NIST 23 contains revised data in a Windows version of the database, including 105 pure fluids and allowing mixtures of up to 20 components. The fluids include the environmentally acceptable HFCs, traditional HFCs and CFCs and 'natural' refrigerants like ammonia. Version9.1 REFPROP 9.1 has replaced the NIST 12 and 14 databases Source code: The FORTRAN subroutines and associated fluid data files are provided for those wishing to access REFPROP calculations from their own applications. Excel spreadsheets: A sample spreadsheet is included that demonstrates how the REFPROP DLL can be linked to Excel. Most properties that are available in the graphical interface can also be calculated in the spreadsheet. System Requirements: PC running Windows 98, 2000, XP, Vista, Window 7 or similar operating system; 10.0 MB available hard disk space.