Steam Table Calculator — Saturated & Superheated Steam (IAPWS-IF97)

• Lookup modes. Saturated by temperature or by pressure returns the two-phase boundary — the saturated liquid (f) and saturated vapour (g) states that coexist at that point — from the triple point to the critical point (373.946 °C, 22.064 MPa). Superheated takes a temperature and a pressure and requires the temperature to be above saturation at that pressure; below it the state is compressed liquid.
• Pressure basis. All pressures here are absolute. Gauge readings need atmospheric pressure added (1.013 bar at sea level): 10 bar(g) ≈ 11.0 bar(a), whose saturation temperature is 184 °C, not 180 °C.
• f, g and fg. Subscript f is the saturated liquid, g the saturated vapour, and fg the difference between them — h_fg is the latent heat of vaporisation, the energy to evaporate 1 kg at constant pressure; s_fg the corresponding entropy change.
• Specific volume v and density ρ. Volume per kilogram (m³/kg) and its reciprocal (kg/m³). v_g falls steeply with pressure — 1.67 m³/kg at atmospheric, 0.19 m³/kg at 10 bar(a) — which is what sizes steam mains and safety valves.
• Internal energy u and enthalpy h. h = u + p·v. Enthalpy is the quantity used in flow processes (boilers, turbines, heat exchangers, flash and condensate calculations); internal energy applies to closed, constant-volume systems.
• Entropy s. Used for isentropic (ideal) expansion: a turbine or nozzle is first solved at constant s, then an isentropic efficiency is applied. s_g falls with pressure while s_f rises (the latent-heat contribution s_fg shrinks), so an expansion from saturated vapour at high pressure ends wet.
• Specific heat c_p. Heat per kilogram per kelvin at constant pressure. It rises sharply approaching the critical point and along the saturation line, so a single “c_p of steam” is only useful well into the superheat region.
• Reference state. u and s are zero for saturated liquid at the triple point (0.01 °C, 611.657 Pa), the IAPWS convention shared by conventional steam tables — so enthalpies here compare directly with printed tables and with the NIST WebBook.

• IAPWS-IF97 industrial formulation, Regions 1 (compressed liquid), 2 (superheated vapour) and 4 (saturation line), with the standard's own backward equation for T_sat(p). It is the formulation steam-power and process codes specify; it agrees with the scientific IAPWS-95 formulation to within its stated tolerances (typically better than 0.1 %).
• Region 3, the dense fluid between about 350 °C and the critical point at pressures above 16.5 MPa, and Region 5 (above 800 °C) are not implemented. A superheated lookup that lands in Region 3 returns no result; saturated values between 350 °C and the critical point extend the Region 1 and 2 equations beyond their nominal boundary and drift from the standard by a few percent close to the critical point — treat that end of the table as indicative.
• Ranges: saturated 0–373.946 °C (611.7 Pa – 22.064 MPa); superheated 0–800 °C and up to 100 MPa; compressed liquid to 350 °C. Outside these the calculator returns nothing rather than an extrapolation.
• Single-phase or saturated states only. Wet steam with a dryness fraction x is not looked up directly — combine the f and g values as h = h_f + x·h_fg (and likewise for v, u, s).
• Thermodynamic properties only. Viscosity and thermal conductivity come from separate IAPWS releases (2008 and 2011) and are not on this page; the flow solver carries its own steam viscosity.
• Pure water. Boiler water with treatment chemicals or dissolved solids departs slightly from these values, mainly in boiling point elevation.

The SimuPipe solver uses the same IAPWS-IF97 property set when it routes steam through a network (density, enthalpy and saturation checks, with the single-phase violation flagged as a warning). Its accuracy is documented case by case on the validation page, and the full equation set is in the calculation methodology.

Formulation and comparison sources:

• IAPWS R7-97(2012). Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam. iapws.org — the equations implemented here, including the verification tables reproduced above.
• Wagner, W., Cooper, J. R., Dittmann, A., et al. (2000). "The IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam." Journal of Engineering for Gas Turbines and Power, 122(1), 150–184. doi:10.1115/1.483186 — the peer-reviewed description of IF97, its region structure and accuracy.
• Wagner, W. and Pruß, A. (2002). "The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use." Journal of Physical and Chemical Reference Data, 31(2), 387–535. doi:10.1063/1.1461829 — the scientific formulation IF97 is fitted to; the basis of the NIST tables.
• NIST Chemistry WebBook, SRD 69 — Thermophysical Properties of Fluid Systems. webbook.nist.gov — independent property values for spot checks (IAPWS-95 based).
• Wagner, W. and Kretzschmar, H.-J. (2008). International Steam Tables — Properties of Water and Steam Based on the Industrial Formulation IAPWS-IF97, 2nd ed., Springer. doi:10.1007/978-3-540-74234-0 — printed IF97 tables and charts with the full equation set and backward functions.