sprinklernotes
Small Design Areas and Adding Additional Flow
You asked the following question: “In a NFPA 13 system, does Section 23.4.4.2.4 require additional water to be added when the remote area is 900 sf as allowed for quick response sprinklers per Section 11.2.3.2.3.1?” In response to your question, we have reviewed 2016 edition of NFPA 13 as the applicable standard. Our informal interpretation is additional water is not required to be added to the calculated system demand. Let’s start with Section 11.1.1 that states: A building or portion thereof shall be permitted to be protected in accordance with any applicable design approach at the discretion of the designer. This sentence tells us several things, one of which is that a single floor area can have multiple design basis, but the pertinent part is that there are multiple design options. Despite the fact that the different options provide differing degrees of protection, they are all considered equally acceptable. Section 23.4.4.2.4 is a relatively new option in how to address a portion of the building where the floor area is smaller than any of the applicable design options. For instance, a loading dock with a dry-pipe system with spray sprinklers that is only 400 sf. You can either pick up additional sprinklers from the area immediately adjacent to the loading dock as discussed in A.11.1.2 (not an option when the adjacent area is protected by a different type of sprinkler such as ESFR) or add additional water to the hydraulic calculation as discussed in Section 23.4.4.2.4. It states: Where the available floor area for a specific area/density design criteria, including any extension of area as required by 11.1.2 and Section 12.3, is less than the required minimum design area, the design area shall be permitted to only include those sprinklers within the available design area. This option is applied if the area is smaller than any of the area/density design criteria options in Section 11.2 allowed for the use of the area. One such design option is the reduction in remote area for the use of quick response sprinklers as dictated by Section 11.2.3.2.3.1. In conclusion, it is not necessary to calculate an area to the full size dictated by the density/area curves in Figure 11.2.3.1.1.
