Georgia Fire Inspectors Association

A Main Drain Test Connection shall be provided for each sprinkler riser per NFPA 13 (2002), Section 8.16.4.1.1, and sized per NFPA 13 (2002), Table 8.15.2.4.2 ~ main drain piping size is based upon:

 Providing sufficient flow to properly determine the valve is fully open (the basis of the main drain minimum size);

 Provide a point on the riser to perform main drain waterflow testing (not specifically addressed in NFPA 13 [a minimum standard], but frequently used by inspectors, insurance representatives, engineers, investigators, etc. ~ see IRI’s IM.14.1.2.2 data sheet for more information on main drain waterflow tests and its appropriateness); and,

 Provide efficient draining of the system (note: inspector’s test piping is used for waterflow device testing, not waterflow testing).

Any common drain pipe (gang drain / drain riser) serving multiple main drain connections needs to be one pipe size larger than the largest main drain tied into it (Note: NFPA 13 (2002), Section 8.15.2.4.7 requires increasing the common drain piping for floor control valves for similar reasons) so that main drain flow (valve) and waterflow (supply) tests may be successfully performed on the risers when needed. An alternative would be to provide separate main drain discharge piping for each riser.