Which pipe is the sprinkler system feed main?

Which pipe is the sprinkler system feed main?

• A. The main drain
• B. The cross mains
• C. The riser
• D. The pipe connecting the riser to the cross mains

Answer: (D)

The key idea is how water moves from the building’s vertical supply into the floor’s sprinkler network. On a given level, the sprinkler feed comes through the pipe that ties the vertical riser to the horizontal cross mains. This link delivers water from the upward or downward vertical path into the floor’s distribution network, making it the actual feed main for the sprinklers on that level. The other components have different roles: the main drain is used for draining and testing the system, the cross mains run horizontally to feed sprinklers along the floor, and the riser is the vertical conduit that brings water to the floor but does not itself feed the horizontal distribution without that connecting pipe.

The key idea is how water moves from the building’s vertical supply into the floor’s sprinkler network. On a given level, the sprinkler feed comes through the pipe that ties the vertical riser to the horizontal cross mains. This link delivers water from the upward or downward vertical path into the floor’s distribution network, making it the actual feed main for the sprinklers on that level. The other components have different roles: the main drain is used for draining and testing the system, the cross mains run horizontally to feed sprinklers along the floor, and the riser is the vertical conduit that brings water to the floor but does not itself feed the horizontal distribution without that connecting pipe.