State number

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The dimensionless number of states describes the ratio of a gas volume in the normal state to the gas volume in the operating state.



  • = Standard volume
  • = Operating volume, d. H. Volume in the operating state
  • = Standard temperature (273.15  Kelvin , corresponds to 0 ° C)
  • = mean operating temperature of the gas in Kelvin (for gas meters without temperature measurement set to 288.15 Kelvin or 15 ° C)
  • = Standard air pressure (1 013.25 hPa or 1 013.25 mbar or 1.01325 bar)
  • = Annual mean value of the air pressure (in Pascal ):
  • = Operating pressure or effective pressure of the gas ( overpressure in Pascal)
  • = Water vapor partial pressure of the gas (in Pascal)
  • = Number of compressibility (dimensionless; at )


The state number is used by gas supply companies to calculate the amount of thermal energy actually extracted in kilowatt hours . The operating volume determined on the gas meter from the meter reading difference is first multiplied by the status number. The standard volume determined in this way is then multiplied by the calorific value:


  • = Amount of energy (in )
  • = Gas volume in operating state (in )
  • = Standard volume, d. H. Gas volume in standard condition (in )
  • = mean calorific value in standard condition (in ).


Calculation of the state number for natural gas customers in Munich, in the district of Thalkirchen-Obersendling-Forstenried-Fürstenried-Solln
with the values:

This gives the state number:


  • Ulrich Wernekinck (Ed.): Gas measurement and gas billing. 3rd edition, Vulkan Verlag, Essen 2005, ISBN 978-3-8027-5617-7 .
  • Knut Håkansson: Lexicon of the gas installation. (Gas installation from A - Z), 2nd edition, Vulkan Verlag, Essen 1996, ISBN 3-8027-2533-6 .

Individual evidence

  1. Procedure for determining the condition number and billing calorific value (PDF; 23 kB) website of SWM Infrastruktur GmbH, accessed on October 6, 2014

Web links