Gas quality

• Heating value – the amount of heat released upon the combustion of 1 kg of liquefied or solid fuel or 1 m³ of gas fuel (source, Dictionary of chemical explanatory terms).
• Inferior calorific value - the amount of heat which would be released by the complete combustion in air of a specified quantity of gas, in such way that pressure at which reaction  takes place remains constant, and  all the  products of combustion are returned to the same specified temperature  as that of the reactants, all these products being in the gaseous state (source, LST EN ISO 6976:2004).
• Superior calorific value -the amount of heat which would be released by the complete combustion in air of a specified quantity of gas, in such way that the pressure at which reaction takes place remains constant, and all the products of combustion are returned to the same specified temperature as that of the reactants, all these products being in the gaseous state except for  water formed by combustion,   which is condensed  to the liquid state (source, LST EN ISO 6976:2004).
• Wobbe index - The Wobbe index is a measure of the heat input to gas appliances, derived from the orifice flow equation. It is defined as the specific calorific value, always on the volume basis, divided by the square root of the corresponding relative density.  The heat inputs for different natural gas composition is the same if they have the same Wobbe index and are used under the same gas pressure (source, LST EN ISO 13686:2005).

Hourly data is provided if only there is a physical flow of  natural gas from Latvia to Lithuania or from Lithuania to Latvia.

• For recalculation the superior  calorific value and the Wobbe index values from standard reference conditions when the measurement temperature is +20 °C, burning temperature is +25 °C and the pressure is 101.325 kPa to the standard reference conditions when the measurement temperature is 0 °C, burning temperature is +25 °C and the pressure is 101.325 kPa, applying a constant conversion factor for calorific values 1.0738, for Wobbe index 1.0736 (LST EN ISO 13443).
• For recalculation the gas volume from standard reference conditions when the measurement temperature is +20 °C and the pressure is 101.325 kPa to the standard reference conditions when the measurement temperature is 0 °C and the pressure is 101.325 kPa, applying a constant conversion factor – 0.9313 (LST EN ISO 13443).