Nja 13 Research Paper

“We have a walkway between buildings that is 15 ft wide. There are ceiling pockets on each side (15 ft wide, 3 ft across, and 2 ft deep) that separated form each other by columns. The total volume of the ceiling pockets is approximately 3,000 cu. ft. Are sprinklers required within the ceiling pockets?”

“We have reviewed the 2013 edition of NFPA 13 you indicated as the applicable standard. Our informal interpretation is protection should not be required within the pockets.

Normally, the total volume of unprotected ceiling pockets is 1,000 cu ft. The concern about multiple pockets is that it will excessively delay the activation of additional sprinklers. This occurs when the heat must flow past several pockets before reaching the sprinkler then flow through several more before reaching the next sprinklers. With the layout having no pockets between the sprinklers, there will be little delay created by the pockets. An additional influential factor is that it is a long narrow space. It’s recognized that fewer sprinklers can control fires in narrow compartments. In a regular room, the heat flows out in all directions and more sprinklers are exposed at the same distance from the centerline of the fire. In a narrow compartment, each additional ring consists of only 2 sprinklers and the ceiling jet is
It states – “the total volume of the unprotected ceiling pocket does not exceed 1,000 cu. ft.” This means that the volume of unprotected pockets within a portion of the compartment shall not exceed 1,000 cu. ft. Providing sprinklers within one pocket on each side of the corridor is the stopping point for calculating the total volume for the pockets in that portion of the compartment. As such, only 4 pockets are required to be protected. Keep in mind that unprotected pockets eliminates the option of applying the reduction of remote area for quick-response