Choosing a pipe network object and right-clicking opens the Pipe Networks contextual tab. To change flow direction, select Change Flow Direction from the Modify panel. Change Flow Direction allows you to reverse the pipe’s understanding of which direction it flows, which comes into play when you’re using the Apply Rules command and when you’re annotating flow direction with a pipe label-slope arrow.
Changing the flow direction of a pipe doesn’t make any changes to the pipe’s invert. By default, a pipe’s flow direction depends on how the pipe was drawn and how the Toggle Upslope/Downslope tool was set when the pipe was drawn:
- If the toggle was set to Downslope, the pipe flow direction is set to Start To End, which means the first endpoint you placed is considered the start of flow and the second endpoint is established as the end of flow.
- If the toggle was set to Upslope when the pipe was drawn, the pipe flow direction is set to End To Start, which means the first endpoint placed is considered the end for flow purposes and the second endpoint the start.
After pipes are drawn, you can set two additional flow options—Bi-directional and By Slope—in Pipe Properties:
Start To End A pipe label-flow arrow shows the pipe direction from the first pipe endpoint drawn to the second endpoint drawn, regardless of invert or slope.
End To Start A pipe label-flow arrow shows the pipe direction from the second pipe endpoint drawn to the first pipe endpoint drawn, regardless of invert or slope.
Bi-directional Typically, this is a pipe with zero slope that is used to connect two bodies that can drain into each other, such as two stormwater basins, septic tanks, or overflow vessels. The direction arrow is irrelevant in this case.
By Slope A pipe label-flow arrow shows the pipe direction as a function of pipe slope. For example, if End A has a higher invert than End B, the pipe flows from A to B. If B is edited to have a higher invert than A, the flow direction flips to be from B to A.