API MPMS 11.1
Manual of Petroleum Measurement Standards Chapter 11—Physical Properties Data Section 1—Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils
|Publication Date:||1 May 2004|
This Standard provides the algorithm and implementation procedure for the correction of temperature and pressure effects on density and volume of liquid hydrocarbons which fall within the categories of crude oil, refined products, or lubricating oils; NGLs and LPGs are excluded from consideration in this Standard. The combination of density and volume correction factors for both temperature and pressure is collectively referred to in this Standard as a Correction for Temperature and Pressure of a Liquid (CTPL). The temperature portion of this correction is termed the Correction for the effect of Temperature on Liquid (CTL), also historically known as VCF (Volume Correction Factor). The pressure portion is termed the Correction for the effect of Pressure on Liquid (CPL). As this Standard will be applied to a variety of applications the output parameters specified in this Standard (CTL, Fp, CPL, and CTPL) may be used as specified in other API Manual of Petroleum Measurement Standards (MPMS) Chapters.
Including the pressure correction in this Standard represents an important change from the "temperature only" 1980 Tables. However, if the pressure is one atmosphere (the standard pressure) then there is no pressure correction and this Standard will give CTL values consistent with the 1980 Tables.
This Standard provides general procedures for the conversion of input data to generate CTL, Fp, CPL, and CTPL values at the user specified base temperature and pressure (Tb, Pb). This section is then followed by two sets of procedures for computing volume correction factor, one set for data expressed in customary units (temperature in °F, pressure in psig), the other for the metric system of units (temperature in °C, pressure in kPa or bar). In contrast to the 1980 Tables, the metric procedures require the procedure for customary units be used first to compute density at 60°F. This value is then further corrected to give the metric output.
The procedure recognizes three distinct commodity groups: crude oil, refined products, and lubricating oils. A special application category is also provided which provides volume correction based on the input of an experimentally derived coefficient of thermal expansion.
The purpose of the Petroleum Measurement Tables is to establish a standard set of temperature and pressure related corrections to volume and density based on documented test data. The procedures explained within are designed to allow users to program computer equipment to produce correction factors consistent with those produced by other users employing different computer equipment, yet following the same programming procedure.