Specification

The NGA Extension is an optional add-on for the Clarity software. It can be ordered as a part of a new software license or as an extension to an existing one (p/n A32).

It provides options for the calculation of gas properties in compliance with the following norms:

Natural Gas

  • ISO 6976-16

    • Calculation of calorific values, density, relative density, and Wobbe index from composition.

  • ISO 6976-95 (outdated; replaced by ISO 6976-16)

    • Calculation of calorific values, density, relative density, and Wobbe index from composition.

  • ASTM D 3588-98

    • The standard practice for calculating heating values, compressibility factor, and relative density of gaseous fuels.

  • GPA 2172-09

    • Calculation of gross/net heating values, relative density, and compressibility factor for natural gas mixtures from compositional analysis.

Liquefied Petroleum Gas

  • ASTM D 2421-02

    • The standard practice for interconversion of analysis of C5 and lighter hydrocarbons to gas-volume, liquid-volume, or weight basis.

  • ASTM D 2598-02

    • The standard practice for calculation of certain physical properties of liquefied petroleum (LP) gases from compositional analysis.

  • ISO 8973-97 / EN 589+A1

    • Standards for calculation methods for density and vapor pressure in liquefied petroleum gases.

Calculated properties according to norms

The particular calculation details and equations used can be found in the chapter "ISO 6976-16".

ISO 6976-16

  • Compression Factor
  • Mean Molecular Weight
  • Relative Density
  • Density
  • Gross Calorific Value
  • Net Calorific Value
  • Gross Wobbe Index
  • Net Wobbe Index

ISO 6976-95 (outdated)

  • Compression Factor
  • Mean Molecular Weight
  • Relative Density
  • Density
  • Superior Calorific Value
  • Inferior Calorific Value
  • Wobbe Index

ASTM D 3588-98 and GPA 2172-09

  • Molar Mass
  • Molar Mass Ratio
  • Compressibility Factor
  • Relative Density
  • Ideal Heating Value (incl.calculations in BTU - British Thermal Units)
  • Real Heating Value (incl.calculations in BTU - British Thermal Units)

ASTM D 2421-02 and ASTM D 2598-02

  • Vapor Pressure
  • Relative Density
  • Motor Octane Number

ISO 8973-97 / EN 589+A1

  • Absolute Vapor Pressure (for Molar and Mass Percent only)
  • Gauge Vapor Pressure (for Molar and Mass Percent only)
  • Octane Number

Additional calculations

  • Methane Number is calculated if the LPG norms are selected (ASTM D 2421-02 and ASTM D 2598-02 or ISO 8973-97 / EN 589+A1). The calculation is based on the calculated (Motor) Octane Number according to KUBESH, John; KING, Steven R.; LISS, William E. Effect of gas composition on octane number of natural gas fuels. SAE Technical Paper, 1992