List of steam functions for analysis expressions
- Last UpdatedSep 26, 2025
- 2 minute read
- PI System
- PI Server 2024 R2
- PI Server
You can include steam functions in analysis expressions to calculate the thermodynamic properties of steam. These functions are based on the 2007 revision of the IAPWS Industrial Formulation. The implementation is based on the combination of officially published forward and backward equations for all applicable regions.
Note: Avoid confusing these steam functions with a similar set of steam functions used for PI Performance Equations (PE) in tag-based analytics. For PI PE steam functions, see Steam functions (tag-based calculations). For more information on steam functions in asset and tag-based analytics, see Learn about steam functions in asset and tag-based analytics.
The table below lists supported functions and descriptions. Ranges and units of measure for steam function properties are detailed in List of ranges for steam function inputs. Reference states that apply to steam are listed in List of steam property reference states.
Steam function descriptions
|
Function |
Description |
|---|---|
|
Steam_TsatP |
Saturation temperature as a function of pressure. |
|
Steam_HsatP |
Saturation vapor specific enthalpy as a function of pressure. |
|
Steam_SsatP |
Saturation vapor specific entropy as a function of pressure. |
|
Steam_VsatP |
Saturation vapor specific volume as a function of pressure. |
|
Steam_PsatT |
Saturation pressure as a function of temperature. |
|
Steam_HsatT |
Saturation vapor specific enthalpy as a function of temperature. |
|
Steam_SsatT |
Saturation vapor specific entropy as a function of temperature. |
|
Steam_VsatT |
Saturation vapor specific volume as a function of temperature. |
|
Steam_VPT |
Vapor specific volume as a function of pressure and temperature. |
|
Steam_VPTL |
Liquid specific volume as a function of pressure and temperature. (For water.) |
|
Steam_VPH |
Vapor specific volume as a function of pressure and enthalpy. |
|
Steam_VPS |
Vapor specific volume as a function of pressure and entropy. |
|
Steam_HPT |
Vapor specific enthalpy as a function of pressure and temperature. |
|
Steam_HPTL |
Liquid specific enthalpy as a function of pressure and temperature. (For water.) |
|
Steam_HPS |
Vapor specific enthalpy as a function of pressure and entropy. |
|
Steam_SPT |
Vapor specific entropy as a function of pressure and temperature. |
|
Steam_SPTL |
Liquid specific entropy as a function of pressure and temperature. (For water.) |
|
Steam_SPH |
Vapor specific entropy as a function of pressure and enthalpy. |
|
Steam_TPH |
Temperature as a function of enthalpy and pressure. |
|
Steam_TPS |
Temperature as a function of entropy and pressure. |
|
Steam_XPH |
Steam quality (vapor fraction) as a function of pressure and enthalpy. (For wet steam.) |
|
Steam_XPS |
Steam quality (vapor fraction) as a function of entropy and pressure. (For wet steam.) |
|
Steam_VPX |
Steam specific volume as a function of pressure and steam quality. (For wet steam.) |
|
Steam_HPX |
Specific enthalpy as a function of pressure and steam quality. (For wet steam.) |
|
Steam_SPX |
Steam specific entropy as a function of pressure and steam quality. (For wet steam.) |