ISO 91:2017

ISO 91:2017 pdf free.Petroleum and related products – Temperature and pressure volume correction factors (petroleum measurement tables) and standard reference conditions.
4 Sources and usage guidelines for volume correction factors
4.1 Source of volume correction factors
For the purpose of custody transfer in accordance with this document, reference shall be made to API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, including Addendum 1-2007. API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, including Addendum 1-2007,recognizes three distinct commodity groups: crude oil, refined products, and lubricating oils. A special application category is also included which provides volume correction based on the input of an experimentally derived coefficient of thermal expansion.
NOTE 1 Additional API volume correction factor standards have subsequently been published or are under development for particular applications. See Annex D.
API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 2 00/04 provides general procedures for the conversion of input data to generate the corrected values at the user specified base temperature and pressure using the effect of temperature on the liquid (CTL), the compressibility coefficient (F,,), the correction for the effect of pressure on the liquid (CPL), or the correction for temperature and pressure of a liquid (CTPL), in a form that is consistent with the computation procedures used to generate VCF values. Two sets of procedures are given for computing the volume correction factor: one set for data expressed in U.S. customary units (temperature in degrees Fahrenheit, pressure in pounds per square inch gauge), the other for the metric system of units (temperature in degrees Celsius, pressure in kilopascals). In contrast to API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80, the metric procedures require the procedure for U.S. customary units be used first to compute density at 60 °F. This value is then further corrected to give the metric output.
For density/weight/volume intraconversion, reference shall be made to API MPMS Chapter 11.5 Part 1 to Part 3/Adjunct to ASTM D1250-08 and IP 200/08. These standards provide conversion of measurements from one system of units to another for both in vacuo and in air values.
For NGL and LPG, reference shall be made to API MPMS Chapter 11.2.4-2007/GPA Technical Publication TP-27-2007. The implementation procedures describe how to calculate the CTL given an appropriate density factor at basis temperature and an observed temperature, and calculate the appropriate density factor at basis temperature given a relative density at an observed temperature. The implementation procedures are presented in pairs by base temperature. First, the procedures for Tables 23E and 24E of API MPMS Chapter 11.2.4-2007/GPA TP-27-2007 at a 60 °F base temperature are given. The procedure for Table 23E makes use of the procedure described in Table 24E, thus Table 24E is presented first. These are followed by procedures for Table 54E and Table 53E at a base temperature of 15 °C, which themselves make use of the procedures in Table 23E and Table 24E; these in turn are followed by the procedures for Table 60E and Table 59E at a base temperature of 20 °C, which also make use of the procedures described in Table 23E and Table 24E.
To correct NGL and LPG volumes metered under pressure to the corresponding volumes under equilibrium pressure for the process temperature at the meter, reference shall be made to API MPMS Chapter 11.2.2-1986 (including Errata June 1996) or API MPMS Chapter 11.2.2M-1986 or if outside of the density range of these standards, API MPMS Chapter 11.2.1-1984 or API MPMS Chapter 11.2.1M-1984.
These methods require a knowledge of the equilibrium bubble point pressure (vapour pressure) at the measured conditions. However, the vapour pressure of the process liquid is generally not measured. The vapour pressure can also be calculated from compositional information, but the composition is not always measured for natural gas liquids (NGLs). Therefore, a correlation for the vapour pressure of NGLs based upon normally measured properties is required, and API MPMS Chapter 11.2.5-2007/GPA Technical Publication TP-15[19] can be used for this purpose. The procedure given in API MPMS Chapter 11.2.5/GPA TP-15 provides a simplified means of estimating equilibrium vapour pressures of various NGLs from a knowledge of the fluid’s relative density (60 °F/60 °F) and process temperature. The intended application of this procedure is to provide the values of Pe (equilibrium vapour pressure) required to determine the pressure effect contributions to volume correction factors as specified.
See Annex C for titles of petroleum measurement tables given in the 1980 editions of the API, ASTM, and IP volume correction factor standards, as well as a list of the documents that have superseded these documents.ISO 91 pdf download.

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