API MPMS Chapter 11.2.5

This revised standard is effective upon the date of publication and supersedes all previous revisions of the standard, including API MPMS 11.2.2A/GPA TP-15.

Two methods used for calculation of the correction factor for pressure effects (F_p) were standardized by API: MPMS Chapter 11.2.1-1984 (now superseded by Chapter 11.1-2004 and MPMS Chapter 11.2.2-1986. These methods require a knowledge of the equilibrium bubble point pressure (vapor pressure) at the measured conditions. However, the vapor pressure of the process liquid is generally not measured. The vapor pressure can also be calculated from compositional information, but the composition is not always measured for natural gas liquids (NGLs). This document provides a simplified correlation for the vapor pressure of NGLs based upon normally measured.