In the technote Mark mentioned (#2), make note in particular of the two sections at the bottom: "What if I want to see how much pressure is available exactly at the total needed fire flow? Do I need to set the upper limit equal to the needed fire flow?" "Is there an easier way to check residual pressures at a hydrant, for a range of flows?" Basically one of the fields explained here is called "Pressure (Calculated residual @ total flow needed)" which shows you the exact pressure available at the needed fire flow value for that fireflow node. So, if you want to see exactly what the pressure will be at the needed fire flow, you can use this. Alternatively, you can right click on the fire flow node and choose Hydrant Flow Curve. This will show the relationship between pressure and outflow at the node. The basis behind automated fire flow is that you tell the program your constraints such as the minimum pressure, and it tells you if you're able to provide enough flow without violating those constraints. If they are violated (available fire flow less than the needed), the fire flow report indicates as such, and the engineer interprets that as a need to fix something in the model (such as upsize a pipe, after checking that the pressure constraints and zones were set up correctly).
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