# EPANET: Hydrant Rating Curve Example

Hydrant Rating Curve Example

This example illustrates how the Toolkit could be used to develop a hydrant rating curve used in fire flow studies. This curve shows the amount of flow available at a node in the system as a function of pressure. The curve is generated by running a number of steady state hydraulic analyses with the node of interest subjected to a different demand in each analysis. For this example we assume that the ID label of the node of interest is `MyNode` and that `N` different demand levels stored in the array `D` need to be examined. The corresponding pressures will be stored in `P`. To keep the code more readable, no error checking is made on the results returned from the Toolkit function calls.

#include "epanet2_2.h"
void HydrantRating(char *MyNode, int N, double D[], double P[])
{
EN_Project ph;
int i, nodeindex;
long t;
double pressure;
// Create a project
EN_createproject(&ph);
// Retrieve network data from an input file
EN_open(ph, "example2.inp", "example2.rpt", "");
// Open the hydraulic solver
EN_openH(ph);
// Get the index of the node of interest
EN_getnodeindex(ph, MyNode, &nodeindex);
// Iterate over all demands
for (i=1; i<N; i++)
{
// Set nodal demand, initialize hydraulics, make a
// single period run, and retrieve pressure
EN_setnodevalue(ph, nodeindex, EN_BASEDEMAND, D[i]);
EN_initH(ph, 0);
EN_runH(ph, &t);
EN_getnodevalue(ph, nodeindex, EN_PRESSURE, &pressure);
P[i] = pressure;
}
// Close hydraulics solver & delete the project
EN_closeH(ph);
EN_deleteproject(ph);
}