PhaseGauge

Thermodynamic diagram · T–s

Temperature–Entropy Diagram

The saturation dome and selected isobars on temperature and specific-entropy axes.

Temperature–entropy diagramSaturation boundary generated from IAPWS-IF97, with selected constant-pressure lines.
Use Plot on a calculator result to place that state on this diagram. Isobars: 0.1 bar, 1 bar, 10 bar, 50 bar, 100 bar, 200 bar, 300 bar, 500 bar.

How to read it

The teal boundary comes from direct saturation calculations. Its liquid and vapor sides meet at the critical point. Inside the dome, equilibrium liquid and vapor coexist and vapor quality is needed to locate a state. Outside it, the state is single phase. Constant-pressure lines are reference guides, not interpolation tables.

Displayed range

The axes cover common water and steam work rather than every extreme allowed by IF97. A valid calculator result outside the plotted range is reported below the figure instead of being clamped to an edge. Diagram paths use one-decimal SVG coordinates; calculations and exported numbers retain their full stored precision.

Generated with iapws-if97@2.2.0. Methodology and verification.