Software Downloads

The following engineering calculation software is available for download at no charge:

Gas & Liquid Viscosity

This program is an add-in for Microsoft® Excel that calculates the viscosity of gases and liquids as a function of temperature. The program requires pivot point values for the specific gas or liquid for which you want to calculate the viscosity. These pivot point values are available in numerous publications such as Perry’s Chemical Engineer’s Handbook. A Help file and article on the method used to develop the equations are also available.

GLVISCOSITY AddIn>Add-In for Microsoft Excel: Gas/Liquid Viscosity Calculation
(24K) Zip file
This zip file contains the add-in, a help file and an example Microsoft Excel spreadsheet that shows how to use the add-in functions: GLViscosity.xla, GLViscosity.xls, GLViscosity.hlp
Reverse Engineering Nomographs Paper
(648K) pdf file
A paper that explains the methodology used to reverse-engineer the gas viscosity nomograph in Perry’s Handbook. This paper was adapted into an article in Chemical Engineering magazine (April 2003, pp 81-85)



This program is an add-in for Microsoft Excel that implements numerical methods which can be used to solve scientific and engineering problems. The numerical methods supported are numerical integration of a function or data, linear algebra, and numerical solution of ordinary differential equations. A Help file and spreadsheet example of how to use the methods are also available.

 Add-In for Microsoft Excel: Numerical Rx
(621K) Zip file
This zip file contains the add-in, a help file, and an example Microsoft Excel spreadsheet that shows how to use the add-in: Numerical Rx.xla, Numerical Rx Example.xls, NumericalRx.hlp
LorentzODE Spreadsheet
(449K) Zip file
This is a sample Microsoft Excel spreadsheet with graphs that shows the numerical solution to the famous Lorentz ODE equations. These equations were the one of the first examples of chaos theory.


This software is provided as is without warranty of any kind, express, implied, or statutory. Eldredge Engineering, P.A. further disclaims all implied warranties of merchantability or of fitness for a particular purpose. The entire risk arising out of the use or performance of the software and documentation remains with you.

In no event shall Eldredge Engineering, P.A. or anyone involved in the creation, production, or delivery of the software be liable for any damages whatsoever (including, without limitation, damages for loss of business profits, business interruption, loss of business information, or other pecuniary loss) arising out of the use of or inability to use the software or documentation, even if Eldredge Engineering, P.A. has been advised of the possibility of such damages.

By downloading, you agree to be bound by the warranty limitations set out above and to indemnify Eldredge Engineering, P.A. form any liabilities arising from the use of this software.