Page 12 - Maximizing installation flexibility and storage capacity using ESFR Storage Sprinklers

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It is interesting to note that given the same area:
• Total capacity with a 45 foot ceiling (13,7m) and a 4 foot (1,2m) aisle (13,056 as shown in the aforementioned example) is essentially the same as the total capacity with a 48 foot ceiling (14,6m) and a 5 foot (1,5m) aisle
• The calculation demonstrates that by increasing the aisle width to 6 feet (1,8m) there is a reduction of about 6% compared to what can be stored with the 5 foot (1,5m) aisle at 48 feet (14,6m) or a 4 foot (1,2m) aisle at 45 feet
• Increasing the aisle width to 8 feet (2,4m) decreases storage capacity by nearly 19%
The January 2020 edition of FM Global Loss Prevention Datasheet 8-9 now identifies FM Approved ceiling-only protection schemes at ceiling heights of 50 feet (15,2m) and 55 feet (16,8m) using quick response pendent storage sprinklers. The capacity calculation for these ceiling heights was performed based on FM approved aisle widths and the results are shown in Table 6.
The results of this calculation show that at the current FM Approved 6 foot (1,8m) aisle width and the 50 foot (15,2m) ceiling height:
• The maximum storage capacity based on number of pallets is essentially the same as what can be stored with a 4
foot (1,2m) aisle under a 45 foot (13,7m) ceiling or a 5 foot (1,5m) aisle under a 48 foot (14,6m) ceiling
• The 6 foot (1,8m) aisle under a 55 foot (16,8m) ceiling can increase the capacity by more than 10% over protection schemes available at 45 feet (13,7m), 48 feet (14,6m) and 50 feet (15,2m)
• The 8 foot aisle width under a 55 foot (16,8m) ceiling actually accommodates 13% less commodity than the scheme with 6 foot (1,8m) aisles and about 5% less than the Listed and Approved schemes at 45 foot (13,7m),
48 foot (14,6m) and 50 foot (15,2m) ceiling heights
While the above storage capacity calculations are based on a 200 foot x 200 foot (61m x 61m) warehouse space, the relative difference in percent basis will remain approximately the same given a fixed rack length and varying the length across the racks. Table 7 summarizes the pallet calculation on varying space lengths.
Table 6 – Total number of pallets for ESFR sprinklers approved with 50 foot (15,2m) and 55 foot (16,8m) ceiling heights
50/15,2 6/1,8 12,960 12,960 12,960
Ceiling height (ft/m)
Aisle Width (ft/m)
K-22.5 and K25-2 ESFR
K-28.0 ESFR
K-33.6 ESFR
55/16,8
6/1,8
N/A
N/A
14,400
55/16,8 8/2,4 N/A 12,480 N/A
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