Click here for a printable version of this article.

JULY 2011: SPRINKLER PROTECTION IN NON-STORAGE OCCUPANCIES

FM Global Data Sheet 3-26, Fire Protection Water Demand for Nonstorage Sprinklered Properties, is used to determine sprinkler system designs and hose demands for occupancies that are not considered storage occupancies in facilities. FM Global has taken steps to simplify this standard in recent years, just as they have done with their Data Sheet 8-9, Storage of Class 1, 2, 3, 4 and Plastic Commodities.

Data Sheet 3-26 now has three occupancy classifications - Hazard Category 1 (HC-1), Hazards Category 2 (HC-2), and Hazard Category 3 (HC-3). HC-1 has the lightest sprinkler system designs, and HC-3 has the heaviest sprinkler system designs. Hazard Category 4 (HC-4) has been removed due to a vague occupancy description that did not fit any comparable manufacturing sites. Protection options are now provided for ceiling heights up to 100 ft. with just three separate height ranges - up to 30 ft., 30 to 60 ft., and 60 to 100 ft. This is shown in Table 2 below.

Table 2 - Sprinkler Design Demands for Hazard Categories

Hazard

Category

Sprinkler Design Demand

(gpm/ft2)/ft2 (mm/min)/m2

Ceilings up to 30 ft (9m)

Ceilings from 30 to 60 ft

(9 to 18 m)

Ceilings from 60 to 100 ft

(18 to 30 m)

Wet

Dry

Wet

Dry

Wet

Dry

HC-1

0.1/1500

(4/140)

0.1/1500

(4/140)

0.2/2500

(8/230)

0.2/3500

(8/330)

See Table 2a

Not an option

HC-2

*0.2/2500

(8/230)

0.2/3500

(8/330)

0.2/2500

(8/230)

0.2/3500

(8/330)

See Table 2a

Not an option

HC-3

*0.3/2500

(12/230)

0.3/3500

(12/330)

0.5/3000

(20/280)

0.5/4000

(20/370)

See Table 2a

Not an option

In addition to making this standard easier to use, some of the occupancies have been shifted to lighter hazard categories. For instance, school and university classrooms, mineral processing, metalworking shops without hydraulic cutting operations, gymnasiums, and atriums have all been moved to HC-1.

Some of the designs are now easier to meet as well. The sprinkler design demand areas have been reduced for HC-3 occupancies with ceilings up to 30 ft. high. Also, the minimum water demand duration for HC-2 occupancies has been reduced to 60 minutes. In addition, the minimum K-factors have been reduced to K8 for HC-2 occupancies with ceiling heights up to 60 ft.

This standard has also been updated due to recent fire tests with extended coverage sprinklers. K11.2 and K14.0 extended coverage sprinklers can now be used in HC-2 & HC-3 occupancies with ceiling heights up to 30 ft. In the past, only NFPA allowed K14.0 heads in these occupancies. Additionally, extended coverage sprinklers no longer have a requirement to supply the most hydraulically remote nine sprinklers for HC-1 and HC-2 occupancies. The minimum sprinkler K-factors that are now allowed are listed in Table 4 below.

Table 4. Minimum Sprinkler K-Factors for Hazard Categories

Hazard Category

Ceiling Height, ft (m)

Up to 30 ft (9m)

30 – 60 ft (9 – 18 m)

Over 60 ft (18 m)

HC-1

5.6 or 5.6EC

(80 or 80EC)

8.0 (115)

25.2 or 25.2EC

(360 or 25.2EC)

HC-2

8.0 or 11.2EC

(115 or 160EC)

8.0 (115)

25.2 or 25.2EC

(360 or 25.2EC)

HC-3

11.2 or 11.2EC

(160 or 11.2EC)

11.2 (160)

25.2 or 25.2EC

(360 or 25.2EC)

Another significant change for this standard is that it is now considered acceptable to use storage sprinklers (or ESFR sprinklers) for areas of mixed storage and manufacturing, and nonstorage areas for both new and existing nonstorage occupancies. This is significant, as it can be costly to downgrade a sprinkler system from ESFR sprinklers to a standard control mode or nonstorage sprinkler.

Protection guidelines have also been added for water mist systems. Water mist systems can only be used with HC-1 occupancies under certain conditions. These conditions include, but are not limited to, the following: ceiling type, ceiling heights, design areas, nozzle spacing, pressure, and water supply and duration.

Risk Logic can help you determine the sprinkler protection needed for your nonstorage occupancy. Please contact us for additional information.