About hydrant nodes

Hydrant nodes allow detailed modelling of hydrants. These are of significance in fire flow analysis and analysis of mains flushing schemes.

In addition to the basic node definition, hydrant parameters and hydrant valve parameters are specified. Hydrant parameters include diameter, elevation and branch minor loss coefficient (loss due to change of flow direction and diameter change). Valve parameters include valve curve, valve diameter and valve minor loss coefficient.

Hydrant nodes can have multiple connections. Demand can be assigned to these nodes.

Calculation of hydrant flow

Calculation of hydrant flow is an iterative process, where for each iteration hydrant flow is calculated as follows:

(1) where: dh = Hi-Zh Hi = head for iteration i at hydrant node Zh = hydrant outlet elevation Kh = overall flow coefficient

Kh is calculated as:

(2) where: xb = branch minor loss coefficient xv = valve local loss for set hydrant opening Ah = hydrant cross section area Av = valve cross section area