sprinklernotes
A Single FDC Serving Multiple Systems
You asked the following questions: “We have a warehouse with 20 ESFR systems. The building is supplied from a fire pump through a 10-in. underground loop with 10 individual underground stub-ins that supply two systems each. The current FDC piping connects to the 10-in. underground loop which supplies all of the 20 systems. Does this FDC configuration meet the requirements of NFPA 13 (2013 edition) paragraph 8.17.2.4.3? Under the same layout described above, the AHJ is requesting the FDC supplying the underground loop be removed and an FDC added to each system in the building and to be connected above the system control valve. This layout would effectively leave you with (10) FDCs on the building. The commentary from NFPA 13 (2013 edition) paragraph 8.17.2.4.3 appears to discourage against this layout. Is this the case? Under this proposed layout, there are areas in a fire situation where you would need to connect to (four) separately located FDCs to supplement the water supply. What opinion does NFPA have of this proposed layout?” In response to your question, we have reviewed NFPA 13, 2013 edition and the 2010 IBC as the applicable standard. Our informal interpretation is that the fire department connection can be connected to the underground supply. The statement from the IFC commentary for fire department connections (FDCs) is found in section 912.1. These connections give the fire department the capability of supplying the necessary water to the automatic sprinkler or standpipe system a sufficient pressure without pressurizing the underground supply and is simply describing the function of the fire department connection. This commentary is not prohibiting the underground supply piping being pressurized through the FDC. There is no wording in the IFC to support prohibiting the pressurization of the underground piping. Section 912.1 for installation indicates that FDCs shall be installed in accordance with the NFPA standards applicable to the system design and shall comply with section 912.2 through 912.5. Sections 912.2 through 912.5 address the location, access, signage, and backflow protection for FDCs. Thus, the installation is per NFPA standards such as NFPA 13, 13R, 14, and 20. Since NFPA 13 is applicable for this application, this standard clearly indicates that the FDC can be connected to an underground main. First, section 8.17.2.4.1 says that the FDC shall be on the system side of the water supply check valve. A backflow prevention device is considered a check valve in the application of NFPA 13. Next, section 8.17.2.4.4 indicates that the requirements of sections 8.17.2.4.2 and 8.17.2.4.3 shall not apply where the FDC is connected to the underground piping. This section reinforces that FDCs can be connected to underground piping. This is also illustrated in Figure A.8.17.1.1.4. The IFC also addresses private fire service mains in section 508.2.1 that states, “Private fire service mains and appurtenances shall be installed in accordance with NFPA 24.” The 2013 edition of NFPA 24 does address FDCs in section 5.9 so the FDC can supply underground mains. There is some confusion in section 8.17.2.5.2 of NFPA 13 and section 5.9.3.2 of NFPA 24 that says there shall be no shutoff valve in the FDC piping. Literally, when this sentence states, “fire department connection piping,” it means the piping between the inlet connections of the FDC and either the underground supply piping or the aboveground system piping. This sentence does not prohibit the installation of a control valve in the underground or system piping downstream from where the FDC piping connects. In fact, there are several criteria in NFPA 13 that support such an arrangement. Section 8.17.2.4.3 states, “for multiple systems, the fire department connection shall be connected between the supply control valves and the system control valves.” Clearly, this permits the FDC piping to be connected upstream from a control valve. Section 8.16.2.4.4 states, “The requirements of 8.17.2.4.2 and 8.17.2.4.3 shall not apply where the fire department connection is connected to the underground piping.” Again, the FDC can be connected upstream from a control valve. For the 2013 edition of NFPA 24, the committee also clarified this by modifying section 5.9.3.2 to read, “No shutoff valve shall be permitted in the piping from the fire department connection piping to the point that the fire department connection piping connects to the system piping.” Regarding where underground supply ends and fire water underground/fire line begins, this has been a topic debated by the NFPA 24 committee without a clear resolution. Figure A.3.3.11 of NFPA 24 shows an illustration indicating that the private service main begins at the property line. It will vary per the water jurisdiction where it may carry on to private property through easements up the control valve of the backflow prevention device or the water meter. In closing, if the fire hydrants are connected downstream of the FDC, those fire hydrants cannot be utilized to supply the FDC. This would produce a situation where the water from the fire hydrant is supplying the same line. The fire hydrant to be utilized for the supply to the FDC must be upstream of the check valve supplying the underground.
