ASME MFC-10M:2000 pdf download

ASME MFC-10M:2000 pdf download.METHOD FOR ESTABLISHING INSTALLATION EFFECTS ON FLOWMETERS
Under certain circumstances, flowmeter coefficient shifts and calibration errors caused by installation effects (pipe flow phenomena), i.e., flow pattern, pulsations, etc., can be significant. These changes can be most severe when a flowmeter is moved from an installation in which there are long lengths of straight pipe upstream and downstream of the meter, to an installation where the meter is mounted close to a disturbing pipeline element such as an elbow, valve, or pump. Because different types of flowmeters can be affected differently by the same flow pattern, it becomes important to know the flow pattern sensitivity of a given flowmeter in order to properly use it. This pattern sensitivity is established by first determining the performance of a meter in a reference installation and then determining the variations in the meter’s performance caused by other installation conditions. When preparing programs to test for installation effects, it should be realized that the purpose of the tests is to uncover effects that change the metering performance. These effects may be stated as a function of the flow profile at the meter, the pertinent parameters such as Reynolds number, relative roughness, etc., and the type of disturbing element, the flow condition entering it, and the distance separating it from the meter. When analyzing installation effects, the changes in the metering performance of a flowmeter are obtained by evaluating the signature (e.g., flow coefficient versus Reynolds number), bias, and precision of a meter when it is flow calibrated in reference and nonreference piping.
3 DEFINITIONS
The following definitions are given for terms used in some special sense or whose meaning seems useful to emphasize. A more comprehensive list of definitions and symbols applicable to the measurement of fluid flow in closed conduits can be found in ASME MFC- 1M and ASME MFC-2M. bias limit (B): the estimate of the upper limit of the true bias error, ? (see ASME MFC-2M for further details on this subject). fully developed axial flow profile: an axial velocity distribution that does not change with axial position along a pipe of constant cross-section. identical: differing by less than the uncertainty interval for the measurements. It is assumed that every reason- able effort is made to eliminate significant bias and precision errors. precision (also known as random error): the closeness of agreement between the results obtained at the same installation by applying the experimental procedure several times under prescribed conditions. The smaller the random part of the experimental errors which affect the results, the more precise the procedure (see ASME MFC-2M). precision index: an estimate of the standard deviation of repeated measurements of the same thing, e.g., meter output at constant flowing conditions.
4 GENERAL GUIDELINES
The following guidelines should be adhered to in establishing installation effects on flowmeters. (a) Care must be taken to achieve a proper and repeatable alignment between the meter and the adjacent piping at both inlet and outlet of the meter. Alignment of the meter per appropriate standards such as ASME MFC-12M or AGA9, etc., or according to manufacturers recommendations is recommended. (b) The flow condition should be one of a conduit running full and steady with a homogeneous, single phase fluid. Flow is considered steady if, within the measurement uncertainty, it is constant in time aside from variations related to turbulence generated within the piping. (c) The tests outlined in this Standard should cover the pertinent range of fluid flow rates, Reynolds num- bers, etc., of the meter to be evaluated. NOTE: This requirement can be satisfied by stating the range of pertinent nondimensionalized parameters over which the data were obtained (see Section 7). (d) To avoid missing periodic spatial flow variations, measurements should be made at pipe lengths that are not integer multiples of each other. (e) All calibrations should be performed at the same flow conditions or as close as practical to the same conditions when comparing different test runs. When reducing data, corrections can be made via an indepen- dent parameter such as Reynolds number when it can be shown that the overall effects of the different fluid conditions (temperature, pressure, etc.) and/or the fluid properties (density, viscosity, etc.) on the tested flow- meter size and type are known and have been ac- counted for. (f) All raw calibration data should be recorded and retained.