FieldEngineersKitEngineering Reference & ASME Code Basis
1. Formula & conversion factors
IAPWS-IF97 Industrial Formulation for the Thermodynamic Properties of Water and Steam · ASME Steam Tables (IAPWS-IF97 basis) · ISO 80000-5 (Thermodynamics Quantities)
h = R · T · τ · (γτ0 + γτr) [kJ/kg]
s = R · [τ · (γτ0 + γτr) − (γ0 + γr)] [kJ/(kg·K)]
v = R · T · π · (γπ0 + γπr) / p [m³/kg] · ρ = 1/v
IAPWS-IF97 Region 2 superheated · Region 4 saturation (Tsat, wet steam with quality x)
Steam thermodynamic properties from the IAPWS-IF97 industrial formulation. Saturation mode uses Region 4 Tsat(P) with quality x between liquid (Region 1) and vapor (Region 2). Superheated mode evaluates Region 2 Gibbs free energy at T and P (T ≥ Tsat). Scope ends at Pc = 22.064 MPa.
- h (Specific enthalpy) — Steam enthalpy from Gibbs free energy (kJ/kg or Btu/lb).
- s (Specific entropy) — Steam entropy (kJ/(kg·K) or Btu/(lb·°F)).
- v / ρ (Specific volume / density) — v from π·γ_π; ρ = 1/v.
- Tsat (Saturation temperature) — Region 4 backward Tsat(P) on the saturation line.
- x (Steam quality) — Dryness fraction 0 (sat. liquid) to 1 (sat. vapor).
- hfg (Latent heat) — hg − hf at the saturation pressure.
2. Quick reference lookup table
| Duty | P | State | h | Tsat / ρ | v |
|---|---|---|---|---|---|
| Default | 10 bar | Sat. vapor x=1 | 2777.1 kJ/kg | 179.88 °C | 0.1944 m³/kg |
| pSEO | 20 bar · 300 °C | Superheated R2 | 3024 kJ/kg | 7.97 kg/m³ | 0.1255 m³/kg |
| pSEO | 3 bar | Sat. vapor x=1 | 2724.9 kJ/kg | 133.52 °C | 0.6058 m³/kg |
| pSEO | 15 bar · 250 °C | Superheated R2 | 2924 kJ/kg | 6.58 kg/m³ | 0.1520 m³/kg |
| Imperial | 145 psi | Sat. vapor | ~1194 Btu/lb | ~356 °F | — |
| Imperial | 290 psi · 572 °F | Superheated | ~1300 Btu/lb | ~7.97 kg/m³ | — |
Values from IAPWS-IF97 Region 2 / 4 evaluation in this app. Spec sheet density at 20 bar · 300 °C uses IF97 ρ ≈ 7.97 kg/m³ (not ideal-gas estimates).
3. How to use this calculator
- 1
Select unit system
Use the navbar UnitSwitcher for metric (bar, °C) or imperial (psi, °F).
- 2
Enter absolute pressure
Stay within 0.01–100 bar abs (below critical 22.064 MPa).
- 3
Choose saturation or superheated
Saturation: set dryness x. Superheated: set T ≥ Tsat.
- 4
Read h hero and property rows
Hero shows enthalpy with Tsat (sat.) or density (superheat). Rows list hfg, s, μ, and k.
4. Engineering FAQ
A tool that evaluates steam enthalpy, entropy, density, Tsat, and latent heat from the IAPWS-IF97 industrial formulation used by ASME steam tables.
Use saturation on the two-phase line with quality x. Use superheated when steam temperature is above Tsat at the given absolute pressure (Region 2).
No. Pressures at or above 22.064 MPa are outside Region 2/4 scope — verify with a full ASME steam table.
At Tsat(P): h = hf + x·(hg − hf) (same mixing for s and v).