Process Ace Steam Properties 2.2.0
the author of this app says:
This program calculates thermodynamic and transport properties of steam for pressures between 0.08865 and 2398.45 PSIA (0.0061 and 165.37 Bar) and temperatures between 32.022 and 1472 degrees F (0.01 and 800 degrees C).
The program calculates properties for all regions (superheated steam, saturated steam and subcooled water).
All properties are calclated (no interpolation). Results are very accurate, and will closely match published steam tables.