Hydrant curves allow you to find the flow the distribution system can deliver at the specified residual pressure, helping you identify the system's capacity to deliver water that node in the network. Hydrant curves are useful when you are trying to balance the flows entering a part of the network, the flows being demanded by that part of the network, and the flows being stored by that part of the network.

The Hydrant Flow Curve Editor dialog displays the flow vs pressure table, which is computed by the program; the table is in part based on the Nominal Hydrant Flow and Number of Intervals values you define, which are used for formatting of the curve.

• Nominal Hydrant Flow: This value should be the expected nominal flow for the hydrant (i.e., the expected flow or desired flow when the hydrant is in use). The value for nominal flow is used together with the number of intervals value to determine a reasonable flow step to use when calculating the hydrant curve. A higher nominal flow value results in a larger flow step and better performance of the calculation. Note that if you choose a nominal hydrant flow that is too small and not representative of the hydrant then the high flow results on the resultant curve may not be correct since the calculation will not calculate more than 1000 points on the curve, for performance reasons.
• Number of Intervals: This value is used with the nominal flow value to determine the flow step to be used with the hydrant calculation. For example, a nominal hydrant flow of 1000gpm and number of intervals set to 10 will result in a flow step of 1000/10 = 100gpm. This results in points on the hydrant curve being calculated from 0 flow to the zero pressure point in steps of 100gpm. Note that if you have a number of intervals value that is too high then high flow results on the resultant curve may not be correct since the calculation will not calculate more than 1000 points on the curve, for performance reasons.
• Time: Choosing the time of the hydrant curve can affect the results of the curve. Choose the time at which you wish to run your hydrant curve and the corresponding pattern multipliers will be used for that time. This behaves the same way as an EPS snapshot calculation. You may also select multiple times in order to generate multiple hydrant curves for comparison

To define a Hydrant Flow Curve

• Choose the junction or hydrant element that will be used for the hydrant flow curve from the Hydrant/Junction pull-down menu or click the ellipsis button to select the element from the drawing pane.
• Enter values for Nominal Hydrant Flow and Number of Intervals in the corresponding fields.
• Choose a time step from the Time list pane.
• Click the Compute button to calculate the hydrant flow curve.