Performing a forced fire flow simulation

Step-by-step Guide

InfoWorks WS Pro allows you to simulate forced fire flows in a network. Users can specify a hydrant where a set of user-defined fixed flows will be extracted. The flows are then applied consecutively, and the network is tested for velocity and pressure constraints. Where the constraints are violated, the point is deemed to have failed and the maximum available flow is reported.

This type of simulation can determine if customers will still be able to get water during a fire response. It can also give you an idea of what improvements or additions you need to make to a network so a hydrant can provide enough water during an emergency.

1. From the Model Group, click and drag Network into the workspace to open it.
2. In the Model Group, right-click Run Group and select New > Run to open the Schedule Hydraulic Run dialog box.
3. Title the new run "FFF".
4. Enable Experimental.
5. From the Model Group, drag and drop the Network, Control, and Demand diagram into their respective panels in the dialog box.
6. In the Run Type group box, expand the drop-down and select Fire Flow.

The Fire Flow Options dialog box opens.

7. In the Type of simulation: group box, enable Forced Fire Flow.
8. In the Fire Flow Node Location group box, click Choose location on GeoPlan, which prompts you to pick a hydrant in the GeoPlan.
9. Picking one automatically populates the Use existing node drop-down with the hydrant's ID number. In this example, hydrant ST29361601 is selected.
10. OR, expand the Use existing node drop-down to choose from a list of all hydrant IDs.
11. Populate the grid in the Test Flows (l/s) group box with flow values to test:
    1. For this exercise, type in the following values and press ENTER after each, starting in the first row: 5, 10, 15, 20, 25, 30, 35 and 40.
12. In the Failure criteria group box:
    1. Set the Maximum velocity to 4.
    2. Set the Minimum Fire Flow Node Pressure to 12.
    3. Set the Minimum system Pressure to 10.
    4. Enable Apply constraints to demand nodes only.

13. Click OK.
14. In the Schedule Hydraulic Run dialog box, click Save.
15. Click Run.
16. In the Model Group window, under Run Group, expand the FFF run to view the results of each of the various flows that were tested, as well as a Summary.

17. Right-click Summary and click Open as... > Forced Fire Flow Report.
18. Click OK.

A grid opens, showing the summary results for all tested flows.

19. Inspect the table and check the number of test flows that passed the failure criteria.

Note: The max velocity criteria in this exercise is disregarded, since the max velocity link is a short incoming pipe into one of the pump stations.

To see the results as a hydrant curve:

20. Right-click any row and select Hydrant Curve.
21. Review the hydrant curve for the selected hydrant.

22. Click Close.
23. Re-open the Schedule Hydraulic Run dialog box.
24. Under Fire Demand Data, change the Hydrant Testing Time to May 2nd, 2022, at 10:00am (the minimum pressure time at the hydrant node).

25. Re-run the simulation.
26. Repeat steps 16 – 18.
27. In the Grid Report, check the number of test flows that passed the failure criteria.