This question pertains to all editions of NFPA 13
Does the system area limitation identified on Section 8.2.1 apply to individual system risers only or does it pertain to feed mains or standpipes that feed multiple systems as well.
We have a large building that has a vertical and horizontal combined standpipe system. The vertical standpipe feeds systems on each floor and the horizontal standpipe feed multiple systems on the lowest level. Each system riser, which contains a control valve, flow switch and drain, supports an area that is less than 52,000 square feet in a light hazard occupancy. However, the city believes we have exceeded the area allowed per system since all the systems on the first floor are supplied from a single feed main, in our case the horizontal standpipe. They believe that every system on each floor must originate from the underground entrance.
Their justification is that the horizontal standpipe is a single-point-of-failure. As such, we cannot rely on the standpipe to feed multiple system on a single floor.
Thanks in advance for your time and consideration,