self scouring traps

[britkath]

There is a footnote in the UPC that states: "trap sizes shall not be increased to the point where the fixture discharge in capable of being inadequate to maintain their self -scouring properties", table 702.1. What exactly does that mean, and how do you know what size you can go up to?

 

[IFIXH20]

Self scouring = self cleaning. Basically a 1 1/2'' fixture drain will not clean a 3'' trap properly. Traps should be sized to the fixture drain it serves and not sized larger than the drain line it drains into.

 

[foplumbing]

hmm
11 year old post.... but does this "trap" requirement apply for the pipe size?
because there are many people who say using 4 inch piping leads to w/c not draining away properly (self scouring?)