BS 7118-2 is the second part of an International Standard that discusses the aspects of measurement of fluid flow.
BS 7118-2 describes the procedures for fitting a quadratic, cubic, or higher degree polynomial expression to a non-linear set of calibration data, using the least-squares criterion, and assessing the uncertainty associated with the resulting calibration curve.
BS 7118-2 considers only the use of polynomials with powers that are integers. Because it is not practicable to carry out this type of curve fitting and assessment of uncertainty without using a computer, it is assumed in BS 7118-2 that the user has access to one. In many cases, it is possible to use standard routines available on most computers; an alternative to the FORTRAN program listed in BS 7118-2 is used. Examples of the use of these methods are given in BS 7118-2.
Note 1: Extrapolation beyond the range of the data is not permitted.
Note 2: The method of fitting a straight line to flow measurement calibration data and assessing the uncertainty in the calibration is dealt with in ISO 7066-1.
Note 3: ISO 7066-2 deals with the case where a straight line is inadequate for representing the calibration data.
BS 7118-2 on flow measurement devices is relevant to:
Flow measurement is an action to measure the flow of liquids, gases, and vapours using a flow measurement instrument and device, which measures the rate of flow or the quantity of flow.
BS 7118-2 lays out the methodology to assess the non-linear calibration relationships of flow measurement devices. BS 7118-2 assists with the method of least squares, i.e., the technique used to compute the coefficients of a particular form of an equation that is chosen for fitting a curve to data. BS 7118-2 gives you detailed information about the terms, definitions, and symbols, and explains the principle of the test.
BS 7118-2 elaborates the particulars of the curve fitting and gives the computational methods and selection process for the optimum degree of fit. BS 7118-2 also aids in calculating the uncertainty of the components of flow measurement devices.
Overall, BS 7118-2 is useful as it provides guidance on the calibration and use of flow measurement devices that can be beneficial for your business and can also help you to expand your business globally.