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);
}