It’s Friday, I’m lazy, and I don’t have a copy of my book in my grumpy hands. So, instead of writing a good post, I’m just going to point you at one.
Jeff Old, P.E. has posted a nice how-to on labeling pipes with flow based on Manning’s equation. He also solved the problem of using the Pipe Radius, which I logged as a bug and walked away from. I like his creative solution. Nicely done, Mr. Old!