Significance and Use
5.1 The expanded limits of the Adjunct for VCF are defined in a mixture of terms of customary and metric units. shows the defining limits and their associated units in bold italics. Also shown in are the limits converted to their equivalent units (and, in the case of the densities, other base temperatures).
5.2 Note that only the precision levels of the defining values shown in are correct. The other values showing converted units have been rounded to the significant digits shown; as rounded values, they may numerically fall just outside of the actual limits established by the defining values.
5.3 provides a cross-reference between the historical table designations and the corresponding section in the Adjunct for VCF. Note that procedure paragraphs 126.96.36.199 (U.S. customary units) and 188.8.131.52 (metric units) provide methods for correcting on-line density measurements from live conditions to base conditions and then to compute CTPL factors for continuous volume corrections to base conditions.
5.4 When a glass hydrometer is used to measure the density of a liquid, special corrections must be made to account for the thermal expansion of the glass when the temperature is different from that at which the hydrometer was calibrated. The 1980 CTL Tables had generalized equations to correct glass hydrometer readings, and these corrections were part of the printed odd-numbered tables. However, detailed procedures to correct a glass hydrometer reading are beyond the scope of the Adjunct for VCF. The user should refer to the appropriate sections of API MPMS Chapter 9 or other appropriate density/hydrometer standards for guidance.
5.5 The set of correlations given in the Adjunct for VCF is intended for use with petroleum fluids comprising either crude oils, refined products, or lubricating oils that are single-phase liquids under normal operating conditions. The liquid classifications listed here are typical terms used in the industry, but local nomenclature may vary. The list is illustrative and is not meant to be all-inclusive.
5.6 Crude Oils—A crude oil is considered to conform to the commodity group Generalized Crude Oils if its density falls in the range between approximately –10°API to 100°API. Crude oils that have been stabilized for transportation or storage purposes and whose API gravities lie within that range are considered to be part of the Crude Oil group. Also, aviation Jet B (JP-4) is best represented by the Crude Oil correlation.
5.7 Refined Products—A refined product is considered to conform to the commodity group of Generalized Refined Products if the fluid falls within one of the refined product groups. Note the product descriptors are generalizations. The commercial specification ranges of some products may place their densities partly within an adjacent class (for example, a low-density diesel may lie in the jet fuel class). In such cases, the product should be allocated to the class appropriate to its density, not its descriptor. The groups are defined as follows:
5.7.1 Gasoline—Motor gasoline and unfinished gasoline blending stock with a base density range between approximately 50°API and 85°API. This group includes substances with the commercial identification of: premium gasoline, unleaded gasoline, motor spirit, clear gasoline, low-lead gas, motor gasoline, catalyst gas, alkylate, catalytic cracked gasoline, naphtha, reformulated gasoline, and aviation gasoline.
5.7.2 Jet Fuels—Jet fuels, kerosene, and Stoddard solvents with a base density range between approximately 37°API and 50°API. This group includes substances with the commercial identification of: aviation kerosene K1 and K2, aviation Jet A and A-1, kerosene, Stoddard solvent, JP-5, and JP-8.
5.7.3 Fuel Oils—Diesel oils, heating oils, and fuel oils with a base density range between approximately –10°API and 37°API. This group includes substances with the commercial identification of: No. 6 fuel oil, fuel oil PA, low-sulfur fuel oil, LT (low temperature) fuel oil, fuel oil, fuel oils LLS (light low sulfur), No. 2 furnace oil, furnace oil, auto diesel, gas oil, No. 2 burner fuel, diesel fuel, heating oil, and premium diesel.
5.8 Lubricating Oils—A lubricating oil is considered to conform to the commodity group Generalized Lubricating Oils if it is a base stock derived from crude oil fractions by distillation or asphalt precipitation. For the purpose of the Adjunct for VCF, lubricating oils have initial boiling points greater than 700 °F (370 °C) and densities in the range between approximately –10°API to 45°API.
5.9 Special Applications—Liquids that are assigned the special applications category are generally relatively pure products or homogeneous mixtures with stable (unchanging) chemical composition that are derived from petroleum (or are petroleum-based with minor proportions of other constituents) and have been tested to establish a specific thermal expansion factor for the particular fluid. These tables should be considered for use when:
5.9.1 The generalized commodity groups' parameters are suspected of not adequately representing the thermal expansion properties of the liquid.
5.9.2 A precise thermal expansion coefficient can be determined by experiment. A minimum of ten temperature/density data points is recommended to use this method. See 184.108.40.206 of the Adjunct for VCF for the procedure to calculate the thermal expansion coefficient from measured density data.
5.9.3 Buyer and seller agree that, for their purpose, a greater degree of equity can be obtained using factors specifically measured for the liquid involved in the transaction.
5.10 Refer to paragraphs 220.127.116.11 and 18.104.22.168 in the Adjunct for VCF for a complete description of the suitability of the implementation procedures for specific hydrocarbon liquids.
1.1 This guide provides information related to the algorithm and implementation procedure but does not contain the full set of algorithms. The algorithms, instructions, procedures, and examples are located in the associated supplementary adjuncts. The Adjunct for Volume Correction Factors (VCF) for temperature and pressure volume correction factors for generalized crude oils, refined products, and lubricating oils provides the algorithm and implementation procedure for the correction of temperature and pressure effects on density and volume of liquid hydrocarbons. Natural gas liquids (NGLs) and liquefied petroleum gases (LPGs) are excluded from consideration in this standard but may be found in API MPMS Chapter 11.2.4/GPA 8217 Temperature Correction for NGL and LPG. As this Adjunct for VCF will be applied to a variety of applications, the output parameters of CTL, Fp, CPL, and CTPL may be used as specified in other standards.
1.2 Including the pressure correction in the Adjunct for VCF represents an important change from the “temperature only” correction factors given in the 1980 Petroleum Measurement Tables. However, if the pressure is one atmosphere (the standard pressure), then there is no pressure correction and the standard/adjunct(s) will give CTL values consistent with the 1980 Petroleum Measurement Tables.
1.3 The Adjunct for VCF covers 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). Two sets of procedures are included 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).
Note 1: In contrast to the 1980 Petroleum Measurement 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 metric procedures now incorporate the base temperature of 20 °C in addition to 15 °C.
1.4 The procedures in the Adjunct for VCF recognize three distinct commodity groups: crude oil, refined products, and lubricating oils. A procedure is also provided for determining volume correction for special applications where the generalized commodity groups’ parameters may not adequately represent the thermal expansion properties of the liquid and a precise thermal expansion coefficient has been determined by experiment. Procedures for determining Volume Correction Factors (VCF) for Denatured Ethanol can be found in API MPMS Chapter 11.3.3, Miscellaneous Hydrocarbon Properties—Denatured Ethanol Density and Volume Correction Factors, 3rd edition. Procedures for determining Volume Correction Factors (VCF) for Gasoline and Denatured Ethanol Blends can be found in API MPMS Chapter 11.3.4, Miscellaneous Hydrocarbon Properties—Denatured Ethanol and Gasoline Component Blend Densities and Volume Correction Factors, 1st edition.
1.5 The values stated in either SI units or inch‐pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.