FM Global DS 8-34: Fire Protection for Automated Storage and Retrieval Systems

Automatic storage and retrieval systems (ASRS) are warehouses in which robots place small containers and trays into closely spaced racking and retrieve them again. Because the upright spacing, tier height and container materials are so different from conventional pallet racking, FM Global devotes a separate data sheet to them: DS 8-34 Protection for Automatic Storage and Retrieval Systems (July 2017, interim revision April 2026). This article summarises its scope, the general rules that apply to every ASRS type, and which section to use for each type.

Scope: What Does DS 8-34 Cover?

DS 8-34 (Section 1.0) covers Class 1 to 4 and plastic commodities in three types of ASRS:

• Horizontal-loading ASRS, Section 2.2: mini-load and shuttle systems handling small containers or trays.
• Top-loading ASRS (TL-ASRS), Section 2.3: containers stacked under a metal grid and accessed from above by robots (detailed article).
• Vertically enclosed ASRS, Section 2.4: packaged lift or carousel units operating inside a metal enclosure.

Outside the scope: arrangements using expanded plastic trays or containers, open-top containers with gridded (non-solid) bottoms, and commodities more hazardous than plastics. Ignitable liquids are referred to DS 7-29, aerosols to DS 7-31 and lithium-ion batteries to DS 7-112; these referrals were added in the July 2024 interim revision (Appendix B). Pallet-based "rack structure ASRS", with bays sized for a single pallet load, is protected under DS 8-9 rather than DS 8-34 (Appendix A), and carousel systems fall under DS 8-33.

General Rules for Every ASRS Type (Section 2.1)

• FM Approved equipment: use FM Approved equipment, materials and services wherever they are applicable and available (2.1.1).
• Construction: build in line with the FM 1-series data sheets; following DS 8-34 eliminates the need for separate protection of building columns and overhead steel (2.1.2.1, 2.1.2.3).
• Water weight: with open-top combustible containers, design the racking and floor for half of the containers below the in-rack sprinklers filling with water (2.1.2.5).
• Commodity: classify with DS 8-1 and design for the more severe of the stored product and the container or tray material (2.1.3.1).
• Clearances: at least 0.9 m between the top of storage and standard-coverage ceiling sprinkler deflectors, 1.5 m for extended-coverage sprinklers, and 100 mm for in-rack sprinklers (2.1.3.2).
• Ceiling design: the tables use a "number of sprinklers @ minimum pressure" format and must not be interpolated. With unobstructed ceilings the minimum design area is 53.5 m² for 9 sprinklers, 59.5 m² for 10, and 71.3 m² for 12 or more (2.1.4.5.1, 2.1.4.5.2.1).
• Adjacent areas: separate the ASRS from adjacent areas with full-height walls or draft curtains at least 0.6 m deep, unless both areas share the same ceiling design and RTI rating, or the higher-demand system is extended one sprinkler or one branch line into the other area (2.1.4.5.3).
• Electrical systems and robots: design the robot electrical system to an international safety standard such as IEC 60950-1, use lithium-ion batteries that have passed thermal runaway propagation testing to IEC 62619, and carry out infrared scanning of all ASRS electrical components at least annually (2.1.6).
• Final extinguishment: prepare a pre-incident plan with the fire service and FM covering how the fire will be reached, how the racking can be dismantled if needed, and how many containers may be removed and where they will go (2.1.5).

Horizontal-Loading ASRS: Mini-Load and Shuttle Systems (Section 2.2)

The difference between the two lies in the rack supports. In a mini-load rack the containers sit on angle irons, which divert most of the sprinkler discharge to the rack face and away from the transverse flue spaces; in a shuttle system the containers rest on slatted or mesh shelving and water can reach the flues (3.1.1, Appendix A).

• Transverse flue spaces: a net width of at least 38 mm where flues are nominally up to 0.6 m apart, 50 mm up to 0.75 m, 75 mm up to 1.5 m and 150 mm up to 3.0 m, all vertically aligned; where flues are more than 3.0 m apart or these conditions are not met, in-rack sprinklers are needed and the vertical distance between in-rack levels is limited to 3.0 m; vertical barriers are needed only under the conditions of 2.2.1.5 (2.2.1.4, 2.2.1.5).
• Section by container type: closed-top, noncombustible, solid-walled containers used throughout are protected for the surrounding occupancy (2.2.2, 2.2.5); closed-top combustible containers or trays of products that do not collect water use 2.2.3 and 2.2.6; open-top cardboard or unexpanded plastic containers use 2.2.4 and 2.2.7.
• In-rack sprinklers: FM Approved, quick-response, 160°F (70°C) storage sprinklers with the K-factor from the applicable table (2.2.1.6.2.2). The tables give the vertical distance between in-rack levels in metres; there is no blanket "every tier" rule.
• Detection: an FM Approved ceiling-level fire detection system over the storage area that sends an alarm to a constantly attended location and automatically shuts down the robots. It is not needed where closed-top noncombustible containers are used throughout (2.2.1.7).
• Hose demand and duration (Table 2.1.4.5.4): with standard-coverage ceiling sprinklers, 950 L/min for 60 min where the design has 12 or fewer sprinklers, 1,900 L/min for 90 min for 13 to 19, and 1,900 L/min for 120 min for 20 or more (2.1.4.5.4).
• Small hose connection stations: near the aisle access points, each of the two most remote stations delivering at least 190 L/min, 380 L/min in total (2.2.1.8).

Open-Top vs Closed-Top Containers

• Open-top container: a container with walls higher than 25 mm that has no cover, or a cover that does not keep water out (Appendix A). With open-top combustible containers, ceiling-only protection is possible only where storage does not exceed 3.0 m (2.2.4.1.1, 2.2.7.1.1).
• Closed-top container: a container with a solid cover that stays in place during a fire and keeps water out. Plastic containers with folding lids that do not seal completely should be treated as open-top (Appendix A, 3.1.1.3).
• Plastic containers: DS 8-34 covers unexpanded plastic containers; expanded plastic containers and trays are outside its scope. FM terminology does not use the NFPA Group A/B/C plastics groupings; classification follows DS 8-1 (1.0, 2.1.3.1).
• Cardboard containers: lower heat release than plastic, but they ignite more easily and burn faster, which drives the choice of horizontal in-rack arrangement (3.1.1.2).

Top-Loading and Vertically Enclosed Systems

• Top-loading (TL-ASRS): very early warning fire detection at ceiling level; on detection an alarm, robots sent to designated robot holding areas and charging stations shut down; a 100 mm curb and drainage around the array; and, for combustible containers, platforms or mezzanines for fire service access and a two- to four-hour water supply (2.3).
• Vertically enclosed units: noncombustible trays; automatic shutdown on detection or sprinkler operation; minimum K11.2 (K160) storage sprinklers at the top of units up to 7.6 m tall, and Table 2.4.3.3.3.1 pressures or intermediate sidewall sprinklers for units from 7.6 m to 16.8 m; supplementary gaseous protection considered for high-value contents (2.4).

Products with Lithium-Ion Batteries

Under DS 7-112 Section 2.4.7, finished products whose batteries are at a state of charge (SOC) of 30% or less are classified excluding the battery and protected per DS 8-34 with a wet system only. Products between 30% and 60% SOC must be placed in FM Approved non-propagating containers or solid-walled metal containers of at least 1.0 mm steel, stored only in a horizontal-loading ASRS and protected by wet ceiling and in-rack sprinklers. Products above 60% SOC must not be stored in an ASRS, and cells, modules or batteries that are not finished products are subject to separate provisions (DS 7-112 article).

Quick Checklist

• ASRS type (mini-load, shuttle, top-loading, vertically enclosed) confirmed against Appendix A; pallet-based rack structure ASRS referred to DS 8-9
• Commodity classified per DS 8-1; container or tray material and open or closed top recorded
• Out-of-scope conditions (expanded plastic containers, gridded-bottom open containers, ignitable liquids, aerosols, Li-ion) identified
• Transverse flue spaces measured against 2.2.1.4
• Ceiling and in-rack designs taken from the applicable tables without interpolation
• Detection alarms to a constantly attended location and shuts down the robots
• Small hose stations, pre-incident plan and fire service access defined
• Annual infrared scanning programme in place for robot electrical systems and batteries

Frequently Asked Questions

Is ceiling-only sprinkler protection enough for a mini-load ASRS?

In some cases, yes. For closed-top combustible containers or trays, ceiling-only protection requires transverse flue spaces per Section 2.2.1.4, aisles at least 1.1 m wide (1.2 m where the ceiling exceeds 9.1 m or uncartoned expanded plastics are stored), no uncartoned plastics stored directly on the rails, and a suitable option in Tables 2.2.6.1.2(a) to 2.2.6.1.2(d) (DS 8-34 2.2.6.1.1). With open-top combustible containers, ceiling-only protection is possible only where storage does not exceed 3.0 m (2.2.7.1.1).

What should the ASRS robots do when a fire is detected?

In horizontal-loading systems the detection system sends an alarm to a constantly attended location and automatically shuts down the robots (DS 8-34 2.2.1.7.3). In top-loading systems the robots are sent to designated robot holding areas and the charging stations are deactivated (2.3.2.1.4.4). Vertically enclosed units shut down automatically on detection or sprinkler operation (2.4.3.1.1).

What fire detection does DS 8-34 call for?

For horizontal-loading ASRS it calls for an FM Approved ceiling-level fire detection system installed per DS 5-48, which is not needed where closed-top noncombustible containers are used throughout (2.2.1.7). Over top-loading systems it recommends very early warning detection at ceiling level, with detector spacing under an unobstructed ceiling not exceeding 50% of the maximum listed in the Approval Guide (2.3.2.1.4.1, 2.3.2.1.4.2). No particular brand or technology is mandated.

Are pallet-based stacker crane warehouses covered by DS 8-34?

No. DS 8-34 covers systems handling small containers and trays. For pallet-based rack structure ASRS, with bays sized for a single pallet load and pallets resting on conveyors or supports perpendicular to the aisle, DS 8-34 Appendix A refers to FM DS 8-9.

How does protection differ between open-top and closed-top containers?

Open-top containers collect sprinkler water and expose their contents directly to flame, so the in-rack arrangement is tighter (at every other transverse flue space, with on-line spacing not exceeding 1.5 m) and the in-rack flow is higher, for example K11.2 (K160) at 380 L/min in a shuttle system (DS 8-34 Table 2.2.4.2.2.1(a)). For closed-top combustible containers the vertical distance between in-rack levels can range from 3.0 m to 12.2 m depending on the arrangement and commodity (Table 2.2.3.2.2.1(a)). Where closed-top noncombustible solid-walled containers are used throughout, protection is designed for the surrounding occupancy (2.2.2.1).

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