StmSI_XPH
- Last UpdatedSep 17, 2025
- 1 minute read
- PI System
- PI Server 2023
- PI Server
Calculates the steam quality (vapor fraction) as a function of pressure and enthalpy—all variables expressed in SI units. Use only for wet steam.
Format
StmSI_XPH(P, H)
Arguments
-
P
Pressure of the steam in KPa. The valid range is 0.611213 to 22064 KPa.
-
H
Specific enthalpy of the steam in J/g. The valid range is 0.04158 to 4160.641 J/g.
Returns
Computed steam quality (vapor fraction) or Error digital state.
Sample Values
|
Pressure |
Enthalpy |
Steam Quality |
|
2500. |
2617.0 |
0.9 |
|
5000. |
2630.2 |
0.9 |
|
10000. |
2595.8 |
0.9 |
Note: If the input enthalpy is greater than that of the saturated vapor, the function returns 1.0 as vapor fraction. If the input enthalpy is less than that of the saturated liquid, the function would compute negative vapor fraction without setting an error state.