08-16 Force main size

Question: 08-16Code Section: 7Date: 18 June 2008OBC 2006 Reference:

Question: As a plumber, I was always taught that the sewage ejector (force main) discharge piping minimum size was 2”. Manufacturers are now selling ejector pit & pump systems with an 1½” (force main) discharge. Could your highly experienced group tell me if this is acceptable to them? I know the Code does not specify the minimum size (of the force main). The problem is that in this neatly sealed package it is hard to tell if a regular (foundation) sump pump is being used.

Interpretation: As there is no reference to size anymore, the code makes reference to the manufacturer and, therefore, the size should be determined by the manufacturer’s tapping. Sentence states the discharge piping shall be sized for optimum flow velocities at pump design conditions. Therefore, if the pump is designed to utilize a 1-1/2″ discharge, then it meets Code requirements. A sump pump and sewage ejector pump are two different types of mechanisms and have different purposes. One pumps clear water, the other pumps sewage. The manufacturers and the type of fixtures that discharge in it, should dictate the size of the pump and relative piping. A macerating toilet system has a 3/4″ discharge!

Interpretation: Approved at AMES 2008