I sometimes will use DI or Schedule 80 pipe from the meter through my POC equipment, where it will tee into a looped main line. On larger systems, to keep from having to, say, use 4" pipe at 5fps and have to bush that down to fit a 2" back flow device, I up the velocity to 7.5fps to keep the pipe a size smaller. What I notice is, if I change one main line's water velocity, they all change. Is there a way to allow separate velocities by main line type?
A follow-up question: is this even a good idea, allowing extra velocity through expensive POC equipment?