Wobbe index engineering An indicator of the quality of a fuel gas, measured from the heat produced by burning through a defined orifice in standard temperature and pressure conditions, quantitatively defined as the ratio of Btu's per cubic foot to the square root of the specific gravity of the gas. Traditional ‘town gas’, which is mostly carbon monoxide (CO), typically has an index in the range 701 to 760 and is given the classification label G4; inferior forms can be much lower, with G number G5 for 641 to 700, G6 for 591 to 640, G7 for 531 to 590, and G8 below that.
Natural gas, which is mostly methane (CH4) at the well and almost entirely methane after refining for public use, typically has an index of 1 300 or more. Most bills for gas involve a heat-value factor to correct for variations in quality; measured centrally to represent average quality fed into the distribution network, this is applied to the measured volume consumed by each customer to establish the energy charge. The factor could be the Wobbe index, but may be in common energy units or the ratio of current heat–energy content to the reference value used in setting the tariff.
How to cite this entry:
"Wobbe index" A Dictionary of Weights, Measures, and Units. Ed. Donald Fenna. Oxford University Press, 2002. Oxford Reference Online. Oxford University Press. 14 November 2011
How to cite this entry:
"Wobbe index" A Dictionary of Weights, Measures, and Units. Ed. Donald Fenna. Oxford University Press, 2002. Oxford Reference Online. Oxford University Press. 14 November 2011
