformation of the kinetic energy of the fluid into pressure energy. It is equal to , if the fluid is incompressible, where is ρ the density of the fluid and v is the velocity. 3.8 flow conditioner A device installed upstream of the primary device, designed to minimize the effect of flow profile distortions on the discharge coefficient. 3.9 flowing temperature (T f ) The measurement of heat intensity of the flowing gas.