4. Significance and Use
4.1 The expanded limits of API MPMS Chapter 11.1-2004/Adjunct to IP 200/04/Adjunct to ASTM D1250-04 (ADJD1250CD) are defined in a mixture of terms of customary and metric units. Table 1 shows the defining limits and their associated units in bold italics. Also shown in Table 1 are the limits converted to their equivalent units (and, in the case of the densities, other base temperatures).
4.2 Note that only the precision levels of the defining values shown in Table 1 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.
4.3 Table 2 provides a cross-reference between the historical table designations and the corresponding section in API MPMS Chapter 11.1-2004/Adjunct to IP 200/04/Adjunct to ASTM D1250-04 (ADJD1250CD). Note that procedure paragraphs 11.1.6.3 (U.S. customary units) and 11.1.7.3 (metric units) provide methods for correcting on-line density measurements from live conditions to base conditions and then to compute VCF factors for continuous volume corrections to base conditions.
4.4 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 API MPMS Chapter 11.1-2004/Adjunct to IP 200/04/Adjunct to ASTM D1250-04 (ADJD1250CD). The user should refer to the appropriate sections of API MPMS Chapter 9 or other appropriate density/hydrometer standards for guidance.
4.5 The set of correlations given in API MPMS Chapter 11.1-2004/Adjunct to IP 200/04/Adjunct to ASTM D1250-04 (ADJD1250CD) 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.
4.6 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.
4.7 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:
4.7.1 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.
4.7.2 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.
4.7.3 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.
4.8 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 API MPMS Chapter 11.1-2004/Adjunct to IP 200/04/Adjunct to ASTM D1250-04 (ADJD1250CD), lubricating oils have initial boiling points greater than 700°F (370°C) and densities in the range between approximately -10°API to 45°API.
4.9 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:
4.9.1 The generalized commodity groups' parameters are suspected of not adequately representing the thermal expansion properties of the liquid.
4.9.2 A precise thermal expansion coefficient can be determined by experiment. A minimum of 10 temperature/density data points is recommended to use this method. See 11.1.5.2 of API MPMS Chapter 11.1-2004/Adjunct to IP 200/04/Adjunct to ASTM D1250-04 (ADJD1250CD) for the procedure to calculate the thermal expansion coefficient from measured density data.
4.9.3 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.
4.9.4 Specific Examples:
4.10 Refer to paragraphs 11.1.2.4 and 11.1.2.5 in API MPMS Chapter 11.1-2004/Adjunct to IP 200/04/Adjunct to ASTM D1250-04 (ADJD1250CD) for a complete description of the suitability of the implementation procedures for specific hydrocarbon liquids.