# SteamTab *Duo*™ Technical Information

SteamTab *Duo*, designed as an add-in package to popular spreadsheet applications, allows users the convenient access, without leaving the spreadsheet computation environment, to a variety of steam property values. SteamTab *Duo* contains a comprehensive set of thermodynamic and transport properties applicable over a wide range of conditions, with selected derivative and dimensionless properties.

SteamTab *Duo* uses fundamental equations to calculate all steam properties with no interpolation or curve fits to raw steam data. With SteamTab Duo, users have a choice of basing their steam property calculations from either the scientific formulation, or the industrial formulation. The formulations used in SteamTab Duo and their references are shown in the following table.

**Formulations** | **Description** |

**Scientific Formulation** (IAPWS-95) | The scientific formulation is described in the following reference: *Release on the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use*, The International Association for the Properties of Water and Steam, Frederica, Denmark, Sept. 1996.
The scientific formulation is valid in the entire stable fluid region of water from the melting pressure curve starting at 251.165 K to 1273 K at pressures up to 1,000 MPa. The formulation can also be extrapolated to pressures up to about 100 GPa and temperatures up to 5000 K.
SteamTab Duo imposes the following temperature and pressure restrictions:
`Pressure (P, bar): 0 <= P <= 100,000` Temperature (T, K): 190 <= T <= 5000 |

**Industrial Formulation** (IAPWS-IF97) | The industrial formulation is described in the following reference: *Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam*, The International Association for the Properties of Water and Steam, Erlangen, Germany, 1997.
This formulation has the following range of applicability:
`Pressure (P, bar): 0 <= P <= 1,000` Temperature (T, K): 273.15 <= T <= 1,073.15 (for P <= 1,000)
1073.15 <= T <= 2,273.17 (for P <= 100) |

**Note**: SteamTab does not include properties for ice.