Overview REFPROP (Reference Fluid Thermodynamic and Transport Properties) is an industry-standard software developed by the National Institute of Standards and Technology (NIST). Version 9.1 is a legacy release that provides accurate thermophysical property data for a wide range of fluids and mixtures. Because Version 9.1 is older than the current Windows operating systems, the installation process requires specific attention to file directories and administrative privileges to function correctly. Mature+big+tits+gallery+high+quality