Some additional color for the multi-valve flow logic.
Nancy's max station flow is 24, let's say some other valves are 20, 18, 11, all such values. So with a multi-flow size set at 50gpm, why is it reporting 50gpm, when no two or three valves combined equal 50? As in, even though the multi-flow max was set to 50, shouldn't it be like 48gpm, equaling the sum of valves that most closely met the maximum?
The answer is in how it assigns the flow when sizing the mainline. So let's run through that. Let's say those 4 valves are at the end of the run, 24, 20, 18, 11. The pipe feeding the last valve, 24gpm, well clearly that pipe should be sized for 24gpm, we can all agree on that. Now backing up, to the segment feeding now the 2 valves at the end, our 24 and a 20. Well now we have 44gpm, pretty obvious we all agree on that, that segment will be sized at 44gpm. But now we get to the third valve, 18gpm. So the total downstream demand is 62gpm, definitely above our max. So what should that pipe segment be sized at? Should it be 44gpm, because that is still the maximum possible of the combination of downstream valves? Or should it be 50, because we have crossed that threshold of 50, even though not exactly in any valve combination downstream?
As we pass the 4th valve, the quandary continues, because now 20 + 18 + 11 = 49. So should that segment be sized at 49gpm, even though there is 73gpm downstream?
So, the decision we made, was once the total downstream flow is higher than the max gpm, it just simply uses the max gpm for consistency. Because the alternative, would be one segment sized at 44, the next at 49, and then likely 49 all the way back to the meter. So in a sense, that might be more accurate, but we felt that with best practices for planning for future work on the irrigation system, that the more simplistic logic with more consistency of pipe sizes made more sense.
Of course, totally open to ideas on the subject! It's always been fun explaining the logic when this question comes up, so I'm very curious what people think about it.
--J