Hydraulically Calculating Sprinkler Systems Piping?

[FireScholar22]

About hydraulically calculating sprinkler systems - mathematically, I understand how to calculate the hydraulics, but the question that I have is what are the most important variables or elements that dictate the size and type of piping, other than the pressure required? When installing a system, how do you know which piping size to use? Also, does anybody know if scheduled piping is still being used today?

[CaptainGonzo]

The sprinkler design and installation company does all of the hydraulic calculations based on the water supply off the main and type of occupancy, which determines the type of system that will be required to meet code.