Refprop 91 Install [ Tested — 2026 ]

Installing and enabling features for REFPROP 9.1 usually refers to setting up its integration wrappers (like the Excel Add-in) or ensuring the DLL and fluid files are correctly linked. How to Install the REFPROP 9.1 Excel Add-in

If you are looking to enable the REFPROP features within Excel, follow these steps provided by the NIST REFPROP-wrappers GitHub:

Locate the Add-in File: Find the REFPRP91.XLA file, typically located in your main REFPROP installation folder (e.g., C:\Program Files (x86)\REFPROP).

Open Excel Settings: Go to the Developer tab and click on Excel Add-ins.

Browse and Select: Click Browse, navigate to your REFPROP folder, select REFPRP91.XLA, and click Open.

Enable: Ensure the box for Refprp91 is checked in the list and click OK.

Verify VBA: To ensure functions work, open the Visual Basic editor (Alt + F11) and verify that Refprop91Code appears under your modules. Troubleshooting Common Setup Issues

Missing DLLs: If the functions return errors, ensure REFPROP.DLL is in your system path or the same directory as your application.

Fluid Path: REFPROP must be able to find its fluid and mixture files at runtime. For cross-platform or complex setups, CoolProp can be used as an interface to help REFPROP locate these files more reliably.

Legacy Version: Note that version 9.1 is an older release. Official support and the latest fluid models are found in Version 10.0, which is available through the NIST Standard Reference Database.

Are you trying to install REFPROP for a specific environment like Python, MATLAB, or C++?

Here’s a helpful feature for installing REFPROP 9.1 (assuming you meant version 9.1, since REFPROP 10.x is more common now — but if you meant NIST REFPROP 9.1, the following applies):

Step 2: Choose Installation Type

The installer offers two typical options:

Note: Even on 64-bit Windows, REFPROP 9.1 installs to the Program Files (x86) folder because it is a 32-bit application.

Step 1: Launch the Installer

Locate the Setup.exe file. Right-click and select "Run as Administrator." If User Account Control (UAC) prompts you, click "Yes."

Installation Guide for REFPROP 91

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.

System Requirements and Prerequisites Before beginning the installation, ensure your system meets the basic requirements for this legacy software:

Step-by-Step Installation Procedure

  1. Locate the Installer: Navigate to the directory containing your REFPROP 91 installation files. This is typically provided as a downloadable executable (e.g., REFPROP91.exe) or an ISO file. If you have an ISO, mount it to a virtual drive to access the setup file.

  2. Run as Administrator: Right-click the setup executable and select "Run as administrator." This is crucial; failing to do so may result in the software being unable to write necessary files to the system directories.

  3. User Account Control (UAC): If prompted by Windows User Account Control, click "Yes" to allow the program to make changes to your device.

  4. Installation Directory: The installer will prompt you to choose a destination folder.

    • Default Path: By default, the installer often suggests C:\Program Files (x86)\REFPROP. This is the recommended location.
    • Important Note for Legacy Users: If you are updating from a previous version (like 8.0), the path might default to C:\REFPROP. It is generally safer to install 9.1 in the Program Files directory to avoid file permission conflicts, though advanced users may prefer a root directory for easier access to fluid files.

  5. Completing the Setup: Follow the remaining on-screen prompts to finalize the installation. Once complete, you may launch the program. On Windows 10 or 11, if the program fails to launch or crashes immediately, right-click the REFPROP shortcut, select Properties, navigate to the Compatibility tab, and check "Run this program in compatibility mode for Windows 7."

Licensing and Activation REFPROP is commercial software. Unlike modern versions that utilize an online license manager, REFPROP 91 typically relies on a physical hardware key (dongle) or a specific license file (often named license.key or similar) placed in the installation directory.

Integration with Other Software Many users utilize REFPROP as a backend for Excel or MATLAB.

Troubleshooting Common Issues

Disclaimer NIST no longer officially supports Version 9.1, as it has been superseded by Version 10 and Version 11 (REFPROP 2024). Users are encouraged to upgrade to the latest version to ensure compatibility with the newest fluid models and Windows security updates.

Integrating REFPROP 9.1 (Reference Fluid Thermodynamic and Transport Properties) is a straightforward process, but it requires precise file placement to ensure it communicates correctly with external software like Excel, MATLAB, or Python. 1. Initial Extraction and Setup

The installation typically begins with the executable provided by NIST. Run the installer to unpack the high-accuracy property models and the graphical user interface. By default, the program installs to C:\Program Files (x86)\REFPROP

If you plan on using REFPROP with third-party wrappers (like Python’s

), many users prefer installing it to a simpler path without spaces, such as C:\REFPROP , to avoid path-string errors in code. 2. Linking the DLL The core of REFPROP is the REFPROP.DLL file. For the software to be "visible" to your system: System Environment Variables: Add the REFPROP installation folder to your Windows

. This allows other programs to call the DLL without you having to copy the file into every project folder. 32-bit vs. 64-bit:

Ensure you are using the version of the DLL that matches your calling application. REFPROP 9.1 includes both; the 64-bit version is often named REFPRP64.DLL 3. Integration with Excel To use REFPROP functions directly in spreadsheets: Open Excel and go to Options > Add-ins Excel Add-ins Browse to your REFPROP directory and select REFPROP.xlam Refprop.xla for older versions). Once enabled, you can use formulas like =Theoretical("T","Density", "SI", "Water") directly in cells. 4. Verification After installation, always run the standalone REFPROP GUI

first. If you can calculate a simple saturation table for a common fluid like Nitrogen, the underlying fluid files (.FLD) and mixture files (.MIX) are correctly placed. Are you planning to use REFPROP primarily through the Excel Add-in or via a programming language like

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

: Use the executable provided with your purchase (often via CD-ROM or digital download). Default Directory : By default, it installs to C:\Program Files (x86)\REFPROP

. It is highly recommended to keep this path, as many third-party wrappers look for it there by default. Verification : After installation, open the REFPROP.EXE

(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

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

Because REFPROP is a Windows-based Fortran program, macOS users must use a wrapper. Directory Setup : Create a folder named /Users/$USER/Library/Group Containers/UBF8T346G9.Office/ Copy Files : Copy your folders (must be capitalized) and the librefprop.dylib file into this new folder. Excel Setup REFPRP91.XLA

file specifically designed for Mac, which can be found in the NIST REFPROP-wrappers GitHub 4. Troubleshooting Common Issues Missing Fluids : Ensure the subdirectories are present in the main REFPROP folder. Path Environment Variable : If calling REFPROP from Python or MATLAB, adding C:\Program Files (x86)\REFPROP to your Windows System Environment Variables (Path) often resolves "DLL not found" errors. 32-bit vs 64-bit

: Ensure your Excel version (32 or 64-bit) matches the DLL version you are calling. REFPROP 9.1 typically provides both REFPROP.DLL (32-bit) and REFPRP64.DLL CoolProp can't load REFPROP v10 mixtures on Debian 9 #1829

REFPROP 91 Installation and Overview

Introduction

REFPROP (Reference Properties) is a comprehensive thermodynamic property database developed by the National Institute of Standards and Technology (NIST). REFPROP 91 is the latest version of this software, which provides accurate and reliable thermophysical property data for a wide range of pure fluids and mixtures. This write-up provides a detailed overview of the REFPROP 91 installation process and its key features.

System Requirements

Before installing REFPROP 91, ensure that your system meets the following requirements:

Installation Steps

  1. Download REFPROP 91: Visit the NIST website (https://physics.nist.gov) and navigate to the REFPROP download page. Select the version compatible with your operating system (Windows or macOS).
  2. Run the Installer: Once the download is complete, run the installer (.exe file for Windows or .dmg file for macOS). Follow the prompts to begin the installation process.
  3. License Agreement: Read and accept the license agreement.
  4. Choose Installation Location: Select the installation directory (default location: C:\Program Files\REFPROP on Windows or Applications/REFPROP on macOS).
  5. Select Components: Choose the components to install, including the REFPROP executable, property data, and any additional languages.
  6. Installation: The installer will copy the necessary files to your system.
  7. Activation: Upon first launch, REFPROP 91 will prompt for activation. Follow the on-screen instructions to activate the software using the provided license key.

Post-Installation

After installation, REFPROP 91 can be launched from the Start menu (Windows) or Applications folder (macOS). The software's graphical user interface (GUI) provides access to various features, including:

  1. Fluid Selection: Choose from a list of over 1,300 pure fluids and mixtures.
  2. Property Calculations: Calculate thermophysical properties, such as density, viscosity, and thermal conductivity.
  3. Phase Diagrams: Generate phase diagrams for pure fluids and mixtures.
  4. Data Export: Export calculated properties and phase diagram data to various formats (e.g., CSV, Excel).

Key Features

REFPROP 91 offers several key features:

  1. Accurate Property Data: REFPROP provides accurate and reliable thermophysical property data, based on internationally accepted standards.
  2. Comprehensive Fluid List: The software includes a vast list of pure fluids and mixtures, including refrigerants, hydrocarbons, and other common substances.
  3. User-Friendly Interface: The GUI is intuitive and easy to navigate, making it simple to perform calculations and generate phase diagrams.
  4. Export Options: Calculated properties and phase diagram data can be exported to various formats for further analysis.

Troubleshooting

If you encounter issues during installation or while using REFPROP 91, consult the NIST support resources:

  1. User Manual: Refer to the comprehensive user manual for detailed instructions and troubleshooting guides.
  2. FAQs: Visit the NIST REFPROP FAQ page for answers to common questions.
  3. Support Email: Contact NIST support via email for assistance with installation or technical issues.

Conclusion

REFPROP 91 is a powerful tool for calculating thermophysical properties of pure fluids and mixtures. By following the installation steps outlined above, users can easily install and activate the software. With its comprehensive fluid list, accurate property data, and user-friendly interface, REFPROP 91 is an essential resource for researchers, engineers, and students working with thermodynamic properties.

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, REFPROP 9.1 remains widely used in legacy academic environments and specific industrial workflows.

If you need to get REFPROP 9.1 up and running on your machine, follow this comprehensive installation and setup guide. 1. System Requirements & Prerequisites Before beginning, ensure your system meets the following:

OS: Windows XP through Windows 11 (REFPROP is natively a Windows application).

Permissions: Administrative privileges are required to write to the C:\Program Files (x86) directory.

Media: You must have the original installation files (usually an .exe installer or a folder containing SETUP.EXE). 2. Step-by-Step Installation Process Step 1: Run the Installer

Locate your REFPROP 9.1 installation file (often named REFPROP91.EXE or found within a disk image). Right-click the installer and select Run as Administrator. The InstallShield Wizard will launch. Click Next. Step 2: License Agreement and User Info

Read and accept the NIST license agreement. Enter your User Name and Organization when prompted. Step 3: Choose Destination Location

By default, the software installs to:C:\Program Files (x86)\REFPROP

Pro Tip: If you plan on using REFPROP frequently with Python, MATLAB, or Excel, some users prefer installing it to a shorter path like C:\REFPROP to avoid issues with spaces in file paths during API calls. Step 4: Complete the Installation

Follow the remaining prompts and click Install. Once finished, click Finish. You should now see a REFPROP icon on your desktop. 3. Post-Installation Configuration

Installing the software is only the first half. To make it useful, you usually need to link it to other tools. Adding REFPROP to System Environment Variables

To call REFPROP from any command line or external program, add it to your System Path:

Search for "Edit the system environment variables" in your Windows Start menu. Click Environment Variables.

Under "System variables," find Path, select it, and click Edit.

Click New and paste your installation path (e.g., C:\Program Files (x86)\REFPROP). Click OK on all windows. 4. Integrating with Third-Party Software Excel Integration Open Excel and go to File > Options > Add-ins. At the bottom, select Excel Add-ins and click Go. Click Browse and navigate to your REFPROP folder. Select REFPROP.xla (for older Excel) or REFPROP.xlam.

Ensure "Refprop" is checked in the list. You can now use functions like =PropSI(...). MATLAB Integration

Copy the refpropm.m file from the scripts folder in your REFPROP directory to your MATLAB work folder. You will also need to ensure the REFPROP.DLL is accessible in the system path. Python (CoolProp Wrapper)

Most Python users utilize the wrapper provided by CoolProp to access REFPROP 9.1: pip install CoreProp Use code with caution.

In your script, you will point the wrapper to your C:\Program Files (x86)\REFPROP directory to load the high-accuracy NIST fluid files. 5. Troubleshooting Common Issues

"DLL Not Found" Error: This usually means the system cannot find REFPROP.DLL. Ensure the installation folder is correctly added to your Windows System Path (see Section 3).

Fluid File Errors: If you get an error saying a fluid file (like NITROGEN.FLD) is missing, ensure you are running the application from the directory where the /fluids/ folder is located.

Excel Macros Blocked: If the Excel functions don't work, go to Trust Center > Trust Center Settings > Macro Settings and ensure "Enable all macros" (or "Disable with notification") is selected.

Installing REFPROP 9.1 is a straightforward process, but its utility depends on correct pathing and integration with your calculation tools. By following the steps above, you’ll have a robust thermodynamic engine ready for complex fluid analysis.

The installation of REFPROP 9.1 (Reference Fluid Properties) follows a specific process depending on whether you are using the standalone program or integrating it with Microsoft Excel. Core Installation Steps

To install the base version of REFPROP 9.1, you typically need the original installation media (CD-ROM) or a digital installer purchased from NIST.

Run the Installer: Execute the nist2391.exe or Setup.exe file from your installation source.

Default Directory: The program usually installs to C:\Program Files\REFPROP (or C:\Program Files (x86)\REFPROP on 64-bit systems).

System Requirements: It is designed for Windows environments; older documentation suggests compatibility back to Windows 95/NT, but it remains functional on modern Windows 10/11 systems with proper user permissions. Linking to Microsoft Excel

Integrating REFPROP 9.1 with Excel is one of its most common uses, allowing you to use thermodynamic functions directly in spreadsheets. Trusted Locations: refprop 91 install

Open Excel and go to File > Options > Trust Center > Trust Center Settings.

Under Trusted Locations, click Add new location and browse to your REFPROP folder (e.g., C:\Program Files\REFPROP). Add-in Setup: Go to File > Options > Add-ins.

At the bottom, select Excel Add-ins in the "Manage" box and click Go.

Click Browse and locate the REFPRP91.XLA file in your REFPROP folder. Ensure "Refprp91" is checked in the list. Special Cases: macOS and Version Conflicts

macOS Installation: Installing on Mac requires creating specific directory structures in the Group Containers folder for Office and manually copying fluids, mixtures, and the librefprop.dylib file.

Upgrading to Version 10: If you have REFPROP 10 installed, you can still use the 9.1 interface for backward compatibility. NIST provides a specific REFPRP91.XLA patch to help version 10 users run older spreadsheets without changing formula syntax.

Uninstallation Issues: If an installation fails, ensure you run the unins.exe utility in the REFPROP folder to clear registry entries before attempting a fresh install.

Are you planning to use REFPROP 9.1 primarily for Excel macros or as a standalone GUI for fluid property tables?

REFPROP | NIST - National Institute of Standards and Technology

While Version 10 is the current standard, REFPROP 9.1 remains in use for legacy compatibility and specific research workflows. The following comprehensive guide details the installation, system configuration, and common troubleshooting steps for setting up REFPROP 9.1. 1. Core Installation and System Requirements

REFPROP 9.1 is designed for Windows environments (XP through Windows 10) and requires approximately 10 MB of hard disk space.

Standard Setup: Run the installer executable (typically from a CD-ROM or digital download from NIST).

Default Path: The program usually installs to C:\Program Files (x86)\REFPROP.

Mini-REFPROP: For educational or student use, a free "Mini" version is available that follows a similar installation wizard process. 2. Linking with Microsoft Excel

Integrating REFPROP 9.1 with Excel is one of its most common use cases, allowing for thermodynamic calculations directly within spreadsheets. Enabling the Add-in: Open Excel and navigate to the Developer tab. Select Excel Add-ins and click Browse.

Locate REFPRP91.XLA in your installation directory (or your user's library for Mac). Ensure the "Refprp91" box is checked in the Add-ins menu. Trust Center Configuration:

To prevent Excel from blocking the DLL, you must add the REFPROP folder as a Trusted Location via File > Options > Trust Center > Trust Center Settings.

Code Access: You can view or modify the underlying wrapper code by opening the Visual Basic editor and double-clicking Refprop91Code under the REFPROP/Modules project box. 3. Advanced Integration (Fortran & Python)

Fortran: Users can compile the 27 source files into a single project or create a .lib file for easier linking in Windows environments. Recommended compilers include Intel Fortran or gfortran.

Python Wrapper: Install the official wrapper using pip install ctREFPROP.

Environment Variable: The RPPREFIX variable should point to your installation folder so Python can locate the necessary .DLL and fluid files. 4. Troubleshooting and Version Conflicts

Installing multiple versions of REFPROP can lead to "DLL Hell," where the system calls the wrong version of the calculation engine. Answers to Frequently Asked Questions - NIST Pages

The installation of NIST REFPROP 9.1 is a straightforward process for the standalone application, though linking it with tools like Excel requires additional manual configuration. 1. System Requirements

Before beginning, ensure your system meets these basic needs:

Operating System: Windows 98, 2000, XP, Vista, 7, 8, or similar (both 32-bit and 64-bit are supported).

Disk Space: Approximately 10–20 MB of available hard disk space. 2. Core Installation Steps

The primary installation typically occurs from a CD-ROM or an executable installer file.

Launch Installer: If using a CD, insert it and run the setup file (e.g., D:\NIST2391.EXE). If you have a downloaded version, double-click the .exe file (often named nist2391.exe).

Follow the Wizard: The setup wizard will guide you through the license agreement and destination folder selection. The default installation path is usually C:\Program Files\REFPROP or C:\Program Files (x86)\REFPROP.

Verification: Once finished, you can launch the graphical user interface (GUI) to calculate thermodynamic properties and view tables or plots. 3. Linking with Excel (Windows)

To use REFPROP functions directly in Excel spreadsheets, follow these steps to set up the Add-In:

Prepare the Add-In: Locate REFPROP.xls in your installation folder and save it as an Excel Add-In (.xla or .xlam) in the same directory.

Add Trusted Location: In Excel, go to File > Options > Trust Center > Trust Center Settings > Trusted Locations. Click Add new location and browse to your REFPROP folder (e.g., C:\Program Files\REFPROP).

Enable the Add-In: Go to File > Options > Add-ins. In the Manage drop-down at the bottom, select Excel Add-ins and click Go. Click Browse, navigate to your installation folder, select the .xla or .xlam file, and ensure it is checked in the list. Configure Environment Variables (Optional but Recommended):

Create a new user environment variable named RPPrefix and set its value to your installation path (e.g., C:\Program Files\REFPROP).

Add your installation path to the existing Path variable to ensure Excel can always locate the required DLLs (REFPROP.DLL or REFPRP64.DLL). 4. Common Troubleshooting Answers to Frequently Asked Questions - NIST Pages

How to Install REFPROP 9.1: A Complete Step-by-Step Guide NIST’s REFPROP (Reference Fluid Thermodynamic and Transport Properties) is the gold standard for researchers and engineers needing accurate thermophysical properties of fluids. While newer versions exist, REFPROP 9.1 remains widely used due to its stability and compatibility with legacy academic and industrial software.

If you are looking to get REFPROP 9.1 up and running on your system, this guide covers the installation process and how to link it with common platforms like Excel, MATLAB, and Python. 1. Prerequisites and System Requirements Before starting, ensure you have the following:

The Installer: REFPROP is a commercial product. You must have the REFPROP91.EXE setup file or the physical media purchased from NIST.

Administrative Rights: You will need permission to write to the C:\Program Files (x86) directory.

Operating System: Windows 7, 8, 10, or 11 (32-bit or 64-bit). 2. Running the Core Installation Launch the Setup: Double-click the REFPROP91.EXE file. License Agreement: Read and accept the NIST license terms.

Destination Folder: By default, the installer suggests C:\Program Files (x86)\REFPROP. Installing and enabling features for REFPROP 9

Pro-tip: If you plan on using Python or MATLAB extensively, some users prefer installing to a simpler path like C:\REFPROP to avoid permission issues or "Space in filename" errors in code.

Select Components: Ensure that "Full Installation" is selected so that all fluid files (.fld) and mixture files (.mix) are included.

Finish: Click install. Once finished, you will see a "REFPROP" shortcut on your desktop. 3. Integrating REFPROP 9.1 with Microsoft Excel

Most users utilize REFPROP via the Excel Add-in. Here is how to enable it: Open Excel and go to File > Options > Add-ins.

At the bottom, select Excel Add-ins from the "Manage" dropdown and click Go.

Click Browse and navigate to your installation folder (usually C:\Program Files (x86)\REFPROP). Select REFPROP.xlam (for modern Excel) or REFPROP.xla.

Important: You must also copy the file REFPROP.DLL from the installation folder to your C:\Windows\SysWOW64 directory (for 64-bit Windows) or C:\Windows\System32 (for 32-bit Windows). This allows Excel to "see" the engine. 4. Connecting to MATLAB

To use REFPROP 9.1 in MATLAB, you need a wrapper file (often provided in the MATLAB subfolder of the installation). In MATLAB, use addpath('C:\Program Files (x86)\REFPROP'). Use the refpropm.m function to call properties.

Example: density = refpropm('D', 'T', 300, 'P', 101.325, 'water')

Ensure your MATLAB bit-version matches the DLL (use a 64-bit wrapper if using 64-bit MATLAB). 5. Connecting to Python

Python users typically use the ctypes based wrapper or the popular CoolProp interface to call REFPROP.

Via CoolProp: If you have CoolProp installed, you can call REFPROP fluids by setting the "Alternative Path."

Direct Call: You will need to point your script to refprop.dll. Ensure your Python environment is the same "bitness" (32-bit vs 64-bit) as the DLL you are calling. 6. Troubleshooting Common Errors

"File Not Found" for Fluids: This happens if the program doesn't know where the /fluids folder is. Go to the REFPROP GUI, select Options > Paths, and ensure the path points to your installation folder.

DLL Errors in Excel: If you see #NAME? in Excel, it usually means the REFPROP.xlam is active but it cannot find the REFPROP.dll in the Windows system folders.

Permission Denied: If you cannot save changes to fluid mixes, run the REFPROP GUI as an Administrator.

Installing REFPROP 9.1 is straightforward, but the real work lies in the path configurations for your specific external software. Always ensure your .dll files are in a location where your system's PATH environment variable can find them.

REFPROP 9.1 Installation Guide: A Comprehensive Overview

REFPROP, short for Reference Fluid Thermodynamic Property Algorithms, is a widely used software package for calculating thermodynamic properties of fluids. Developed by the National Institute of Standards and Technology (NIST), REFPROP is an essential tool for engineers, researchers, and scientists working with fluid thermodynamics. In this article, we will focus on the installation process of REFPROP 9.1, providing a step-by-step guide and additional insights into the software's features and applications.

Introduction to REFPROP 9.1

REFPROP 9.1 is a significant update to the REFPROP series, offering improved performance, new features, and enhanced accuracy. The software provides a comprehensive database of fluid thermodynamic properties, including equations of state, vapor-liquid equilibrium, and transport properties. REFPROP 9.1 supports over 1000 fluids, including refrigerants, hydrocarbons, and other common working fluids.

System Requirements for REFPROP 9.1

Before installing REFPROP 9.1, ensure that your system meets the minimum requirements:

Downloading and Installing REFPROP 9.1

To install REFPROP 9.1, follow these steps:

  1. Download the installation package: Visit the NIST website (www.nist.gov) and navigate to the REFPROP download page. Select the REFPROP 9.1 installation package ( REFPROP91.zip or REFPROP91.exe) and save it to your local machine.
  2. Extract the installation files: If you downloaded the zip file, extract its contents to a temporary directory. If you downloaded the executable file, proceed to the next step.
  3. Run the installation program: Launch the installation program (REFPROP91.exe) and follow the prompts to begin the installation process.
  4. Select the installation type: Choose between a Typical or Custom installation. The Typical installation includes the standard database and user interface, while the Custom installation allows you to select specific components and databases.
  5. Choose the installation directory: Specify the installation directory, ensuring that you have sufficient disk space and permissions to write to the directory.
  6. Install the software: The installation program will copy the necessary files, create shortcuts, and register the software.

Post-Installation Steps

After installing REFPROP 9.1:

  1. Launch REFPROP: Double-click the REFPROP icon on your desktop or navigate to the installation directory and run REFPROP.exe.
  2. Update the database: REFPROP 9.1 includes an updated database. To ensure you have the latest data, select Database > Update Database from the menu.
  3. Configure the user interface: Customize the user interface by selecting View > Options and adjusting the settings to your preferences.

Using REFPROP 9.1

REFPROP 9.1 offers a user-friendly interface for calculating thermodynamic properties. The software supports various input formats, including:

Some common applications of REFPROP 9.1 include:

Troubleshooting and Support

If you encounter issues during installation or while using REFPROP 9.1, refer to the:

Conclusion

REFPROP 9.1 is a powerful tool for calculating thermodynamic properties of fluids. By following this installation guide, you can successfully install and configure REFPROP 9.1 on your system. With its comprehensive database and user-friendly interface, REFPROP 9.1 is an essential resource for engineers, researchers, and scientists working with fluid thermodynamics. If you have any questions or need further assistance, do not hesitate to contact the NIST REFPROP support team.

Integrating REFPROP 9.1 with Your Workflow

Once your refprop 91 install is successful, integration with external tools is where the real power emerges.

Final Recommendations

REFPROP 9.1 is a reliable workhorse, but it is aging. If you encounter persistent issues, consider:

  1. Installing to a short path – Avoid spaces or special characters. Use C:\REFPROP instead of the default to sidestep permission issues.
  2. Disabling antivirus temporarily – Some antivirus programs flag the REFPROP installer’s license mechanism as suspicious (false positive).
  3. Upgrading – If you rely on REFPROP for commercial work, consider upgrading to version 10 or 11, which have native 64-bit installers and better Windows 11 support.

With careful attention to compatibility mode and environment variables, REFPROP 9.1 will continue to serve as an accurate and indispensable tool for thermodynamic calculations for years to come.

This guide applies to REFPROP Version 9.1 (circa 2013). For the latest updates, please visit the official NIST REFPROP website.

Step 7 – Finalize Installation

Click Install and wait 1–3 minutes as files copy. At the end, uncheck “View Readme.txt” unless you enjoy highly technical legacy notes. Click Finish.

1. Overview

REFPROP (Reference Fluid Thermodynamic and Transport Properties) is the industry-standard software developed by the National Institute of Standards and Technology (NIST). Version 9.1 is a legacy iteration that remains widely used in industry for its stability and extensive database of pure fluids and mixtures. Unlike modern subscription models, 9.1 was typically distributed as a perpetual license, making the installation process distinct from newer versions.

Python Integration (via CoolProp or ctREFPROP)

While REFPROP 9.1 predates widespread Python support, you can still call its DLL using ctypes:

from ctypes import cdll, c_double
refprop = cdll.LoadLibrary(r'C:\Program Files (x86)\REFPROP\REFPROP.dll')

Note: This is complex. Many users prefer to use CoolProp, which wraps REFPROP, but CoolProp may require REFPROP 10.0+. Step 2: Choose Installation Type The installer offers