Steam97 ActiveX DLL

Steam97 ActiveX DLL (32 bit & 64 bit) based on IAPWS-IF97

For Windows 7 / Windows 8 / Windows 8.1 / Windows 10 / Windows 11

Steam Properties ActiveX DLL Library

About Steam 97 ActiveX Dll Library

The Steam97 ActiveX DLL library calculates 30 thermodynamic and transport properties of water and steam, and provides access to 8 constant properties used by the steam tables solver.

The library supports SI and English units.

It allows 16 different combinations of input variables to be used for calculations.

Input variables that can be used are:

  •  1 Pressure
  •  2 Temperature
  •  3 Enthalpy
  •  4 Entropy
  •  5 Volume
  •  6 Internal energy
  •  7 Steam quality

Main features of the library:
  • Thoroughly tested with 100 million points generated by random number generator
  • Based on the international standard formulation
  • Developed in C++ for maximum speed
  • Thread safe
  • 32-bit and 64-bit versions of the library are included
  • Includes high speed and high accuracy calculation modes
  • The libraries can be used in any programming language that supports ActiveX (COM) components
  • Full .NET support (C#, VB.NET)
  • Well designed and easy to use APIs
  • Royalty free
  • Used by thousands of Engineering Professionals from all around the world
  • One year free technical support

Used Formulations

The library uses new industrial formulation for steam tables, called "IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IAPWS-IF97)", and replaces the previous industrial formulation for steam tables, IFC-67.

IAPWS-IF97 improves significantly both accuracy and speed of the calculation of the thermodynamic properties compared with the old formulation.

For transport properties calculations are based on the latest internationally accepted equations also available from IAPWS.

Calculation Mode - NEW

The library provides two calculation modes, one for maximum speed and one for maximum accuracy.

When the library is in the maximum speed mode, the steam calculation engine will internally use backward equations (no iterations) wherever possible, thus making calculation extremely fast.

When the library is set to the maximum accuracy calculation mode, the steam calculation engine will calculate all properties with full iterations. In this calculation mode steam tables solver will calculate results with higher accuracy, but calculations will be slower.

The library provides helper functions to set / get calculation mode dynamically. Calculation mode setting is applied internally to the steam tables solver, so no code changes are required.

To meet your speed and accuracy requirements you can change calculation mode in your code as many times as you want.

Steam Properties

The following termodynamic and transport properties can be calculated with Steam97 ActiveX DLL library:

Calculable properties in SI or E units - Steam97 ActiveX DLL v3.0
  1 Pressure
  2 Temperature
  3 Density
  4 Specific volume
  5 Specific enthalpy
  6 Specific entropy
  7 Specific internal energy
  8 Specific isobaric heat capacity
  9 Specific isochoric heat capacity
 10 Speed of sound
 11 Isentropic exponent
 12 Specific Helmholtz free energy
 13 Specific Gibbs free energy
 14 Compressibility factor
 15 Steam quality
 16 Region
 17 Isobaric volume expansion coefficient
 18 Isothermal compressibility
 19 Partial derivative (dV/dT)p
 20 Partial derivative (dV/dP)T
 21 Partial derivative (dP/dT)v
 22 Partial derivative (dP/dV)T
 23 Isothermal Joule-Thomson coefficient
 24 Joule-Thomson coefficient
 25 Dynamic viscosity
 26 Kinematic viscosity
 27 Thermal conductivity
 28 Thermal diffusivity
 29 Prandtl number
 30 Surface tension
Constants used in calculation in SI or E units
  1 Specific gas constant
  2 Molar gas constant
  3 Molar mass
  4 Critical temperature
  5 Critical pressure
  6 Critical density
  7 Triple-point temperature
  8 Triple-point pressure

Range of Validity

The entire set of equations of the IAPWS-IF97, used by the application for calculation of thermodynamic properties, is defined by the following temperature and pressure range:

  • 273.15 K <= T < = 1073.15 K    p < = 100 MPa
  • 1073.15 K < T < = 2273.15 K    p < = 50 MPa

Steam97 Range of Validity

Fig.1 Steam table regions defined in the IAPWS-IF97


1. Steam97 ActiveX Dll in Object Browser (Visual Studio)

Steam97 ActiveX Dll in Object Browser (Visual Studio)

Fig 1. Steam97 ActiveX Dll in Object Browser (Visual Studio)

2. Steam97 ActiveX Dll in C# code editor

Steam97 ActiveX Dll in c# code editor

Fig 2. Steam97 ActiveX Dll in c# code editor

3. Sample application (in C# and VB.NET) included with the library

Sample application (in c# and VB.NET)

Fig 3. Sample application (in c# and VB.NET)


Steam97 ActiveX DLL demo libraries (32-bit and 64-bit) - version 3.0 are available on request.

If you would like to try the demo, contact us at .


Try the fully functional version of the Steam97 ActiveX DLL library online.

  • Our web site "Steam Tables Online" provides a "Steam Tables Calculator" which is powered by the Steam97 ActiveX DLL.
    It is used by thousands of Engineering Professionals from all around the world.
  • So far, the library has successfully completed 139272 hours of work (that is 15+ years) under heavy load in a multi user environment on the Internet.
    Visit the steam tables web application and try it yourself.

Price info

Prices subject to change without notice!

A license includes 32 bit and 64 bit versions of the library.

Steam97 ActiveX DLL version 3.0
1 licenseUSD 2995.00
2 or 3 licensesUSD 2495.00 per copy
4 or more licensesUSD 1995.00 per copy
Team licenseUSD 11995.00

The Team license is valid for the whole team, regardless of the number of developers.


Each license also includes the following:

  • One year free e-mail technical support
  • One year free minor version updates if available (for example 3.1, 3.x up to, but not including version 4.0)

If you have any questions, please don't hesitate to contact sales. Contact information is provided on the following page:

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General Information

For quick access to the Steam97 ActiveX DLL, you may purchase and download our product using automated and secure online ordering system.
After ordering, you will receive a notification mail with further instructions for how to download and install the software.

The Registration includes a free subscription program. Each Registered user will be receiving bug fixes and technical support for the registered version within one year.

Shipping by the postal mail is not available.

How to order

1. Internet ordering

Available ordering options (open an order form to select):

  • Credit Card (Visa®, Mastercard®, American Express®, Discover®)
  • PayPal
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To buy a specific number of licenses for the Steam97 ActiveX DLL click the button: Open order page for the Steam97 ActiveX DLL.

To purchase a Team License contact sales. Contact information is provided on the following page:
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2. Bank Direct Payment

If you prefer to pay for the product by "Bank Direct Payment", contact sales. Contact information is provided on the following page:

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