Some junctions have Special Conditions which alter the normal state of the junction. For example, a valve can be closed, a pump turned off, or a relief valve opened. Pipes can also be set closed which will effectively close the pipe to flow at both ends.

The special conditions are set in one of three ways:

• By selecting the junction(s) or pipe(s) on the Workspace and choosing Special Conditions from the Edit Menu

• By selecting the junction(s) or pipe(s) on the Workspace and clicking the Special Condition icon on the Toolbar

• By opening the junction’s or pipe’s Properties window and clicking the appropriate condition on the Optional tab

The pipes or junctions which have special conditions set are shown using a special symbol before the ID number (an "X" by default). This symbol can be customized in the Tools/User Options window.

When the special condition results in a section of the model being closed or "turned off", the pipes which will have zero flow are display as dotted lines. This indicates visually that they are cut off from flow; the junctions are outlined with a dotted line. The default dotted line can be changed in the Tools/User Options window.

The user can specify Special Conditions for Control Valves to be either closed or fully open. Similarly, Pumps can be turned off and either allow flow through or stop the flow.