API MPMS 11.2.4 ERTA:2011

The actual Standard represented by this report consists of the explicit implementation procedures. Sample tables, flow charts, and specific examples created from a computerized version of these implementation procedures are presented within. The examples are to provide guides and check points to those who wish to implement a computerized procedure to represent the Standard, however these are not a part of the actual Standard. This Standard covers a 60 °C relative density range of 0.3500 to 0.6880 which nominally equates to a density at 15 °C of 351.7 to 687.8 kg/m3 and a density at 20 °C of 331.7 to 683.6 kg/m3. The temperature range of this Standard is -50.8 to 199.4 °C ( -46 to 93 °C). At all conditions, the pressure is assumed to be at saturation conditions (also known as bubble point or saturation vapor pressure). The calculation method was developed from GPA RR-148 'Volume Correction Factors for Natural Gas Liquids - Phase II'[11] and API/ASTM/GPA Technical Publication, TP-25, September, 1998[10]. The implementation procedures for Tables 23 and 24 are entirely consistent with those presented in TP-25. Supporting data can be found in GPA RR-147 'Density Measurements on Natural Gas Liquids'[12]. GPA RR-133 'Volume Correction Factors for Natural Gas Liquids - Phase I'[13] should no longer be used, as GPA RR-148 completely replaced it. The implementation procedures describe how to: 1) calculate the CTL given an appropriate density factor at the basis temperature and an observed temperature, and 2) calculate the appropriate density factor at basis temperature given a relative density at an observed temperature. The implementation procedures are presented in pairs by base temperature. First the procedures for Tables 23 and 24 at a 60 °C base temperature are given. The procedure for Table 23 makes use of the procedure described in Table 24 thus Table 24 is presented first. These are followed by procedures for Tables 54 and 53 at a base temperature of 15 °C which themselves make use of procedures in described in Tables 23 and 24; these in turn are followed by the procedures for Tables 60 and 59 at a base temperature of 20 °C which also make use of procedures in described in Tables 23 and 24.