C002 – ISO 6976:1989 Calorific Value and Relative Density


This calculates calorific values, density, relative density and Wobbe index from a gas composition. Results are calculated for the composition treated as both a real and an ideal gas, inferior (net) and superior (gross) calorific value and Wobbe index are displayed in each case.


FLOCALC Calculation reference F002

Kelton calculation reference C002

Kelton calculation reference C111

International standard, Natural Gas – Calculation of calorific values, density, relative density and Wobbe index (ISO 6976: 1989)

Hydrocarbon Tail

  • No Tail
  • C6 Tail
  • C7 Tail
  • C9 Tail

Select the appropriate hydrocarbon tail. Where a tail is selected the percentage split of each component is entered, this is generally obtained from laboratory analysis.

Reference Temperature (Combustion/Metering)

  • 25/0
  • 15/0
  • 0/0
  • 15/15
  • 25/20

This option is used to select the reference temperature used for the calculation. There is a choice of various combustion/metering temperatures used around the world.

Molecular Weights

  • Rounded
  • Full Precision

This option gives the choice to use the rounded molecular weights as shown in Table 1, or calculate the molecular weights with full precision using the elemental molars masses shown beneath Table 1.


This performs the calculations from C111 when set for 1989