The program consists of three modules: preprocessor, solver and thermodynamic property routines. The preprocessor allows the user to interactively develop the model of a fluid network consisting of nodes and branches, and creates an input data file. The solver module reads the input data file to solve mass, energy and specie conservation equations at the nodes and the momentum conservation equations in the branches. The thermodynamic property routines compute "real fluid" thermodynamic and thermophysical properties for 12 fluids. The fluids are: helium, methane, neon, nitrogen, carbon monoxide, oxygen, argon, carbon dioxide, fluorine, hydrogen, water and kerosine (Rocket Propellant-1). The program also has the option of using any incompressible fluid with constant density and viscosity.

Fifteen different resistance and/or source options are provided for modeling momentum sources or sinks in the branches. The options are: pipe flow, flow through a restriction, pipe flow with entrance and/or exit losses, thin sharp orifice, thick orifice, square edge reduction, square edge expansion, rotating annular duct, rotating radial duct, labyrinth seal, face seal, common fittings and valves, pump characteristics, pump power and valve with a given loss coefficient.