FM Global DS 2-0: Special Sprinkler Design for Storage Areas

Sprinkler design for storage areas uses two FM data sheets together. The design (sprinkler type, number of operating sprinklers and pressure, need for in-rack sprinklers, hose demand and duration) comes from FM Global DS 8-9; the installation rules (K-factor, spacing, distance below the ceiling, obstructions, in-rack sprinkler positions) come from FM Global DS 2-0 Section 2.5.4 (Storage Sprinklers). The commodity class is set by DS 8-1. Clause numbers refer to DS 2-0 October 2021, Interim Revision April 2025; DS 8-9 March 2010, Interim Revision July 2025; and DS 3-26 April 2019, Interim Revision April 2025.

When Storage Design Applies

• DS 8-9 scope (Section 1.0, p. 5): DS 8-9 applies when Class 1, 2 or 3 commodities are stored higher than 3.0 m, or Class 4 or plastic commodities higher than 1.8 m.
• Incidental storage (DS 3-26 2.3.2.1–2.3.2.3, pp. 6–7): Class 1–3 commodities up to 3.0 m high and 20 m² in area, and in HC-2 and HC-3 occupancies plastics up to 1.8 m high and 6 m² (about four pallets), are protected by the occupancy design (Table 2.3.1.10). Several such areas separated by aisles at least 2.4 m wide can still be treated as incidental.
• Low-piled storage (DS 3-26 2.3.3.1, p. 7): where the area limit is exceeded but not the height limit, protection follows DS 3-26 Table 2.3.3.1 together with the DS 2-0 installation and obstruction rules for Storage sprinklers.
• Commodity class: per DS 8-1. The April 2014 revision of DS 8-1 removed Class 4 as a separate category and combined it with cartoned unexpanded plastic (CUP), which is why DS 8-9 tables refer to “Class 4 and Cartoned Unexpanded Plastic”.

Storage Sprinklers (DS 2-0 Section 2.5.4.1)

• K-factors (Table 2.5.4.1.1, p. 111): K11.2 (K160), K14.0 (K200), K16.8 (K240), K19.6 (K280), K22.4 (K320), K25.2 (K360), K28.0 (K400) and K33.6 (K480). K11.2 with a 1/2 in. thread is accepted only as a retrofit for existing K8.0 (K115) or smaller sprinklers.
• Response (2.5.4.1.2): standard-response storage sprinklers may be used on wet and dry systems; quick-response sprinklers only on wet systems and not in the conditions listed in 2.5.4.1.2.2, such as spray application of ignitable liquids, vehicle assembly with fuelled tanks or large shielded areas.
• Venting (2.5.4.1.3.1): no gravity heat or smoke vents in buildings protected by ceiling-level storage sprinklers; where unavoidable, follow the flowchart in Figure 2.5.4.1.3.2(a) for vents of 4 ft² (0.4 m²) or less, or Figure 2.5.4.1.3.2(b) for larger vents (2.5.4.1.3.2).
• System type (DS 8-9 Section 2.3.2, p. 25): wet, dry, antifreeze, preaction, deluge or refrigerated-area according to ambient temperature; gridded piping is recommended only for wet and antifreeze systems.

Spacing and Distance Below the Ceiling

Ceiling height	Sprinkler	Linear spacing	Area per sprinkler
Up to 9.0 m	K160–K360 and K480 standard coverage	2.4–3.7 m	6.0–9.3 m²
Over 9.0 m	K160–K360 and K480 standard coverage	2.4–3.0 m	6.0–9.3 m²
All heights	K25.2EC (K360EC) quick response	3.0–4.3 m	9.3–18.2 m²

Source: DS 2-0 Table 2.5.4.3.1.1 (p. 128), unobstructed ceilings. Distance to walls is more than 100 mm and less than 50% of the maximum linear spacing (Figure 2.5.4.3.2). Under smooth ceilings the thermal element is 50–300 mm below the ceiling for K360EC, quick-response K160 and standard-response sprinklers, 50–325 mm for quick-response K200/K240 and 50–425 mm for quick-response K280 and larger; under non-smooth ceilings the lower limit is 100 mm (Figure 2.5.4.3.3.4, p. 131).

A clearance of at least 0.9 m is kept between the top of storage and the deflectors of standard-coverage ceiling sprinklers, and at least 1.5 m for extended-coverage sprinklers (DS 8-9 2.2.6.1–2.2.6.2, p. 25).

In-Rack Sprinklers (DS 2-0 2.5.4.6 and 2.2.1.6)

• Ceiling and in-rack sprinklers are arranged as separate systems with their own check valve, control valve and waterflow alarm (2.2.1.6.1). An in-rack system may be fed from the ceiling system when it has no more than 20 in-rack sprinklers, the water supply can meet both demands and a separate control valve is provided (2.2.1.6.2).
• One in-rack system covers at most 3,715 m² of floor area occupied by racks, including aisles, regardless of the number of levels (2.2.1.4.3).
• In-rack sprinklers are located within the rack structure, and face sprinklers no more than 450 mm in from the rack face (2.5.4.6.1–2.5.4.6.2).
• Deflectors at least 150 mm above the top of storage; where that cannot be achieved, in-rack sprinklers go at all flue space intersections, face and longitudinal (2.5.4.6.6).
• In-rack sprinklers and piping are arranged to avoid damage from material handling (2.5.4.6.8).

Hose Demand and Duration (DS 8-9 Table 14)

Sprinkler type	Sprinklers in ceiling design	Hose demand	Duration
Standard coverage	Up to 12 / 13–19 / 20 or more	950 / 1,900 / 1,900 L/min	60 / 90 / 120 min
Extended coverage	Up to 6 / 7–9 / 10 or more	950 / 1,900 / 1,900 L/min	60 / 90 / 120 min

For extended coverage with a maximum linear spacing of 3.7 m, a 7–9 sprinkler design may also use 950 L/min and 60 minutes (Table 14 note, p. 62). Where inside hose is provided, allow at least 380 L/min of the hose demand for it and add the balance to the sprinkler demand at the point of connection (2.3.5.1.1).

Quick Checklist

• Storage height and commodity class decide whether DS 8-9 or DS 3-26 applies
• Commodity class established per DS 8-1
• Protection option from the DS 8-9 tables, installation from DS 2-0 Section 2.5.4
• Spacing per Table 2.5.4.3.1.1 and distance below the ceiling per Figure 2.5.4.3.3.4
• Clearance above storage at least 0.9 m (1.5 m for EC sprinklers)
• In-rack positions and system separation per 2.5.4.6 and 2.2.1.6
• Hose demand and duration from DS 8-9 Table 14

Frequently Asked Questions

At what storage height does DS 8-9 apply?

Under FM DS 8-9 Section 1.0, DS 8-9 applies when Class 1, 2 or 3 commodities are stored higher than 3.0 m, or Class 4 or plastic commodities higher than 1.8 m. Storage below these heights is treated as low-piled or incidental storage and protected under DS 3-26.

Does back-of-house stock in a shop count as storage?

Under DS 3-26 2.3.2.1, Class 1 to 3 commodities up to 3.0 m high and 20 m² in area are incidental storage and are protected by the occupancy design. In HC-2 and HC-3 occupancies the limit for plastics is 1.8 m and 6 m² (2.3.2.2). If the area limit is exceeded but not the height, the low-piled storage rules apply; above the height limit, DS 8-9 applies.

How much clearance is needed above the storage?

FM DS 8-9 2.2.6.1 calls for at least 0.9 m between the top of storage and the deflectors of standard-coverage ceiling sprinklers, and 2.2.6.2 calls for at least 1.5 m for extended-coverage sprinklers.

Can in-rack sprinklers be fed from the ceiling system?

Normally not; DS 2-0 2.2.1.6.1 calls for separate ceiling and in-rack systems, each with its own check valve, control valve and waterflow alarm. Feeding from the ceiling system is accepted when there are no more than 20 in-rack sprinklers, the water supply can meet both demands and a separate, readily accessible control valve is provided on the in-rack supply (2.2.1.6.2).

How are hose demand and duration set for storage?

Per DS 8-9 Table 14: for standard-coverage sprinklers, up to 12 sprinklers in the ceiling design means 950 L/min for 60 minutes, 13 to 19 sprinklers 1,900 L/min for 90 minutes, and 20 or more 1,900 L/min for 120 minutes. For extended coverage the thresholds are 6, 7 to 9 and 10 sprinklers.

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