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25.8.2 - in-rack protection for exposed group A plastic

Question asked by tender2 on Sep 22, 2018
Latest reply on Sep 22, 2018 by cdafd

So, just got the NFPA 13 (2019 edition) and came across the some doubts:-


1) stated "....the in-rack sprinkler system shall not be required to be hydraulically balanced with the ceiling sprinkler system". Does this statement mean we dont have to put ceiling sprinklers and rack sprinklers into the system for full hydraulic calculation? If say i do a separate calculation and got 1000 lpm @ 1 bar for rack, and 500 lpm @ 2 bar for ceiling, do i just match the highest figures together (1000 lpm @ 2 bar) to get my design flow and pressure?


2) Does in-rack sprinkler design 25.8.2 require horizontal barriers? i found hints of barrier requirement for 25.8.1 and 25.8.3 but couldn't find any for 25.8.2...anyone can clarify on this?


3) Lastly, although i think know the answer already, but since i'm already asking.....

referring to Table, number of operating sprinklers in double/multiple row racks for exposed group A plastic is 6 nos. for 2 rows of rack, right?