From the Help Documentation, Using the Pipe Sizing Dialog:
Note: The Pipe Sizing dialog cannot be used to size Sanitary system piping.
Personally I think that this note should be on the previous page, called Pipe Sizing.
While I'm at it, just to help me remember this bit too, regarding the branch sizing constraint options in the Pipe Sizing dialog (via Using the Pipe Sizing Dialog help page too):
- Calculated Size Only - The size of the selected pipe segment(s) is determined by the selected sizing method and is not otherwise constrained.
- Match Connector Size - The size of the selected pipe segment(s) in the branch is determined by the size of the connector used between the branch and the main, up until the first junction in the network. (emphasis mine)
- Larger of Connector and Calculated - The size of the selected pipe segment(s) is determined by larger of two (emphasis mine) determinants. If the connector size is smaller than the size calculated by the sizing method, then the calculated size will be used. If the connector size is larger than the size calculated by the sizing method, then the connector size will be used. For example, select this option to avoid supplying a plumbing fixture with a pipe segment that is smaller than the size of the connector on the fixture.