For superheated-steam expansions, charts show the reheat factors plotted against the ratio of P1/P2 up to a maximum value of 50 for this ratio. The probabilities are that these values of reheat factor are accurate to within one part in a thousand.
The effect of stage efficiency is considered and results presented. Within the superheat region all stage efficiencies are considered to be constant.
Wet-region values are worked out by the step-by-step method, and are presented entirely separate from those for the superheat region. Here also the effect of stage efficiency is included, as well as the effect of decreasing stage efficiency due to increasing moisture content in the expanding steam. The lack of uniformity in practice on this latter issue is pointed out and a suggestion made which should lead to clearer understanding. Moisture removal, which is prevalent in modern turbines, causes discontinuity in the condition curve, and a suggestion is made for the construction of the curve for such a case.
Finally, there is given a method of calculating a condition curve for an expansion from any point in the superheat region and terminating in the wet region. It was found impractical to present a chart of reheat factors for such expansions.