Calculator
Steam Quality Estimator
Estimate steam dryness fraction using the throttling-calorimeter method — flash wet steam to a low pressure and measure the superheat temperature.
Interactive toolUpdated July 2026
Inputs
hf₁ 781, hfg₁ 1999 kJ/kg
tsat₂ 100°C
Superheat 30.0°C
Results
Dryness Fraction x
0.978
steam quality 97.8%
Steam vs Water
97.8% vapour
x = (h₂ − hf₁) / hfg₁ = (2736 − 781) / 1999
How It Works
x = (h₂ − hf₁) / hfg₁, where h₂ = hg₂ + cp·(T₂ − tsat₂)
Throttling drops the pressure without changing enthalpy. If the steam is wet, the flashing dries it and superheats it at P₂. Measuring the superheat gives h₂, which back-calculates the original dryness. Target process steam x > 0.98; turbine steam > 0.995.