21.2* Control Mode Density/Area Sprinkler Protection Criteria for Palletized, Solid-Piled, Bin Box, Shelf, or Back-to-Back Shelf Storage of Class I Through Class IV Commodities

Protection for Class I through Class IV commodities in the following configurations shall be provided in accordance with this section:

1. Nonencapsulated commodities that are solid-piled, palletized, or bin box storage up to 30 ft (9.1 m) in height
2. Nonencapsulated commodities on shelf storage up to 15 ft (4.6 m) in height
3. * Encapsulated commodities that are solid-piled, palletized, bin box, or shelf storage up to 15 ft (4.6 m) in height
4. Back-to-back shelf storage up to 15 ft (4.6 m) in height
5. Encapsulated storage of solid-piled and palletized Class I through IV commodities permitted in accordance with 21.2.3 for storage heights over 15 ft (4.6 m) up to and including 20 ft (6.1 m)

Where using ordinary temperature-rated sprinklers, a single point shall be selected from the appropriate commodity curve on Figure 21.2.2.1.

Where using high temperature-rated sprinklers, a single point shall be selected from the appropriate commodity curve on Figure 21.2.2.2.

The densities selected in accordance with 21.2.2.1 or 21.2.2.2 shall be modified in accordance with Figure 21.2.2.3 without revising the design area.

In the case of metal bin boxes with face areas not exceeding 16 ft² (1.5 m²) and metal closed shelves with face areas not exceeding 16 ft² (1.5 m²), the area of application shall be permitted to be reduced by 33 percent, provided the minimum requirements of 21.2.2.5 and 21.2.2.6 are met.

For storage greater than 12 ft (3.7 m), the design density shall not be less than 0.15 gpm/ft² (6.1 mm/min), and the design area shall not be less than 2000 ft² (185 m²) for wet systems or 2600 ft² (240 m²) for dry systems for any commodity, class, or group.

For storage greater than 12 ft (3.7 m), the sprinkler design density for any given area of operation for a Class III or Class IV commodity, calculated in accordance with 21.2.2, shall not be less than the density for the corresponding area of operation for ordinary hazard Group 2.

For back-to-back shelf storage, the design density shall be taken from Figure 21.2.2.1 for storage greater than 12 ft (3.7 m) and up to 15 ft (4.6 m) with no reduction for design density referenced in Figure 21.2.2.3.

Encapsulated storage over 15 ft (4.6 m) in height up to and including 20 ft (6.1 m) in height shall be limited to solid-piled and palletized storage.

Encapsulated storage over 15 ft (4.6 m) in height up to and including 20 ft (6.1 m) in height shall be protected by sprinklers with a K-factor of 11.2 (160) or larger.

Encapsulated storage over 15 ft (4.6 m) in height up to and including 20 ft (6.1 m) in height of Class I commodity shall be protected with a density/area of at least 0.46 gpm/ft² over 2000 ft² (18.7 mm/min over 185 m²).

Encapsulated storage over 15 ft (4.6 m) in height up to and including 20 ft (6.1 m) in height of Class II commodity shall be protected with a density/area of at least 0.53 gpm/ft² over 2000 ft² (21.6 mm/min over 185 m²).

Encapsulated storage over 15 ft (4.6 m) in height up to and including 20 ft (6.1 m) in height of Class III and Class IV commodity shall be protected with a density/area of at least 0.6 gpm/ft² over 2000 ft² (24.5 mm/min over 185 m²).