Cartoned Expanded Group A Plastics with ESFR Sprinklers “Commodity is cartoned, expanded Group A plastics stored on multiple row racks to 32 ft. There are (4) rack levels at about 8 ft. The building height is 40 ft. There are existing K17 ESFR pendants at the roof (originally designed for 52 psi). If the alternative protection method is utilized per 17.1.2.9 and horizontal barriers are installed on the bottom two tiers on the multiple row rack and in-rack sprinklers are designed and installed per 17.1.2.9, can the remaining commodity on the top two tiers of racks (open shelves) above the top level of horizontal barrier be protected by the existing ESFRs at roof level? The top two levels of rack storage is under 16 ft and the roof is 23 ft above the horizontal barrier (treating the upper level of in-rack above the topmost horizontal barrier to be treated as "floor"). Is this the intent of section 17.1.2.9.2, that says: “commodities that can be protected by the ceiling level sprinkler system shall be permitted to be stored vertically above the portions of the storage rack equipped as prescribed by 17.1.2.9?”
We have reviewed NFPA 13, 2016 edition as the applicable standard. Our informal interpretation is the ESFR can be applied to the area over the portion of the rack applying the alternative protection of 17.1.2.9. There are actually four separate questions that must be answered to determine the acceptability of your approach. These are: 1) Does 17.1.2.9 apply to the commodity? 2) Can it be applied throughout the warehouse? 3) What storage and ceiling height is applied to the storage in the rack above the portion of the rack applying the alternative method? 4) Can the existing ESFR protect the area outside of the portion of the rack applying the alternative method? Although Section 17.1.2.9 states it is applicable to:” The protection of Group A plastic commodities requiring a greater level of protection than is available from the overhead sprinkler system?”, it does not apply to exposed expanded Group A plastics. Figure 17.1.2.1 tells us that exposed expanded must be explicitly identified as such by the criteria. I don’t remember this restriction being discussed by the technical committee, but until it is explicitly addressed, it stands. Fortunately, you are not addressing an exposed commodity so it does apply. The next question is can it be applied to an entire warehouse. The criteria provides guidance for when the method is applied to only a portion of the rack, but the extent of application is not restricted. This partial rack criteria confirms this by starting with – “Where the storage rack will not be solely dedicated?” The third question is a bit more of a challenge. The reason for this is that when we have a mixed commodity where the lower tiers are one classification and the upper tiers are another, the storage height is combined rack height. This case though is quite different. As indicated in Section 17.1.2.9.6, the in-rack water demand is not added to the ceiling demand. It’s an interesting difference whereby the lower portion of the rack has no impact on the ceiling and is treated as if it were in a different compartment. The other criteria that indicate how it should be treated is where there is storage against the wall and located over an exterior doorway (aka no storage on the floor beneath it). Section 12.12.3.3 states: “Where idle pallet storage is above a door, the idle pallet storage height and ceiling height shall be calculated from the base of storage above the door using the applicable protection criteria referenced in Section 12.12.” This answers the questions on both storage height and ceiling height. Combining this section with the direction to treat the portion of the rack as a completely separate entity tells us to treat the highest barrier within the rack as the floor for the portion of the rack above the alternative protection. The final question is answered by Section 17.1.2.9.2 that explicitly identifies that storage can be above the alternative protection and that it can be protected by the ceiling sprinklers. With the storage and ceiling height starting at the upper barrier, one must be able to protect cartoned, expanded Group A plastics with a storage height of 16 ft and a ceiling height of 24 ft. Table 17.2.3.1 identifies this commodity can be protected with K-16.8 ESFR sprinklers at 52 psi to a storage height of 25 ft with a 32-ft ceiling. The required pressure is only 35 psi. 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/20170619/b2573831/attachment.htm>
