The Pipe Flow Expert software uses the Darcy-Weisbach equation to calculate the pressure drop (friction loss) in a pipe due to a specific flow rate. Friction factors are calculated using the Colebrook-White formula. These formulae give very accurate results for none compressible Newtonian fluids.

The Pipe Flow Expert software does not model changes in fluid characteristics due to changes in temperature. It is up to the user to allow for these effects by constructing systems that contain fluid zones that represent the average fluid characteristics for each fluid zone that is used. Pipe Flow Expert will allow you to create systems with up to 20 different fluid zones, each with a different fluid density and fluid viscosity.

The Pipe Flow Expert program is supplied with a fluid database, which contains fluid density and fluid viscosity entries for some common liquids and gases. Where the required fluid is not listed, you can add your own fluid data into the database, so it becomes available for future use.

Pipe Flow Expert now includes a compressible isothermal gas flow calculation engine. Further information about how the Pipe Flow Expert software handle compressible flow can be found here: Working with Compressible Fluids.