DIN EN ISO 18125:2017-08

This International Standard specifies a method for the determination of the gross calorific value of a solid biofuelat constant volume and at the reference temperature 25 °C in a bomb calorimeter calibrated by combustion ofcertified benzoic acid.The result obtained is the gross calorific value of the analysis sample at constant volume with all the water ofthe combustion products as liquid water. In practice, biofuels are burned at constant (atmospheric) pressureand the water is either not condensed (removed as vapour with the flue gases) or condensed. Under bothconditions, the operative heat of combustion to be used is the net calorific value of the fuel at constantpressure. The net calorific value at constant volume may also be used; formulas are given for calculating bothvalues.