Create a new user environment variable named RPPrefix and set its value to your installation path (e.g., C:\Program Files\REFPROP ).
The most common issue is improper trust center configuration. Ensure you are not adding the add-in from a protected Windows folder. 5. Verifying Your Installation To confirm everything is working: Open REFPROP.exe . Go to Options > Fluids .
Installing NIST REFPROP 9.1 requires running the installer with administrative privileges and maintaining the default file structure to ensure functionality. Key steps include establishing trusted locations in Excel, enabling the REFPRP91.XLA add-in, and setting environment variables for proper integration. Read the full installation and linking guide at NIST . Linking REFPROP with Other Applications
The calling software (e.g., 64-bit Python) is trying to access a 32-bit DLL, or the system path is missing.
With a clean system, installing REFPROP 9.1 itself is straightforward. refprop 91 install
One of REFPROP's greatest strengths is its ability to be integrated into other programs via its (Dynamic Link Library). For version 9.1 to be compatible with 64-bit applications (like a 64-bit version of MATLAB), the file REFPRP64.dll must be present in your installation directory. This file provides the required 64-bit interface. Once this is in place, you can connect REFPROP to:
Note: Even on 64-bit Windows, REFPROP 9.1 installs to the Program Files (x86) folder because it is a 32-bit application.
The easiest way to use REFPROP 9.1 in Python is via the wrapper library ctypes or through the wrapper package ctREFPROP provided by NIST on GitHub.
Show you for density or pressure. Troubleshoot specific error codes. Create a new user environment variable named RPPrefix
Follow these steps to install the core database and user interface on a Windows machine. Step 1: Run the Installer
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Read and accept the NIST license agreement. Enter your User Name and Organization when prompted. Step 3: Choose Destination Location
Locate your downloaded RP91.EXE (or equivalent setup file). Right-click the file and select Run as administrator . Installing NIST REFPROP 9
While still widely used, REFPROP 9.1 has been superseded by later versions (10.0 and beyond). Users should ensure they are using the correct version for their needs and be aware that updates may contain critical improvements and bug fixes.
Press the , type environment variables , and select Edit the system environment variables .
: 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
Critical Note : If you plan to use REFPROP with third-party wrappers (like Python or MATLAB), changing this path to a simple directory without spaces, such as C:\REFPROP , can prevent path-parsing errors later.