Calculation of the pressure and flow profiles of a simulation has a major effect on the fidelity, reliability, robustness and performance of the dynamic simulator. A pressure-flow (P-F) network consists of several unit operations, connected by streams, where pressure and flow relations must be calculated. The resistance and volume balance equations produce these P-F relations within the flowsheet.This study compared two different solution methods for solving the resultant nonlinear simultaneous P-F equations, namely the Referred Derivatives method introduced by Thomas in 1997 and the Newton-Raphson method. In this comparison the advantages and disadvantages of the Referred Derivative method are provided. This paper also discusses the use of the Referred Derivatives method in solving flowsheets that include unit operations with holdup.