Applying Fireflow Velocity Constraints

Step-by-step:

Maximum velocity constraints can be applied to any fireflow analysis to ensure the available flow at the hydrant maintains the user-specified minimum pressure while the targeted pipes do not exceed the user-defined velocity. Results from this additional constraint can help identify pipes that are exceeding the maximum velocity or experiencing pipeline restrictions.

1. Open the appropriate .aprx file in ArcGIS Pro.
2. From the ribbon, InfoWater Pro tab, Project panel, click Initialize.

To perform the fireflow analysis only on the junctions (hydrants) in the domain:

3. On the ribbon, InfoWater Pro tab, Domain panel, click Domain Manager.
4. In the Domain Manager, for the Element Source, select Network.
5. Expand the adjacent drop-down and select All Pipes.
6. Click Add.
   

Note: The fireflow simulation will now be limited to the hydrants in the domain; however, the maximum velocity constraint will be applied to all pipes in the system.

7. Click Close to close the Domain Manager.

To run the simulation:

8. On the ribbon, InfoWater Pro tab, Analysis panel, click Run.
9. In the Run Manager, on the Fireflow tab:
   1. Enable Run Fireflow on Domain Only.
   2. Enable Velocity.
   3. Set the Max. Velocity value to 10.

Note: Ten feet per second is a common velocity constraint used for these simulations; however, check your local standards criteria and use that value if it differs.

4. Expand the Pipe Search Range drop-down and select Domain Pipes.
5. Click Run.

The Fireflow report opens automatically in the Report Manager.

10. If you are prompted to switch to the most recent output data, click Yes.

To identify which of these two parameters was most constraining to the hydrant available flow calculations:

11. Review the report.
12. Sort by the Hydrant Pressure at Available Flow field.
13. Sort by the Critical Pipe Velocity at Available Flow field.

The results within the Hydrant Pressure at Available Flow field that are equal to the user-defined Residual Pressure setting, or 20 psi in this example, indicate that the Hydrant Available Flow was constrained by the residual pressure. Values greater than the user-defined Residual Pressure mean that the Hydrant Available Flow was recalculated and constrained by the critical pipe velocity.

14. When you are finished reviewing the results, return to the Domain Manager and click Remove to remove all pipes from the domain.