ASTM D1250-08(2013)

4.1 The expanded limits of API 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 CTPL 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 4.5 The set of correlations given in API 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:

4.8 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:

4.10 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.

1.1 The API MPMS Chapter 11.1–2004/Adjunct to IP 200/04/Adjunct to ASTM D1250–04 (ADJD1250CD) 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. The combination of density and volume correction factors for both temperature and pressure is collectively referred to in the standard/adjunct(s) 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/adjunct(s) (CTL, F_p, CPL, and CTPL) may be used as specified in other standards.

1.2 Including the pressure correction in API MPMS Chapter 11.1–2004/Adjunct to IP 200/04/Adjunct to ASTM D1250–04 (ADJD1250CD) 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 API MPMS Chapter 11.1–2004/Adjunct to IP 200/04/Adjunct to ASTM D1250–04 (ADJD1250CD) covers general procedures for the conversion of input data to generate CTL, F_p, CPL, and CTPL values at the user specified base temperature and pressure (T_b, P_b). 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). 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 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.