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ASME MFC-1-2014 pdf download

ASME MFC-1-2014 pdf download.Glossary of Terms Used in the Measurement of Fluid Flow in Pipes.
1 GENERAL 1.1 Scope This Standard consists of a collection of definitions of those terms that pertain to the measurement of fluid flow in pipes. The definitions provided also give guid- ance for recommended usage in the application of flow measurement devices. 1.2 Organization This Standardis organized alphabeticlly. Symbols nor- mally applied to various quantities are tabulated in section 3. 1.3 References This Standard was compiled from many sources, including various reports and standards from The American Society of Mechanical Engineers (ASME), the American Gas Association (AGA), the American Petroleum Institute (API), the International Society of Automation (ISA), the British Standards Institute (BSI), the International Organization for Standardization (ISO), the National Institute for Standards and Technology (NIST), and the International Organization of Legal Metrology (OIML). 2 GLOSSARY OF TERMS absolute pressure: algebraic sum of the atmospheric pres- sure and gauge pressure. absolute static pressure ofa fluid: static pressure of a fluid measured with reference to a perfect vacuum. acceptance test: the evaluating action(s) to determine ifan instrument satisfactorily meets its performance criteria, permitting the owner/purchaser to formally accept it from the supplier. accuracy ofmeasurement: the extent to which a given mea- surement agrees with a reference for that measurement; often used by manufacturers to express the performance characteristics of a device. NOTE: “Accuracy” is not the same as “uncertainty” (see “uncer- tainty of measurement”). acoustic matching layer: material comprising one or more layers, selected to maximize the acoustic coupling coeffi- cient between two media. 1 acoustic path: the path that the acoustic signals follow as they propagate through the measurement section between the transducer elements. acoustic ratio: the differential pressure ratio divided by the isentropic exponent (compressible fluid). air: mixture of gases and associated water vapor sur- rounding the earth; dry air plus its associated water vapor. The termisused synonymouslywithatmosphere. air, dry: mixture of dry gases present in the atmosphere. ambient temperature: temperature ofthe atmosphere mea- sured in the immediate vicinity of the point of measure- ment and unaffected by wind or other atmospheric phenomena. annular chamber: piezometer ring integral with the pipe or the primary device that simplifies the construction of annular pressure taps. annular space: area between the tapered tube and the float that normally increases as the float rises. area meters: flowmeter in which a variation in the cross section of the fluid stream under constant head is used as an indication of the rate of flow, e.g., a float is sus- pended in a vertical tapered tube and as the fluid flow rate changes, the positionofthefloatinthe tube changes. arithmeticmean: the sumofvalues divided bythe number of values, also called “average.” NOTES: (1) The term “mean” is used generally when referring to a popula- tion parameter, and the term, “average,” when referring to the result of a calculation on the data obtained in a sample. (2) The average of a simple random sample taken from a popula- tion is an unbiased estimator of the mean of this population. Other estimators, such as the geometric or harmonic mean, the median, or the mode are sometimes used. atmospheric pressure: force per unit area exerted by the atmosphere. NOTE: Standard atmospheric pressure is 760 mm of mercury at 0°C. This is equivalent to 101.325 kPa and 14.696 psia.
bias: the difference between the average of all possible measured values and the true value; the systematic error or fixed error that characterizes every member of a set of measurements; sometimes called “bias error” or “sys- tematic error,” see Fig. 2. NOTE: The bias cannot be reduced by increasing the number of measurements taken under fixed flow conditions. bias limit: the estimate of the upper limit of the true bias error. bias of estimator: the deviation of the expectation of an estimator of a parameter from the true value of this parameter. This expression may also be used in a wider sense to designate the lack of coincidence between the expectation of an estimator and the true value of the parameter. bivariate correction: a correction that is a function of two independent parameters. bluffbody: nonstreamlined body used in vortex flowmet- ers to produce and shed vortices. bore area: the minimum cross-sectional flow area of an orifice, nozzle, or venturi; sometimes called the throat area.

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