A method to model a complex system of pipes. The model takes into account the physical processes in a tree-type piping system and provides for an accurate modeling of a real world tree-type piping system. In a preferred embodiment, a computer program is provided for analyzing models of dry pipe systems. The computer program includes a user interface and a computational engine. The user interface allows a model of a dry pipe system to be defined and the computational engine determines a liquid flow time through the model of the dry pipe system. The computational engine provides a verification of the liquid flow time in a model of a referential dry pipe system within 20% of an actual liquid flow time in the referential dry pipe system.