Page 8 - Maximizing installation flexibility and storage capacity using ESFR Storage Sprinklers
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 Table 3 – K22.4, K25.2, K28.0 ESFR Sprinkler Minimum Aisle Width (ft/m) at 48 foot (14,6m) Ceiling
Note that the minimum aisle width for ceiling-only fire protection schemes above 45 feet (13,7m) is greater than compared to 45 feet (13,7m) and below. In order to be Listed or Approved, ESFR sprinklers must successfully pass full- scale fire testing as specified by testing agencies such as UL and FM.
As ceiling and storage heights increase, so do the challenges of addressing a fire with ceiling-only protection. High ceiling heights increase the time for the sprinkler to operate, leading to an increased fire size. The delay in sprinkler operation can lead to a phenomenon called aisle jump.
Full-scale fire testing is conducted with a rack storage arrangement as shown in Figure 2. There is a main array consisting of double row racks. Across from the main array on both sides and running parallel with the main array are single row racks, referred to during the test as “target arrays.”
The distance from the main array to the target array is the aisle width. Aisle jump occurs when the fire in the main array has increased in intensity such that its radiant heat ignites the commodity in the target array.
         Ceiling Height (ft/m)
48/14,6 8/2,4
6/1,8
Alternative ESFR-22.4
Tyco ESFR-25
ESFR-28
    5/1,5
   As shown is Table 3, the Tyco Model ESFR-25 has the UL Specific Application Listing with the narrowest aisle width. What does that mean in terms of total warehouse capacity? Before answering, let’s look at additional ceiling heights.
The FM 8-9 2020 edition identifies Storage Sprinkler (what are commonly referred to as ESFR sprinklers) fire protection schemes with ceiling-only fire protection up to 50 feet (15,2m) and 55 feet (16,8m). At the 50 foot (15,2m) ceiling level, Table 17b of FM 8-9 shows K-22.4, K-25.25, K-28.0 and K33.6 sprinklers are FM Approved with a 6 foot (1,8m) aisle width. At 55 feet (16,8m), the K-28.0 sprinkler is approved with an 8 foot (2,4m) aisle width while the K-33.6 sprinkler is approved with a 6 foot (1,8m) aisle width. Table 4 summarizes the FM Approved minimum aisle widths for ceiling-only protection at 50 feet (15,2m) and 55 feet (16,8m) using K-22.4, K-25.2, K-28.0 and K-33.6 sprinklers.
Table 4 – FM Approved Aisle Widths (ft/m) for K22.4, K25.2, K28.0 and K33.6 Storage (ESFR) sprinklers
50/15,2
           Ceiling Height (ft/m)
Tyco ESFR-22
Alternative A ESFR-22
6/1,8 6/1,8
Alternative B ESFR-22
Tyco ESFR-25
6/1,8
Alternative A ESFR-25
Alternative B ESFR-25
 6/1,8 6/1,8 6/1,8
ESFR-28
Tyco ESFR-34
 6/1,8
6/1,8
          55/16,8
N/A
N/A
N/A
N/A
N/A
N/A
8/2,4
6/1,8
         



























































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