Patent ID: 7193189

Claim:
A heat treating system comprising a heat treating furnace, an atmosphere source for supplying a preselected gas atmosphere to the furnace, a heat source to maintain the preselected gas atmosphere inside the furnace at a preselected temperature not greater than a temperature at which wustite (FeO) forms, an oxygen sensor located in situ in the furnace in contact with the preselected gas atmosphere, the oxygen sensor providing a first electrical input that varies according to oxygen content of the preselected atmosphere, a temperature sensor located in situ in the furnace in contact with the preselected gas atmosphere, the temperature sensor providing a second electrical input that varies according to temperature of the preselected atmosphere, and a processor to generate a computed ratio of gaseous hydrogen H 2 (g) to water vapor H 2 O (g) for the preselected atmosphere as a function of the first and second electrical inputs.