StmEng_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 English units. Use only for wet steam.
Format
StmEng_XPH(P, H)
Arguments
-
P
Pressure of the steam in psia. The valid range is 0.08865 to 3208.2 psia.
-
H
Specific enthalpy of the steam in BTU/lbm. The valid range is -0.017879547 to 1744.60206 BTU/lbm.valid range is -1 to 1860 BTU/lbm.
Returns
Computed steam quality (vapor fraction) or Error digital state.
Sample Values
|
Pressure |
Enthalpy |
Steam Quality |
|
300. |
1122.0 |
0.899 |
|
800. |
1130.4 |
0.900 |
|
1400. |
1117.7 |
0.901 |
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.