Annex Examples of Sprinkler Locations in Small Rooms
“Due to Figures A.8.6.3.2.4(b), (c) and (d), the AHJ is interpreting that in small rooms with multiple sprinklers, the room can't be more than 15 ft in the least dimension (per Figure (b)) or 30 ft in the long dimension (per Figures (c) and (d)). The AHJ thinks only small rooms with a single sprinkler can be up to 16 ft 6 in. wide in one direction (per Figure (a)). Can a small room be 16 ft 6 in. wide with multiple sprinklers in a single row?” We have reviewed NFPA 13, 2013 edition as the applicable standard. Our informal interpretation is that the figures in the annex are only examples, but they do represent some maximum allowances. The small room definition is basically the definition of a compartment with the limitation of light hazard occupancy and floor areas not exceeding 800 sq. ft. The small room application is not limited to offices. The small room can apply to any light hazard occupancy such as corridors, lobbies, bathrooms, conference rooms, etc. When calculating the area of coverage, you simply take the area of the room and divide it by the number of sprinklers. The S x L rules do not apply but the maximum area of coverage must still be applied. The examples in A.8.6.3.2.4 are providing four possible configurations attempting to show the limiting constraints of all criteria including the maximum area of coverage. Per your examples, a room has one row of three sprinklers. One of the sprinklers is located 7 ft 6 in. from the wall, you have another sprinkler located close to the middle of the room 15 ft from the first sprinkler and 10 ft away from the third sprinkler, which is located 3 ft 10 in. off the wall at the far end of the room. Now the row of sprinklers is located 9 ft from one wall and 7 ft 6 in. to the other wall. This will give you a room size of 36 ft 4 in. by 16 ft 6 in. for a total square footage of 599.49. This equals to 199.83 sq. ft. area of coverage per sprinkler in that room. Example Figure A.8.6.3.2.4(a) may create some confusion because it is not a literal example since the A-B dimension shows a maximum of 7 ft 6 in. as does the B side, but the lower dimension reminds us that the total width is limited by the assigned area of coverage. Another limitation that should be noted is that the total room area cannot exceed 800 sq. ft. In closing, the referenced 16 ft 6 in. in one dimension for a room with a single sprinkler is an example of a maximum dimension. As stated in the standard, you can be 9 ft off a single wall leaving 7 ft 6 in. to the other wall creating an overall maximum of 16 ft 6 in. Technical Update is prepared by the Technical Services Dept. of the AFSA: Roland Huggins, a PE registered in fire protection engineering, Vice President of Engineering and Technical Services; Tom Wellen, a PE registered in fire protection engineering; Jason Williams, CET, Manager of ITM Technical Training; and Tom Noble, E.T., Technical Programs Specialist. This is provided with the understanding that the AFSA assumes no liability for this opinion or actions taken on it and they are not to be considered the official position of the NFPA or its technical committees. Copyright 2017, American Fire Sprinkler Association. All Rights Reserved -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.firesprinkler.org/private.cgi/sprinklernotes-firesprinkler.org/attachments/20170626/62564ecb/attachment.htm>
