Steam Saturation Properties Table

IAPWS-IF97 Reference Data from 0 °C to 370 °C


Temperature (°C) Sat. Pressure (bar abs) Vapor Density (kg/m³) Liquid Density (kg/m³) Vapor Viscosity (cP) Heat Capacity Ratio (-) Latent Heat (kJ/kg)
Temperature (°C) Sat. Pressure (bar abs) Vapor Density (kg/m³) Liquid Density (kg/m³) Vapor Viscosity (cP) Heat Capacity Ratio (-) Latent Heat (kJ/kg)

Information and Definitions

Steam Saturation Properties

Steam saturation properties describe the thermodynamic state of water at the boundary between the liquid and vapor phases. At a given temperature, the saturation pressure is the pressure at which liquid water and steam coexist in equilibrium. This table provides reference data along the full saturation curve from 0 °C to 370 °C, based on the internationally recognized IAPWS-IF97 formulation.

Saturation Pressure

The saturation pressure (p_sat) is the equilibrium vapor pressure of water at a given temperature. Below this pressure, water exists as steam; above it, as liquid. Saturation pressure increases rapidly with temperature — from 0.006 bar at 0 °C to over 210 bar at 370 °C. It governs the design of steam boilers, condensers, steam traps, and safety relief valves.

Vapor Density (rho_g)

The density of saturated steam increases significantly with temperature and pressure. At 100 °C (atmospheric pressure) it is approximately 0.60 kg/m³, rising to over 200 kg/m³ near the critical point (374 °C). Accurate vapor density is essential for flow calculations through steam lines, orifice plates, and control valves.

Liquid Density (rho_f)

The density of saturated liquid water decreases as temperature rises, from approximately 999.8 kg/m³ at 0 °C to around 451 kg/m³ at 370 °C. Liquid density affects the sizing of steam traps, level measurement systems, and condensate return lines.

Vapor Dynamic Viscosity (mu_g)

The dynamic viscosity of saturated steam is reported in centipoise (cP), equivalent to mPa·s. Like other gases, steam viscosity increases with temperature. It is used in Reynolds number calculations for steam piping, heat exchanger design, and flow metering corrections.

Heat Capacity Ratio (kappa_g)

The heat capacity ratio kappa (Cp/Cv) of saturated steam decreases from approximately 1.33 near 0 °C to values below 1 near the critical point. This ratio governs the compressibility correction factor (Y) in flow calculations and is critical for sizing restriction orifices and control valves for steam service.

Latent Heat of Vaporization (h_fg)

The latent heat (h_fg) is the energy required to convert one kilogram of saturated liquid into saturated vapor at constant pressure. It decreases from about 2501 kJ/kg at 0 °C to zero at the critical point. Latent heat is fundamental for steam heating systems, condensate load calculations, and energy balance in heat exchangers.

IAPWS-IF97 Standard

All data in this table is derived from the International Association for the Properties of Water and Steam Industrial Formulation 1997 (IAPWS-IF97). This is the globally accepted standard for water and steam thermodynamic properties, used in power plant design, boiler engineering, and industrial process simulation worldwide.

The Saturation Curve and Critical Point

The saturation curve ends at the critical point of water: 374.14 °C and 220.9 bar. Above both the critical temperature and pressure, water exists as a supercritical fluid — no distinct liquid or vapor phase remains. Near the critical point, the difference between liquid and vapor densities approaches zero, and many physical properties change rapidly.

Applications in Engineering

Steam saturation data is used for:

  • Steam system design: Boiler sizing, pipe pressure ratings, and steam trap selection
  • Flow metering: Orifice plate and control valve sizing for steam services
  • Heat exchangers: Shell-and-tube condensers, reboilers, and steam heaters
  • Safety systems: Relief valve sizing and blowdown calculations
  • Energy balances: Calculating heat duty and condensate loads
  • Leak rate estimation: Two-phase (wet steam) discharge calculations using HEM density

Wet Steam and Quality

When liquid and vapor coexist, the steam quality x (0 = saturated liquid, 1 = dry saturated steam) defines the phase mixture. The Homogeneous Equilibrium Model (HEM) density of wet steam is computed as:

rho_mix = 1 / (x / rho_g + (1 - x) / rho_f)

This is the formula used in the Leak Rate Calculator on this site for steam service.

Interpolation

For temperatures between table entries, linear interpolation provides acceptable accuracy for most engineering purposes. For high-accuracy work (especially near the critical point), consult IAPWS-IF97 directly or use dedicated software such as REFPROP or XSteam.

References for Steam Saturation Properties

1 International Association for the Properties of Water and Steam (IAPWS) — IF97 Industrial Formulation (1997). The primary standard for water and steam thermodynamic properties used in power and process engineering. https://www.iapws.org/

2 Wagner, W. & Kruse, A. (1998) "Properties of Water and Steam" — Springer-Verlag. Comprehensive textbook presenting the IAPWS-IF97 formulation with application examples for power plant engineering.

3 National Institute of Standards and Technology (NIST) — NIST Chemistry WebBook, Thermophysical Properties of Fluid Systems. Provides independently verified steam property data. https://webbook.nist.gov/

4 Çengel, Y.A. & Boles, M.A. (2018) "Thermodynamics: An Engineering Approach" (9th Edition) — McGraw-Hill. Standard engineering thermodynamics textbook including steam tables based on IAPWS-IF97.

5 Smith, J.M., Van Ness, H.C. & Abbott, M.M. (2005) "Introduction to Chemical Engineering Thermodynamics" (7th Edition) — McGraw-Hill. Chemical engineering reference containing steam saturation data and thermodynamic analysis methods.

6 Perry's Chemical Engineers' Handbook (10th Edition) — McGraw-Hill. Contains steam property tables and correlations for process engineering design.

7 ASHRAE Handbook — Fundamentals (2021). Provides steam and water properties relevant to HVAC and building services engineering.

8 Moran, M.J. & Shapiro, H.N. (2010) "Fundamentals of Engineering Thermodynamics" (7th Edition) — Wiley. Widely used mechanical engineering thermodynamics text with full steam saturation tables.

9 International Steam Tables — IAPWS-IF97, 2nd Edition (2008) — Springer. Updated version of the IAPWS-IF97 standard publication including corrections and Region 5 extensions.

10 Bain, R.W. (1964) "Steam Tables" — HMSO, Edinburgh. Classic British steam table reference, predecessor to modern IAPWS standards.

Related Resources and Calculators

1 Leak Rate Calculator - Calculate leak flow rates for gas, liquid, and steam (wet steam) services. Uses HEM density from this saturation table for steam quality inputs.

2 Absolute Viscosity of Common Gases Table - Reference table for dynamic viscosity of common gases at temperatures from 0 °C to 600 °C.

3 Density of Common Liquids Table - Reference table for liquid density at various temperatures, essential for liquid-phase flow calculations.

4 Molecular Weight of Common Gases Table - Molar mass data for common gases, used in ideal gas law calculations and compressor sizing.

5 Heat Capacity Ratio Table - Reference data for heat capacity ratios (gamma/kappa) for common gases, needed in orifice and valve sizing.

6 Restriction Orifice Flow Calculator - Calculate mass flow through a restriction orifice — applicable to steam services using saturation properties.

7 Orifice Plate Flow Calculator - Size orifice plates for flow measurement including steam applications.

8 Pressure and Temperature Compensation Formula - Learn how temperature and pressure affect fluid properties including steam density and viscosity.

Frequently Asked Questions

Q1 What is the saturation pressure of steam at 100 °C?

A1 At 100 °C the saturation pressure of water is 1.01325 bar (absolute), which is standard atmospheric pressure. This is the well-known boiling point of water at sea level. Steam produced at this condition is called atmospheric steam and has a vapor density of approximately 0.598 kg/m³. It is the reference condition often used for comparing steam properties at higher pressures.

Q2 Why does the density of saturated steam increase so much with temperature?

A2 As temperature rises, the saturation pressure increases rapidly. Higher pressure compresses the steam into a smaller volume, increasing its density. Near the critical point (374 °C, 220.9 bar), the density of saturated steam approaches that of the saturated liquid, and the distinction between liquid and vapor disappears. This behavior is governed by the van der Waals interactions between water molecules and is accurately described by IAPWS-IF97.

Q3 What is wet steam and how is its density calculated?

A3 Wet steam is a mixture of saturated vapor and saturated liquid droplets, characterized by steam quality x (where x = 0 is fully liquid and x = 1 is dry steam). The density of wet steam is calculated using the Homogeneous Equilibrium Model (HEM): rho_mix = 1 / (x / rho_g + (1 - x) / rho_f). Even a small liquid fraction dramatically reduces the average density. For example, at 250 °C with x = 0.01, the mixture density is approximately 575 kg/m³ — close to the liquid density—because the liquid phase dominates the volume.

Q4 What is the IAPWS-IF97 standard and why should I trust this data?

A4 IAPWS-IF97 (International Association for the Properties of Water and Steam, Industrial Formulation 1997) is the internationally accepted standard for the thermodynamic properties of water and steam. It is used worldwide by power plant operators, boiler manufacturers, and process engineers. The formulation was developed from hundreds of experimental measurements and is implemented in major simulation tools including REFPROP, ASPEN, and XSteam. Data in this table is sourced directly from IAPWS-IF97 Region 4 (the saturation region).

Q5 How does latent heat change with temperature?

A5 Latent heat of vaporization (h_fg) decreases monotonically as temperature increases. At 0 °C it is approximately 2501 kJ/kg; at 100 °C it drops to 2257 kJ/kg; and it reaches zero at the critical point (374 °C). This has practical implications: at higher pressures, less energy is required to vaporize water, but the steam carries less energy per kilogram. Steam heating systems at higher pressures therefore need greater mass flow rates to deliver the same heat duty.

Q6 What is the heat capacity ratio (kappa) and why does it matter for flow calculations?

A6 The heat capacity ratio kappa (Cp/Cv) determines how a gas responds to isentropic compression or expansion. For steam at moderate temperatures it is around 1.31–1.33; it decreases toward unity near the critical point. In flow calculations, kappa appears in the compressibility (expansion) factor Y used for sizing orifice plates and control valves. Using the wrong kappa value can lead to significant errors in flow metering and valve sizing for steam service.

Q7 Can I use this table to size a steam control valve or orifice plate?

A7 Yes, this table provides the key thermodynamic properties needed for steam valve and orifice sizing: saturation pressure, vapor density, vapor viscosity, and heat capacity ratio. For a control valve in saturated steam service, use the vapor density (rho_g) and kappa at the inlet temperature. For wet steam, calculate the HEM density using the quality x. Always verify whether the steam is superheated — this table covers only the saturation curve; superheated steam requires a separate set of steam tables.

Q8 What happens if the steam temperature in my process is above 370 °C?

A8 Above 370 °C the steam is either superheated (if the pressure is below saturation) or supercritical (if both temperature and pressure exceed the critical point). The saturation curve ends at 374.14 °C and 220.9 bar. For superheated steam, use the IAPWS-IF97 Region 2 tables. For supercritical water (above both the critical temperature and pressure), Region 3 applies. This table is not valid beyond 370 °C.