This article has been rewritten from the text of FM Global DS 8-9 "Storage of Class 1, 2, 3, 4 and Plastic Commodities" (March 2010, Interim Revision April 2026, 103 pages). The previous version's "storage height versus design selection" table, "Section 2.4 ESFR design", "K115-K240 CMSA" and "2 % slope" statements are not in the data sheet and have been removed. Every value below carries its section, table or figure number.
1. Scope and design flow (Sections 1.0, 1.3)
DS 8-9 covers Class 1, 2, 3, 4 and plastic commodities in rack, solid-piled, palletized, shelf and bin-box arrangements. Thresholds: 10 ft (3.0 m) for Class 1-3, 6 ft (1.8 m) for Class 4 and plastics; below these the storage is "low-piled" and goes to DS 3-26. Rubber tires, baled fiber, hanging garments, roll paper, baled waste paper, rolled nonwoven fabrics and carpets (8-series), flammable gases, liquids and solids (7-series), carousels (DS 8-33) and ASRS (DS 8-34) go to their own data sheets. Installation rules are in DS 2-0. The data sheet is intended for new systems and for modifying existing ones; evaluation of existing systems is handled through the FM Global service office.
The most practical advice in Section 1.0: consider future changes in storage arrangement, water supply and commodity before choosing an option, and where ceiling-only options exist, protect to the highest commodity hazard the ceiling height and water supply will allow. Section 1.3 provides two flowcharts: Figure 1 for solid-piled/palletized/shelf/bin-box and Figure 2 for rack storage. Both walk through Section 2.2.2 (commodity), 2.2.3 (flue spaces), 2.3.1-2.3.3 (system and ceiling sprinklers), Table 1 (sprinklers per branch line), Table 14 (hose and duration) and 2.3.6 (special options).
2. Eight commodity classes (Section 2.2.2)
The commodity class is determined per DS 8-1 (2.2.2.1). Protection is based on the most severe hazard present anywhere in the storage area (2.2.2.2). The ranking: Class 1 → Class 2 → Class 3 → Class 4 → cartoned unexpanded plastic → cartoned expanded plastic → uncartoned unexpanded plastic → uncartoned expanded plastic. Where the most severe hazard exists in relatively small amounts and protecting it creates a challenge, Fire Protection Scheme 8-9A in Section 2.3.4.9 (dedicated rack, horizontal barriers and quick-response in-rack sprinklers) can be used (2.2.2.3). The combustibility of pallets is included in the commodity class; noncombustible or metal pallets are preferred; idle pallet storage is protected per DS 8-24 (2.2.5). See the plastic storage article for the plastic classes.
3. Storage arrangements and flue spaces (Section 2.2.3)
- Solid-piled and palletized: vertically aligned flue spaces are maintained through the full height of storage; there are no minimum flue guidelines (2.2.3.1.1).
- Shelf storage: shelf depth not exceeding 750 mm; or depth up to 1.5 m with tier height up to 0.6 m; or depth up to 1.5 m with a 0.7 mm sheet-metal or 10 mm plywood vertical barrier down the centre parallel to the aisle ("back-to-back shelving") (2.2.3.1.2).
- Bin-box: solid shelf depth up to 3.0 m, tier height up to 1.5 m and vertical barriers perpendicular to the aisle not more than 1.2 m apart (2.2.3.1.3).
- Rack types: single-row when the depth is ≤ 1.8 m and aisles ≥ 1.2 m; double-row when the depth is 1.8-3.7 m with aisles ≥ 1.2 m; otherwise multiple-row (2.2.3.2.1.1-3).
- Open-frame: grated or slatted shelves at least 70 % open with adequate flues; solid shelves ≤ 20 ft² (1.9 m²) still count as open-frame (2.2.3.2.1.4-6). Racks not meeting the guidelines are treated as having solid shelves, whose size is defined by the surrounding flues (net 150 mm transverse, 75 mm at uprights; net 75 mm longitudinal in double-row; net 150 mm longitudinal in multiple-row racks) (2.2.3.2.1.9).
- Flue spaces: single-row racks, net 75 mm transverse flues every 1.4 m or 150 mm every 2.7 m; double-row racks, 75 mm longitudinal + 75 mm transverse every 1.4 m, or 75 mm longitudinal + 150 mm transverse every 2.7 m, and 150 mm transverse every 1.5 m where the longitudinal flue is under 75 mm; multiple-row racks, 150 mm longitudinal and 150 mm transverse flues every 1.5 m, or depth ≤ 6.1 m with aisles ≥ 2.4 m and 150 mm transverse flues every 1.5 m (2.2.3.2.2-2.2.3.2.4).
- Portable racks: treated as open-frame when the bottom is at least 70 % open; otherwise as solid-bottomed with area and height limits (2.2.3.3).
- Open-top containers: noncombustible containers are treated as closed-top when everything below them is noncombustible or they are on the bottom tier; combustible ones only when all are on the bottom tier; otherwise in-rack sprinklers per 2.2.4.3 (2.2.4).
4. Clearance, structure and venting (Sections 2.1, 2.2.6)
Maintain at least 3 ft (0.9 m) between the top of storage and the deflectors of standard-coverage ceiling sprinklers and at least 5 ft (1.5 m) for extended-coverage sprinklers (2.2.6). Adhering to the design guidelines eliminates the need for column and overhead steel protection (2.1.2). Racks are anchored against toppling, considering rack loads, absorbed fire water, water-filled in-rack piping and earthquakes (DS 1-2) (2.1.1.3). Heat and smoke venting and draft curtains are referred to DS 2-0; DS 8-9 gives no figures (2.1.3).
5. Storage sprinkler attributes (Section 2.3.3.2)
Only FM Approved sprinklers listed under "Storage Sprinklers (Ceiling-Level)" are used at ceiling level; the K-factor range is 11.2 (160) to 33.6 (480). K8.0 (K115) and smaller, on-off, ECLH and ECOH sprinklers are not approved as ceiling-level Storage sprinklers (2.3.3.2.1). Systems treated as wet use 70 °C, or 100 °C above a 38 °C ambient; dry and refrigerated-area systems use 140 °C (2.3.3.2.2-3). Quick-response elements and pendent orientation only in wet/antifreeze systems; standard-response and upright in any system type (2.3.3.2.4-7). The same K, orientation, RTI and temperature are used throughout an area (2.3.3.6). Designs are read by five attributes: K-factor, orientation, response, temperature, spacing (2.3.3.7.1).
6. Table map and reading rules (Section 2.3.3.7)
| Commodity | Solid-piled, palletized, shelf, bin-box | Open-frame racks, aisles ≥ 1.2 m |
|---|---|---|
| Class 1, 2, 3 | Table 2 | Table 7 |
| Class 4 and cartoned unexpanded plastics | Table 3 | Table 8 |
| Cartoned expanded plastics | Table 4 | Table 9 |
| Uncartoned unexpanded plastics | Table 5 | Table 10 |
| Uncartoned expanded plastics | Table 6 | Table 11 |
| Class 1-2 / Class 3, dry-pipe, ceilings over 9.0 m | Table 14a / 14b (Section 2.3.6.1) | |
| Class 1-4 and cartoned unexpanded plastics, ceilings over 12.2 m | Table 17b (Section 2.3.6.9) | |
Rules: every cell gives "number of sprinklers @ minimum pressure" and no interpolation is allowed (2.3.3.7.2); the design may be based on any row equal to or higher than the maximum ceiling height, and a higher row may be used when hydraulically better (2.3.3.7.2.2); green-highlighted options require 950 L/min hose and 60 min duration and are preferred; the minimum design area is 71 m² for 12 standard-coverage or 6 EC sprinklers, 60 m² for 10 and 54 m² for 9 sprinklers (2.3.3.7.2.3); pendent sprinklers may use the upright values with the same attributes (2.3.3.7.2.5); the hydraulic design is extended one branch line or sprinkler beyond the storage edge (2.3.3.5). Example: Table 7, 9.0 m ceiling, quick-response pendent K25.2 (K360) → 9 @ 20 psi (1.4 bar); K14.0 (K200) → 12 @ 50 psi (3.5 bar). The tables are detailed in the Storage sprinkler decision matrix.
Table 1, sprinklers per branch line and slope: for standard-coverage sprinklers and 9 or fewer sprinklers in the design, a ceiling slope up to 2 in 12 (10°) gives 3 sprinklers per branch line and up to 4 in 12 (18.5°) Equation 1; for 10-12 sprinklers, 1 in 12 gives 4 where the spacing is under 2.7 m otherwise 3, 2 in 12 gives 4 under 3.0 m otherwise 3, 4 in 12 gives 4; for 13 or more, Equation 1 up to 1 in 12 and, up to 4 in 12, Equation 1 (unobstructed) or 2 (obstructed). Non-integer results are rounded normally (2.3.3.7.2.6).
Ceiling higher than the table (2.3.3.7.3): for racks, a noncombustible false ceiling (at least 4.5 m beyond the storage, 2.3.3.7.3.1.1; designed per DS 1-12) or in-rack sprinklers; where the clearance to the ceiling exceeds 6.0 m, in-rack sprinklers at the top tier with 1.5 m of storage on it. For solid-piled storage, a false ceiling or conversion to racks.
7. In-rack sprinkler decision and design (Section 2.3.4)
Figure 3: are the racks open-frame, is there a ceiling-only option and can the water supply meet it, are open-top containers present, are there solid shelves over 6.0 m², does storage exceed 3.0 / 4.5 m, is the ceiling over 9.0 m? Negative branches lead to in-rack sprinklers. In-rack sprinklers are 70 °C, quick-response, minimum K8.0 (K115) above 115 L/min (2.3.4.3); face sprinklers within 450 mm of the rack face, deflectors at least 150 mm above the top of storage (2.3.4.5); horizontal arrangement IRAS(EO) or IRAS(E) (2.3.4.6); vertical increments per Figure 15 of 7.5 / 6.0 / 4.5 / 3.0 m; hydraulic design per Table 12 (Class 1-3: 6 or 10 sprinklers @ 85 L/min; Class 4 and plastics: 8 or 14 @ 115 L/min), ceiling design per Table 13. Details in the in-rack sprinkler article.
8. Hose demand, duration and system type (Sections 2.3.2, 2.3.5)
| Spacing | Sprinklers in design | Hose demand | Duration |
|---|---|---|---|
| Standard coverage | ≤ 12 | 250 gpm (950 L/min) | 60 min |
| 13-19 | 500 gpm (1,900 L/min) | 90 min | |
| ≥ 20 | 500 gpm (1,900 L/min) | 120 min | |
| Extended coverage | ≤ 6 | 250 gpm (950 L/min) | 60 min |
| 7-9 | 500 gpm (1,900 L/min)a | 90 mina | |
| ≥ 10 | 500 gpm (1,900 L/min) | 120 min |
a 950 L/min and 60 min when the maximum linear spacing is 3.7 m. At least 380 L/min is allowed for inside hose; 40 mm small hose lines not exceeding 30 m reach all storage areas and may be fed from a separate piping system, valved connections on the riser, adjacent systems or the ceiling sprinklers where in-rack sprinklers are separately controlled (2.3.5.2). System types may be wet, dry, antifreeze, preaction, deluge or refrigerated area; grid piping only for wet and antifreeze (2.3.2). Dry and similar systems have a maximum water delivery time of 40 s (most remote 4 sprinklers for unobstructed, 2 for obstructed ceilings; 60 s for single-sprinkler cut-off areas) (2.3.2.5). Single-interlock preaction systems are treated as wet or dry depending on detector spacing; other preaction types as dry (2.3.2.4). For Class 1-3 storage under ceilings over 9.0 m, Tables 14a/14b allow ceiling-only dry-pipe protection up to 16.5 m; the system size is limited to about 1,110 m² to meet the delivery time and plans are submitted to the FM Global service office for analysis (2.3.6.1).
9. Loss history: Table 18 (Section 3.2)
According to the data sheet, fires in storage occupancies have been controlled by the existing sprinkler arrangement whenever there were no major deficiencies; every uncontrolled loss involved inadequate water supplies, closed or partially closed valves, obstructed piping, missing sprinklers or flammable liquid/aerosol deficiencies. The study of rack storage losses gives two findings: in-rack sprinklers used with ceiling sprinklers are "overwhelmingly successful", and both damage and the number of operating sprinklers increase with storage and building height.
| Sprinklers operating during the fire | Percentage of fires controlled |
|---|---|
| 1 | 14 % |
| 2 or fewer | 32 % |
| 3 or fewer | 41 % |
| 4 or fewer | 49 % |
| 5 or fewer | 54 % |
| 10 or fewer | 77 % |
| 25 or fewer | 98 % |
Field note: the two flowcharts of DS 8-9 impose an order: commodity and arrangement first, then the table, then the water supply. On site the order is usually reversed: the sprinkler is chosen to suit the pump and tank at hand. Section 1.0 exists precisely for that: "protect to the highest commodity hazard the ceiling height and the available water supply will allow"; when today's Class 3 warehouse turns to cartoned plastics tomorrow, the table changes and the installation does not.
Quick checklist
- Scope: Class 1-3 above 3.0 m or Class 4/plastics above 1.8 m; special commodities and arrangements sent to their own data sheets
- Commodity class per DS 8-1; the most severe hazard in the area governs; pallet combustibility included
- Storage arrangement and rack type determined; open-frame conditions and flue spaces measured
- Clearance below the deflector 0.9 / 1.5 m; rack anchoring; venting per DS 2-0
- The sprinkler's five attributes chosen; compatibility with the system type (pendent and quick-response only wet) verified
- Applicable table and row selected; no interpolation; minimum design area and Table 1 branch-line count satisfied
- Ceiling higher than the table: false ceiling or in-rack route chosen
- In-rack decision by Figure 3; Figure 15, Table 12 and Table 13 applied where needed
- Hose demand and duration per Table 14; 40 s delivery on dry systems
- Highest hazard the ceiling and water supply allow targeted for future commodity and height changes
Frequently Asked Questions
From what storage height does FM DS 8-9 apply?
Section 1.0: 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; up to those heights the storage is low-piled and is protected per DS 3-26. Rubber tires, baled fiber, hanging garments, roll paper, carpets and similar commodities, and carousel (DS 8-33) or ASRS (DS 8-34) arrangements, go to their own data sheets.
Which tables give the sprinkler design in DS 8-9?
Tables 2 to 6 cover solid-piled, palletized, shelf and bin-box arrangements and Tables 7 to 11 open-frame racks, split by commodity into five groups. Tables 14a/14b give dry-pipe systems above 9.0 m and Table 17b ceilings over 12.2 m. Every cell reads "number of sprinklers @ minimum pressure" and no interpolation is allowed.
When does a rack count as open-frame?
Section 2.2.3.2: no solid shelves, or solid shelves not exceeding 1.9 m², grated or slatted shelves at least 70 % open, and adequate flue spaces. Single-row racks need 75 mm transverse flues every 1.4 m or 150 mm every 2.7 m; double-row racks additionally 75 mm longitudinal flues; multiple-row racks 150 mm longitudinal and transverse flues every 1.5 m. Otherwise the rack is treated as having solid shelves and Figure 3 decides.
What are the hose demand and water supply duration?
Table 14: standard coverage, up to 12 sprinklers 950 L/min and 60 min; 13 to 19 sprinklers 1,900 L/min and 90 min; 20 or more 1,900 L/min and 120 min. Extended coverage, up to 6 sprinklers 950 / 60, 7 to 9 1,900 / 90, 10 or more 1,900 / 120. At least 380 L/min for inside hose; 40 mm small hose lines not exceeding 30 m must reach all areas.
What are the water delivery time and sprinkler type for dry systems?
Section 2.3.2.5: maximum water delivery time 40 seconds; most remote 4 sprinklers for unobstructed and 2 for obstructed ceilings; 60 seconds for single-sprinkler cut-off areas. Dry systems use 140 °C standard-response upright sprinklers; pendent and quick-response sprinklers only in wet and antifreeze systems. For Class 1-3 storage under ceilings over 9.0 m, Tables 14a/14b allow ceiling-only protection up to 16.5 m with the system size limited to about 1,110 m².
References
- FM Global Property Loss Prevention Data Sheet 8-9, Storage of Class 1, 2, 3, 4 and Plastic Commodities, March 2010, Interim Revision April 2026: Sections 1.0-1.3 and Figures 1-2 (p.5-8), 2.1 (p.9), 2.2.2-2.2.6 (p.10-26), 2.3.1-2.3.2 (p.26-27), 2.3.3 and Tables 1-11 (p.27-40), 2.3.4 and Figures 3, 15, Tables 12-13 (p.41-58), 2.3.5 and Table 14 (p.62-63), 2.3.6.1 and Tables 14a/14b (p.63-65), 2.3.6.9 and Table 17b (p.79-80), 3.2 and Table 18 (p.80), Appendix A-B (p.83-103)
- FM Global data sheets: fmglobal.com; related sheets DS 2-0, DS 3-0, DS 3-26, DS 8-1, DS 8-24, DS 8-33, DS 8-34, DS 1-12, DS 1-2
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Download MEP Calc on the App StoreValues are transcribed from the FM Global data sheet above with section, table and figure numbers. This article is for general information; the design must be based on the FM Approval listing of the selected product and the current data sheet text, carried out by a qualified engineer and accepted by the insurer.