Chapter 13 Encapsulated Storage “The storage is encapsulated Class III commodity stored on racks to a height of 12 ft protected as Ordinary Hazard (Group II). Is this correct or does the encapsulation make it "high rates of heat release” whereby only 8-ft storage is permitted?”
We have reviewed NFPA 13, 2013 edition that you indicated as the applicable standard. Our informal interpretation is that chapter 13 is silent regarding encapsulation. To start with, it’s logical to attempt to assign a different occupancy classification for encapsulated versus non-encapsulated but that doesn’t really provide a good answer. This approach would leave us with the only option of jumping to an EH1 (which is a 150 percent increase in the water demand). In reality, the encapsulation doesn’t really change the commodity classification. It does reduce the effectiveness of a given density’s ability to control the fire by stopping the pre-wetting of the product immediately adjacent to the fire. Considering the fact that chapter 13 does not address encapsulation, a literal interpretation is that no change or increase in density is required. The reality is that the NFPA 13 technical committee has simply not yet looked at this nuance. It will be addressed during the next cycle. As such, there are two choices. One is to ignore it until the committee addresses it. The other is to define a course of action and discuss it with the AHJ. I have identified the preliminary suggested change that will be made by our public input. Basically the requirements in chapters 14 and 16 will be the basis for requiring density modifiers. Solid pile storage requires no increase in density for storage between 12 ft to 15 ft (See A.14.2.1(3)). As such, no modifier is needed for solid pile heights up to 12 ft. It is interesting to note that there is a huge increase in density (approximately 300 percent) for heights between 15 and 20 ft and no guidance for heights beyond 20 ft (aka not allowed). On the other hand, rack storage does require an increase in density with chapter 16 applying several different approaches. For storage greater than 25 ft, it’s a flat 25 percent increase. For up to 25 ft, there are two approaches. For multiple row racks, it’s a flat 25 percent increase for Class I to III and 50 percent for Class IV. For single- and double-row racks, different figures are applied for non-encapsulated and encapsulated commodities. It basically works out to be an increase in density of 26 percent for Class I, 14 percent for Class II, 17 percent for Class III, and 22 percent for Class IV. A reasonable approach is to apply a 25 percent increase in density for all Class I-IV stored on racks without changing the size of the remote area. As previously stated, this must be discussed with the AHJ. ------------ 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; and Tom Wellen, a PE registered in fire protection engineering. 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 2016, 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/20160606/9ba3378b/attachment.htm>
