© 2019 Department of Petroleum Resources. All rights reserved Department of Petroleum Resources (DPR) PROCEDURE GUIDE

Page 96 of 114
 
95 | P a g e 
 
 
 
Mi =  molecular mass of individual LNG components in Kg/kmol rounded to 
3 (three) decimal places and specified in ISO 6976 (1995); 
 
Qr =  quantity of Natural Gas in Megajoules returned to the LNG Tanker during 
the unloading process calculated in accordance with the formula: 
𝑄𝑟  =  V*  
288.15
( 273.15 + T𝑣)   *   P  *  
1
1013.25   *  37.0 
 
 
Where:  the figure of 37.0 represents the gross heating value in MJ/m3(st) of the 
vapour returned to the LNG Tanker at 15C (Fifteen degrees Celsius) and 
1013.25 millibars. The figure 1013.25 represents standard atmospheric 
pressure expressed in millibars. The figures 273.15 and 288.15 represent 
0C and 15C (zero degrees Celsius and fifteen degrees Celsius) 
respectively as expressed in K (Kelvin); 
 
P = average absolute pressure of vapour in the LNG Tanker immediately before 
loading and after unloading, expressed in millibars, rounded to a whole 
millibar 
 
T = average temperature of the LNG in an LNG Tanker before and after loading 
or before unloading, expressed in degrees Celsius rounded to 1 (one) decimal 
place 
 
Tv =  average temperature of the LNG in an LNG Tanker before and after loading 
or before unloading, in degrees Celsius rounded to 1 (one) decimal place 
 
V = the total volume of the liquid cargo loaded or unloaded, in cubic metres 
rounded to 1 (one) cubic metre 
 
Vi =  molar volume of individual LNG components at temperature T, in m3/kmol 
rounded to 6 (six) decimal places, obtained by linear interpolation. 
  
Xi = molar fraction of individual LNG components of sample taken from the 
receiving lines, determined by gas chromatographic analysis as specified in 
Clause 12.4; 
Xm = the value of Xi for methane; and