This article has been rewritten from the text of FM Global DS 8-9 (March 2010, Interim Revision April 2026). The previous version's Group A/B/C classification, "ESFR K360 plus in-rack at every level plus fire wall" table, 20 % height reduction and 4,500 m² zone are not in the data sheet and have been removed. Every value below is given with the DS 8-9 section, table or figure number. See the Storage sprinkler decision matrix for the general ceiling rules and the DS 8-9 overview for the design flow.
1. The four plastic classes and the scope threshold
Section 2.2.2.2 ranks commodity hazards from lowest to highest: Class 1, Class 2, Class 3, Class 4, cartoned unexpanded plastic, cartoned expanded plastic, uncartoned unexpanded plastic, uncartoned expanded plastic. Protection is based on the most severe hazard present anywhere in the storage area. The revision history (Appendix B) states that protection options for plastics no longer take Group type into account, only expanded/unexpanded and cartoned/uncartoned; the class is assigned per DS 8-1. In the tables Class 4 and cartoned unexpanded plastics share the same table (Tables 3 and 8).
Section 1.0: DS 8-9 applies where Class 4 or plastic commodities are stored higher than 6 ft (1.8 m); up to 1.8 m the storage is "low-piled" and is protected per DS 3-26. For Class 1-3 the threshold is 10 ft (3.0 m). Where a small amount of high-challenge commodity would force the whole area, Scheme 8-9A in Section 2.3.4.9 (dedicated rack, horizontal barriers, quick-response in-rack sprinklers) may be used (2.2.2.3).
2. Ceiling design tables: which plastic in which table
| Plastic class | Solid-piled, palletized, shelf, bin-box | Open-frame racks (aisles ≥ 1.2 m) |
|---|---|---|
| Cartoned unexpanded (with Class 4) | Table 3 | Table 8 |
| Cartoned expanded | Table 4 | Table 9 |
| Uncartoned unexpanded | Table 5 | Table 10 |
| Uncartoned expanded | Table 6 | Table 11 |
All tables share the same format: maximum ceiling height rows; wet-system 70 °C pendent (quick- and standard-response), wet 70 °C upright and dry-system 140 °C upright columns; each cell "number of sprinklers @ psi (bar)". No interpolation (2.3.3.7.2). Selected rows of the quick-response pendent columns follow; for the full tables see pages 33-39 of the data sheet.
Table 10: uncartoned unexpanded plastics, open-frame racks (wet, 70 °C, quick-response pendent)
| Max. ceiling | K11.2 (K160) | K14.0 (K200) | K16.8 (K240) | K22.4 (K320) | K25.2 (K360) | K25.2EC |
|---|---|---|---|---|---|---|
| 10 ft (3.0 m) | 15 @ 10 (0.7) | 15 @ 7 (0.5) | 15 @ 7 (0.5) | 9 @ 20 (1.4) | 9 @ 20 (1.4) | 6 @ 20 (1.4) |
| 15 ft (4.5 m) | 15 @ 50 (3.5) | 12 @ 32 (2.2) | 12 @ 22 (1.5) | 9 @ 25 (1.7) | 9 @ 20 (1.4) | 6 @ 60 (4.1) |
| 20 ft (6.0 m) | – | 9 @ 50 (3.5) | 9 @ 35 (2.4) | 9 @ 25 (1.7) | 9 @ 20 (1.4) | 6 @ 60 (4.1) |
| 25 ft (7.5 m) | – | 10 @ 50 (3.5) | 10 @ 35 (2.4) | 10 @ 25 (1.7) | 10 @ 20 (1.4) | – |
| 30 ft (9.0 m) | – | 15 @ 50 (3.5) | 15 @ 35 (2.4) | 10 @ 50 (3.5) | 10 @ 40 (2.8) | – |
| 40 ft (12.0 m) | – | – | – | 12 @ 75 (5.2) | 12 @ 60 (4.1) | – |
Table 11: uncartoned expanded plastics, open-frame racks (wet, 70 °C, quick-response pendent)
| Max. ceiling | K11.2 (K160) | K14.0 (K200) | K16.8 (K240) | K22.4 (K320) | K25.2 (K360) | K25.2EC |
|---|---|---|---|---|---|---|
| 10 ft (3.0 m) | 15 @ 10 (0.7) | 15 @ 7 (0.5) | 15 @ 7 (0.5) | 9 @ 20 (1.4) | 9 @ 20 (1.4) | 6 @ 20 (1.4) |
| 15 ft (4.5 m) | 15 @ 50 (3.5) | 12 @ 32 (2.2) | 12 @ 22 (1.5) | 9 @ 25 (1.7) | 9 @ 20 (1.4) | 8 @ 35 (2.4) |
| 25 ft (7.5 m) | – | 12 @ 75 (5.2) | 12 @ 52 (3.6) | 9 @ 32 (2.2) | 9 @ 25 (1.7) | – |
| 30 ft (9.0 m) | – | 12 @ 100 (6.9) | 12 @ 70 (4.8) | 12 @ 50 (3.5) | 12 @ 40 (2.8) | – |
| 40 ft (12.0 m) | Single option: 20 @ 75 psi (5.2 bar) | |||||
Cartoned expanded plastics in racks (Table 9) under a 9.0 m ceiling: K14.0 12 @ 50 psi (3.5 bar), K16.8 12 @ 35 psi (2.4 bar), K22.4 12 @ 25 psi (1.7 bar), K25.2 12 @ 20 psi (1.4 bar); at 12.0 m K22.4 12 @ 75 psi (5.2 bar), K25.2 12 @ 60 psi (4.1 bar). In the solid-piled and palletized Tables 4 and 5 the 10.5 m row gives K22.4 12 @ 63 psi (4.3 bar) and K25.2 12 @ 50 psi (3.5 bar), and the 12.0 m row K22.4 12 @ 75 psi and K25.2 12 @ 60 psi; uncartoned expanded plastics (Table 6) at 9.0 m give K14.0 9 @ 100 psi (6.9 bar), K16.8 9 @ 70 psi (4.8 bar), K22.4 9 @ 50 psi (3.5 bar), K25.2 9 @ 40 psi (2.8 bar), and at 12.0 m a single option of 20 @ 75 psi (5.2 bar). For uncartoned plastics the pressure climbs to 6.9 bar as the K-factor shrinks; choices other than K22.4 and K25.2 inflate the water supply quickly.
Where the ceiling exceeds the highest row of the table, Section 2.3.3.7.3 applies: a noncombustible false ceiling (extending 4.5 m beyond the storage) or in-rack sprinklers; where the clearance between the top of storage and the ceiling exceeds 6.0 m, in-rack sprinklers are added at the top tier and storage on the top tier is limited to 1.5 m.
3. Ceilings over 12.2 m: Table 17b exclusion and the 2.3.6.9.5 exception
Section 2.3.6.9.4: the Table 17b designs for ceilings over 12.2 m (K22.4 to K33.6, 15.2 and 16.8 m) apply only to Class 1-4 and cartoned unexpanded plastics; cartoned expanded plastics and all uncartoned plastics are excluded. For these plastics a ceiling over 12.2 m requires in-rack sprinklers or a false ceiling.
Section 2.3.6.9.5 gives an exception for solid-piled, palletized, shelf and bin-box storage: maximum 25 ft (7.6 m) storage, maximum 45 ft (13.7 m) ceiling, commodities up to and including uncartoned unexpanded plastics; wet system (pre-action systems do not qualify), quick-response 70 °C minimum K25.2 (K360) pendent Storage sprinklers installed per DS 2-0; design 12 sprinklers @ 60 psi (4.1 bar), hose 250 gpm (950 L/min), duration 60 min.
4. In-rack sprinklers: vertical increments and design for plastics
Whether in-rack sprinklers are needed is decided by Figure 3 (see the in-rack sprinkler article). Plastic-specific values:
- Vertical increments (Figure 15): in open-frame racks, not exceeding 6.0 m where the highest hazard is below cartoned unexpanded plastics; 4.5 m where it is below cartoned expanded plastics (i.e. cartoned unexpanded plastics); 3.0 m for cartoned expanded and uncartoned plastics. In racks with solid shelves over 2.0 m², 4.5 m below cartoned plastics and 3.0 m for plastics. Storage above the top level does not exceed 3.0 m.
- In-rack design (Table 12): Class 4 and plastics, 8 sprinklers for one level or 14 sprinklers (7 on 2 levels) for two or more, minimum 30 gpm (115 L/min) per sprinkler; minimum pressure 7 psi (0.5 bar); hydraulic balance with the ceiling at the connection.
- Ceiling design with in-rack sprinklers (Table 13): cartoned plastics use the 10, 15 or 20 ft rows of Table 8; uncartoned plastics with IRAS(EO), 1.5 m of storage above the top level and 1.5 m clearance use Table 8 @ 10 ft, 6.0 m clearance Table 8 @ 15 ft; with 3.0 m of storage, clearance 1.5 m → Table 8 @ 15 ft, 4.5 m → Table 10 @ 15 ft, 6.0 m → Table 10 @ 20 ft.
- Open-top containers (2.2.4): combustible open-top containers can be treated as closed-top only when all of them are on the bottom tier; otherwise in-rack sprinklers per 2.2.4.3. Where storage exceeds 3.0 m, for commodities above Class 3 the in-rack sprinklers go on maximum 3.0 m vertical increments with only a single pallet load above the top level.
- Single in-rack level with quick-response pendent ceiling sprinklers (2.3.6.5): cartoned plastics and uncartoned unexpanded plastics, ceilings up to 13.5 m; ceiling sprinklers minimum K14.0, the in-rack level within ½ to ⅔ of the storage height, 230 L/min from the most remote 8 in-rack sprinklers; for uncartoned unexpanded plastics the ceiling design is 12 @ 90 psi (6.2 bar) for K14.0 and 12 @ 63 psi (4.3 bar) for K16.8. Uncartoned expanded plastics are not in this option.
- Alternative in-rack designs (2.3.6.6, Table 16): at a 9.0 m vertical installation, cartoned expanded plastics K14.0 with 100 gpm (380 L/min) from the most remote sprinkler; uncartoned plastics K22.4 with 120 gpm (455 L/min); maximum vertical distance 30 ft (9.0 m) for cartoned expanded and uncartoned plastics. Hose 950 L/min, 60 min; in-rack and ceiling designed independently.
5. Retrofit design for uncartoned plastics (Section 2.3.6.7)
Uncartoned unexpanded and uncartoned expanded plastics cannot be adequately protected by a single line of in-rack sprinklers in: open-frame single-row racks wider than 0.9 m; open-frame double-row racks without horizontal barriers; double-row racks wider than 2.7 m with barriers; or where the commodity extends more than 75 mm beyond the barrier edge. In those cases the retrofit design applies:
- Wet-pipe systems only; racks must be open-frame; open-top containers only on the bottom tier.
- Sprinklers: FM Approved Storage (ceiling) sprinklers, standard-coverage, quick-response, pendent, minimum K22.4 (K320), 70 °C.
- Location: face sprinklers within 450 mm of the rack face or of the pallet edge protruding into the aisle; in single-row racks 0.9-1.8 m deep the existing sprinklers are removed (Figure 23); in double-row racks the existing longitudinal flue sprinklers stay (Figure 24).
- Design: 120 gpm (455 L/min) from the most remote face sprinkler; number of sprinklers per Table 17: 3 in single-row racks 0.9-1.8 m deep (4 for uncartoned expanded plastics), 4 in double-row racks ≤ 2.7 m (3 + 3 for expanded), 5 in 2.7-3.6 m racks (4 + 4 for expanded); existing in-rack sprinklers are not counted and no balancing with the ceiling is needed.
- Hose 950 L/min (at least 380 L/min for inside hose), duration at least 60 min. Ceiling design per Table 13 with an IRAS(E) arrangement; where existing ceiling sprinklers are K5.6 (K80) or K8.0 (K115), or the ceiling design cannot be met, the face sprinklers are also installed above the top of storage.
6. Plastic pallets and containers
Section 2.2.5: use noncombustible or metal pallets whenever possible; include the combustibility of pallets in the overall commodity classification per DS 8-1; protect idle pallets per DS 8-24, which treats non-FM-Approved plastic pallets as uncartoned unexpanded plastic commodity and refers them to DS 8-9. For combustible open-top containers (totes, crates) stored in racks, Section 2.2.4 and Figure 3 open the in-rack route; noncombustible open-top containers are treated as closed-top when everything below them is noncombustible or they are on the bottom tier.
Field note: for plastics the two decisive questions are "is there a carton" and "is it foam". In the same rack under a 9.0 m ceiling, cartoned unexpanded plastics need K25.2 at 9 @ 1.4 bar (Table 8), uncartoned unexpanded plastics 10 @ 2.8 bar (Table 10) and uncartoned expanded plastics 12 @ 2.8 bar (Table 11), while the in-rack vertical increment drops from 4.5 m to 3.0 m. A product later stripped of its packaging or stacked bare instead of film-wrapped moves to another table in DS 8-9; the sprinkler design cannot be considered fixed until the class is re-assigned with DS 8-1.
Quick checklist
- Plastic class assigned per DS 8-1: cartoned/uncartoned, expanded/unexpanded; the most severe hazard in the area governs (2.2.2.2)
- Storage above 1.8 m → DS 8-9, below → DS 3-26 (Section 1.0)
- Correct table chosen: 3-6 for solid-piled storage, 8-11 for open-frame racks; no interpolation
- Ceiling over 12.2 m: Table 17b only for cartoned unexpanded plastics; in-rack sprinklers or a false ceiling for the others
- If in-rack sprinklers are needed: 4.5 / 3.0 m increments (Figure 15), 8/14 sprinklers @ 115 L/min (Table 12), ceiling per Table 13
- Uncartoned plastic retrofit cases (2.3.6.7) checked: minimum K22.4, 455 L/min, Table 17
- Plastic pallet and open-top container effects (2.2.4, 2.2.5, DS 8-24) reflected in the class and the in-rack decision
- Hose demand and duration per Table 14; clearance below the deflector 0.9 m (standard) / 1.5 m (EC)
Frequently Asked Questions
How does FM DS 8-9 classify plastics?
Section 2.2.2.2 ranks the hazards from lowest to highest as Class 1, 2, 3, 4, cartoned unexpanded plastic, cartoned expanded plastic, uncartoned unexpanded plastic and uncartoned expanded plastic. Protection options for plastics no longer take Group type into account, only expanded/unexpanded and cartoned/uncartoned; the class is assigned per DS 8-1.
From what storage height is plastic storage covered by DS 8-9?
Section 1.0: where Class 4 or plastic commodities are stored higher than 1.8 m; up to 1.8 m the storage is low-piled and is protected per DS 3-26. For Class 1-3 the threshold is 3.0 m.
What is the in-rack sprinkler vertical increment for plastic storage?
Figure 15: in open-frame racks 6.0 m below cartoned unexpanded plastics, 4.5 m below cartoned expanded plastics (cartoned unexpanded), 3.0 m for cartoned expanded and uncartoned plastics; a maximum of 3.0 m of storage above the top level. Per Table 12 the in-rack design is 8 or 14 sprinklers at a minimum of 115 L/min per sprinkler.
Can uncartoned plastics be protected with ceiling-only sprinklers above a 12.2 m ceiling?
No. Section 2.3.6.9.4: Table 17b applies only to Class 1-4 and cartoned unexpanded plastics. For solid-piled and palletized storage Section 2.3.6.9.5 gives an exception: maximum 7.6 m storage, 13.7 m ceiling, commodities up to uncartoned unexpanded plastics, wet system, quick-response 70 °C minimum K25.2 pendent, 12 @ 60 psi (4.1 bar).
How are plastic pallets treated?
Section 2.2.5: noncombustible or metal pallets whenever possible; the combustibility of pallets is included in the commodity class per DS 8-1; idle pallet storage is protected per DS 8-24, which treats non-FM-Approved plastic pallets as uncartoned unexpanded plastics and refers them to DS 8-9.
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: Section 1.0 (p.5), 2.2.2 (p.10), 2.2.4 (p.23-26), 2.2.5 (p.26), 2.3.3.7 (p.29-31), Tables 3-6 (p.33-35), Tables 8-11 (p.37-39), 2.3.3.7.3 (p.40), 2.3.4.7 and Figure 15 (p.55-56), Tables 12-13 (p.57-58), 2.3.6.5 (p.67-68), 2.3.6.6 and Table 16 (p.68-71), 2.3.6.7 and Table 17 (p.72-76), 2.3.6.9 and Table 17b (p.79-80), Appendix B (p.99)
- FM Global data sheets: fmglobal.com; related sheets DS 8-1 (commodity classification), DS 8-24 (idle pallets), DS 3-26 (low-piled storage)
Values 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.