In Fire Fighting automatic wet sprinklers system how to do pipe sizing? Kindly first read the details then answer.

NFPA - gives tables and methods for sizing fire fighting wet sprinklers system based on hazards, sprinklers type & pipe materials etc.but all this procedure is applicable for a tree system design.

Considering loop system design for the same system, NFPA says you have to calculate pipe sizes by hydro lice calculations.

My question is about what is the step by step procedure & factors to consider while sizing  pipes based on  loop design?