Question: how many fdc are required?
Answer: For most fire sprinkler systems, NFPA 13 requires a 4-inch pipe for the FDC and the FDC is required to have two inlets. There is no other criterion in NFPA 13 requiring more than two connections. You might, however, encounter a FDC with a single-outlet when the FDC's piping goes into a 3-inch or smaller riser.