(Graphical User Interface) to ensure the fluid files and mixture models load correctly. National Institute of Standards and Technology (.gov) 2. Linking to Microsoft Excel

Installing NIST REFPROP 9.1 typically involves the base software installation on Windows followed by linking the Dynamic Link Library (DLL) to applications like Excel, MATLAB, or Python. 1. Core Software Installation (Windows) REFPROP 9.1 is a licensed software provided by NIST. Run the Installer

: If you no longer have your original 9.1 installer and need to reinstall, you can contact NIST support at ian.bell@nist.gov for assistance. National Institute of Standards and Technology (.gov) Are you planning to use REFPROP with a specific application like Excel, MATLAB, or Python? Answers to Frequently Asked Questions - NIST Pages

How to Install REFPROP 9.1: A Complete Step-by-Step Guide REFPROP (Reference Fluid Thermodynamic and Transport Properties), developed by NIST, is the gold standard for scientists and engineers needing accurate properties of industrially important fluids and mixtures. While newer versions exist, remains widely used in legacy academic environments and specific industrial workflows.

The most common use case for version 9.1 is within Excel via the Locate the Add-in REFPROP.XLS in your installation folder. Save a copy as REFPROP.XLA REFPROP.XLAM to your local "Add-ins" folder. Set Trusted Locations Open Excel and go to File > Options > Trust Center > Trust Center Settings Trusted Locations and add the folder C:\Program Files (x86)\REFPROP Activate the Add-in File > Options > Add-Ins In the "Manage" dropdown at the bottom, select Excel Add-ins (or browse to find the file if it's not listed). Fixing DLL Links : If functions return errors, press to open the Visual Basic Editor. Check if the path to REFPROP.DLL in the module matches your actual installation path. National Institute of Standards and Technology (.gov) 3. Installation on macOS