Pressure drops in a pipeline can be calculated by using Bernoulli's equation. According to Bernouilli the pressure drop in an adiabatic pipeline is the result of three independent factors (frictional pressure gradient, momentum pressure gradient and gravitational pressure gradient). After integration the equation of Bernoulli is given by:

Two phase flow calculations can be done in two fundamental ways. Either by assuming an imaginary homogeneous mixture, in which the properties of the liquid and the vapor phase are combined to form mixture properties, or by asuming an heterogeneous mixture with a liquid and a vapor phase which may have different velocities.

The Fortran and spreadsheet programs written during the training period support one homogeneous model (the Dukler model) and two heterogeneous models (the Lockhart-Martinelli and a confidential model). The programs have four main calculation options:

- Upstream pressure calculation for a given downstream pressure and geometry.
- Downstream pressure calculation for a given upstream pressure and geometry.
- Maximum massflow calculation (no choked flow).
- Minimum diameter calculation (no choked flow).