Fire Department Connections (FDCs) are provided on buildings with fire sprinkler systems and/or standpipe systems, to allow the responding fire department to supplement the system’s water supply by pumping additional water into the building using an engine company. The two most common connection types for FDCs are 2.5-inch with National Hose (NH) internal threaded (female) swivel fittings and Storz connections. The type of connection required on a system should be determined by the local fire department based on the type of connections they use and their standard operating procedures. The numbers and/or sizes of the connection are determined by the type of systems they serve.
For sprinkler only systems, which are usually found in one- to three-story buildings, NFPA 13 (2019) §16.12.3 requires the FDC serving that system to have two 2.5-inch connections unless the following requirements are met:
- Local fire department does not conform to NFPA 1963, then the AHJ shall designate the connections.
- The use of threadless couplings (Storz) shall be permitted where required by the AHJ and is listed for such use.
- A single 2.5-inch connection may be used where the system riser is 3 inches or less.
NFPA 13 does not require additional inlets based on the sprinkler system demand – only two inlets are required. The system designer has the option to add more inlets, but only two are required.
For FDCs serving standpipe or combination standpipe/sprinkler systems, typically found in buildings that are four or more stories tall (or below ground), each FDC is required to have one 2.5-inch inlet for every 250 gpm of demand required by the standpipe system per NFPA 14 (2019) §7.12.3. The total demand for a system is determined by the number of risers provided on the system. For Class I and Class III standpipe systems with a single riser, a minimum flow rate of 250 gpm out of the two most remote hose connections (total of 500 gpm) is required. For a system with two standpipe risers, this adds an additional 250 gpm for the next riser (total of 750 gpm). As more standpipe risers get added, the quantity increases 250 gpm per additional riser for floors with areas of 80,000 sqft or less. Where floor area exceeds 80,000 sqft, the rate is 500 gpm for the second standpipe and 250 gpm additional for the third. The maximum total flow rate – regardless of the number of standpipe risers – for a sprinklered building is 1000 gpm, and 1250 gpm for a non-sprinklered building.
As most buildings with standpipes have at least two exit stairs, generally when using 2.5-inch inlets it is expected that there will be three 2.5-inch inlets (for 750 gpm standpipe demand). For three or more stairs, four 2.5-inch inlets (maximum 1000 gpm for a sprinklered building) would be expected. The demand for the sprinklers does not have to be added to the standpipe flow to determine the number of inlets.
While Storz inlets, which typically come in 4-inch or 5-inch sizes, are permitted for use, their flow rates are not addressed in NFPA 14 2019 or earlier editions. The proposed 2023 edition; however, will address the flow rates for both 4-inch and 5-inch Storz inlets. A new Section 10.7.3.1.1 states that the flow rate for a 4-inch Storz inlet assumes a flow of 500gpm per inlet and the new Section 10.7.3.1.2 states that the flow rate for a 5-inch Storz inlet assumes a flow of 750gpm per inlet.