Short Answer
FM DS 8-24 Idle Pallet Storage deals with the storage of empty wood, plastic and FM Approved pallets. Its main preference is outdoor storage, and protection splits by pallet type: a non-FM Approved plastic pallet is treated directly as a UUP commodity and sent to DS 8-9, while wood and FM Approved pallets use the data sheet's own protection table.
Identity and Scope of the Data Sheet
The copy used here is dated January 2013, with a January 2015 interim revision, and has 6 pages (cover, PDF p.1). Under the scope section (Section 1.0), the data sheet gives protection recommendations to minimize exposure to fire, water and smoke damage in the storage of idle wood, plastic and FM Approved pallets (PDF p.2). For the general framework of commodity classification see the DS 8-1 commodity classification article, and for the EN side the EN 12845 Annex G idle pallet storage article.
Appendix A defines the pallet terms clearly (PDF p.5): a wood pallet covers all pallets of wood and cellulosic material with slatted or solid top and bottom decks; a plastic pallet is any plastic pallet with a solid or grid deck, and FM Approved plastic pallets are not part of this group; an FM Approved plastic pallet is one found by fire testing to be equivalent to a wood pallet. A slave pallet is usually flat plywood under 20 ft2 (2.0 m2), and when stacked idle the arrangement resembles a solid wood pile (Class 3 commodity).
Outdoors: Separation Distances
Section 2.1.1.1 states that outdoor storage is preferred and that FM Approved plastic pallets can be stored in the same places as wood pallets (PDF p.2). Table 1 gives separation distances by exposed wall category and number of pallets (DS 8-24, Table 1, PDF p.2).
| Wall category | ≤50 pallets, wood and FM Approved | ≤50 pallets, plastic | 51-200 pallets, wood and FM Approved | 51-200 pallets, plastic | >200 pallets, wood and FM Approved | >200 pallets, plastic |
|---|---|---|---|---|---|---|
| Combustible | 15 ft (4.5 m) | 30 ft (9 m) | 40 ft (12 m) | 80 ft (24 m) | 90 ft (27 m) | 150 ft (45 m) |
| Noncombustible | 12 ft (3.7 m) | 15 ft (4.5 m) | 30 ft (9 m) | 40 ft (12 m) | 50 ft (15 m) | 100 ft (30 m) |
| 1 hour | 4 ft (1.2 m) | 8 ft (2.4 m) | 12 ft (3.7 m) | 24 ft (7.4 m) | 20 ft (6 m) | 40 ft (12 m) |
| 2 hours | 3 ft (1 m) | 6 ft (2 m) | 10 ft (3 m) | 20 ft (6 m) | 15 ft (4.5 m) | 30 ft (9 m) |
| 3 hours | 3 ft (1 m) | 3 ft (1 m) | 8 ft (2.5 m) | 16 ft (5 m) | 13 ft (4 m) | 26 ft (8 m) |
| 4 hours | 3 ft (1 m) | 3 ft (1 m) | 3 ft (1 m) | 3 ft (1 m) | 3 ft (1 m) | 3 ft (1 m) |
The table note adds that the 3 ft (1 m) distance at a 4-hour wall is for access only. Table 2 gives safe separation distances between pallet piles standing side by side outdoors and uses the same values as the combustible wall row of Table 1: for ≤50 pallets, 15 ft (4.5 m) for wood and FM Approved and 30 ft (9 m) for plastic; for 51-200 pallets, 40 ft (12 m) and 80 ft (24 m); above 200, 90 ft (27 m) and 150 ft (45 m) (DS 8-24, Table 2, PDF p.2).
Where the two tables must be read together: for the same number of pallets, the distance for plastic pallets is twice that for wood, and the distance drops quickly as the fire resistance of the wall increases. The general framework of exterior exposure is covered in the neighbouring building exposure article.
Section 2.1.1.2 also requires pile height to be limited, where pallets are stored near a building, so that burning pallets cannot fall onto the building (PDF p.2).
Indoors and Pallets in Production Areas
Section 2.1.2.1 defines the indoor arrangements as solid-piled, single-row, double-row or multiple-row racks, and the small quantities of pallets needed for production (PDF p.2).
For production areas, Section 2.1.3.1 sets two limits if the sprinkler protection does not meet the recommendations of Section 2.2 (PDF p.3):
- A. A single stack height of no more than 5 ft (1.5 m) for plastic, wood and FM Approved pallets; the exception applies where the ceiling protection of the storage area meets this data sheet's recommendations for higher levels.
- B. At least 10 ft (3.0 m) between single pallet stacks and other pallet stacks, combustible material or equipment.
Protection by Pallet Type
Section 2.2.1.3 gives the basic rule: the protection of a storage area is set by the most demanding pallet type in that area; if the area holds other commodities or more hazardous materials, protection is chosen for the item requiring the most protection (PDF p.3). Section 2.2.1.1 states that building column and overhead steel protection is not needed if the other protection rules of this data sheet are met.
| Pallet type | DS 8-24 direction | Reference |
|---|---|---|
| Non-FM Approved plastic pallet | Treated as uncartoned unexpanded plastic (UUP) commodity, protected per DS 8-9 | Section 2.2.2.1, PDF p.3 |
| Pallet of expanded plastic | Protected per the DS 8-9 recommendations for that commodity | Section 2.2.2.1, PDF p.3 |
| Wood and FM Approved pallets, solid-piled on the floor | Protected per the design guidance in Table 3 | Section 2.2.3.1.1, PDF p.3 |
| Wood pallets, in racks | The K14.0 (K200) quick-response pendent option in Table 3 applies | Section 2.2.3.2.1.1, PDF p.4 |
| Metal pallets, indoors | Sprinkler protection as required by the occupancy | Section 2.2.4.1, PDF p.4 |
The route to DS 8-9 is the most critical decision in this data sheet: a non-approved plastic pallet is protected not by a separate pallet rule but directly by the plastic commodity rules. The plastic commodity side is covered in the DS 8-9 plastics storage article. Section 2.2.2.2 also requires that, where in-rack sprinklers are needed per DS 8-9, only those in-rack designs for UUP protection that require the use of horizontal barriers are chosen (PDF p.3).
Table 3 and Hose Allowance
For solid-piled floor storage of wood and FM Approved pallets, Table 3 gives the number of sprinklers and minimum operating pressure by ceiling and storage height (DS 8-24, Table 3, PDF p.4). Sample rows: for a 15 ft (4.5 m) ceiling and 10 ft (3.0 m) storage, wet system, 160°F (70°C), quick-response K14.0 (K200) pendent sprinklers, 12 sprinklers @ 50 psi (3.5 bar); in the same row, standard-response K11.2 (K160) upright sprinklers at 15 sprinklers @ 25 psi (1.7 bar), and for a dry system with 280°F (140°C) standard-response K11.2, 25 sprinklers @ 25 psi (1.7 bar). In the K14.0 (K200) column the table extends to a 40 ft (12.0 m) ceiling and 35 ft (10.5 m) storage; the 35 ft (10.5 m) ceiling/30 ft (9.0 m) storage and 40 ft (12.0 m) ceiling/35 ft (10.5 m) storage rows give 12 sprinklers @ 75 psi (5.2 bar).
Hose allowance and duration depend on the sprinkler chosen:
| Sprinkler | Hose flow | Duration | Reference |
|---|---|---|---|
| K11.2 (K160) | 500 gpm (1900 L/min) | 90 minutes | Section 2.2.3.1.2, PDF p.3 |
| K14.0 (K200) | 250 gpm (950 L/min) | 60 minutes | Section 2.2.3.1.3, PDF p.3 |
Sections 2.2.3.1.4 and 2.2.3.2.1.3 require protection per Section 2.2.2, that is the DS 8-9 route, for storage or ceiling heights higher than those shown in Table 3, or for larger K-factor options not in the table (PDF p.4). For K-factor families see the site's K-factor table.
The clearance definition in Appendix A also binds the design: at least 3 ft (0.9 m) of clearance is needed for all ceiling-level sprinklers; for in-rack sprinklers the deflector must be at least 6 in. (150 mm) above the top of storage (PDF p.5).
Loss History
Section 3.1 reviews FM's idle pallet storage losses for 2002-2012 (PDF p.4):
- 91% of losses involved idle wood pallet storage and the remaining 9% plastic pallets.
- 65% of losses occurred in storage outside the building.
- Sprinkler protection was reported effective in 57% of indoor fires; the average dollar loss in adequately protected pallet storage stayed at about 12% of that in fires with no or ineffective protection.
Section 3.0 also states that tests have shown the DS 8-9 UUP protection recommendations to give adequate protection for idle plastic pallet storage, and that FM has run full-scale rack and solid-pile fire tests with plastic pallets (PDF p.4).
Field Note
Two points are most often missed when reading this data sheet. The first is that outdoor distances depend on the number of pallets: on a yard working with 50 pallets, 15 ft (4.5 m) to a combustible wall is enough, but when the same yard goes above 200 pallets the distance jumps to 90 ft (27 m) (Table 1, PDF p.2). In facilities where the pallet stock grows seasonally, the distance should be checked not at the initial layout but in the peak season.
The second is the "we bought plastic pallets, we'll put them in the same place" approach. Under Section 2.2.2.1 a non-FM Approved plastic pallet is not a pallet but a plastic commodity, and its protection comes from DS 8-9 (PDF p.3). An FM Approved plastic pallet, under the Appendix A definition, is accepted as equivalent to a wood pallet. The purchasing decision therefore changes the sprinkler design directly; a plastic pallet without an approval record can leave the existing ceiling protection inadequate.
Checklist
- Pallet types on site counted separately: wood, plastic, FM Approved plastic, metal, slave pallets
- Any claim of FM Approved plastic pallets confirmed with the approval record
- For outdoor piles, wall category and pallet count determined and the Table 1 distance applied
- Table 2 distances provided between side-by-side piles
- Height of piles near the building limited for the risk of falling (Section 2.1.1.2)
- Stacks in production areas arranged to the 5 ft (1.5 m) and 10 ft (3.0 m) limits
- Storage area protection chosen for the most demanding pallet type in the area (Section 2.2.1.3)
- If ceiling and storage height fall outside the Table 3 range, protection built via DS 8-9
- Hose allowance and duration taken correctly for the chosen sprinkler (500 gpm/90 min or 250 gpm/60 min)
- 3 ft (0.9 m) clearance for ceiling sprinklers and 6 in. (150 mm) for in-rack sprinklers provided
Frequently Asked Questions
Where does FM DS 8-24 prefer idle pallets to be stored?
Outdoors. Section 2.1.1.1 states that outdoor storage is preferred and asks for the separation distances in Table 1 to be applied. Section 2.1.1.2 also requires pile height to be limited, where pallets are stored near a building, so that burning pallets cannot fall onto the building.
Which commodity class is a non-FM Approved plastic pallet?
Under Section 2.2.2.1, plastic pallets that are not FM Approved are classified as uncartoned unexpanded plastic (UUP) and protected per DS 8-9. This covers 2-way, 4-way, solid-deck and composite pallets; pallets made of expanded plastic are protected according to their own commodity group in DS 8-9.
How high can pallets be stacked in a production area?
If the sprinkler protection does not meet the recommendations of Section 2.2, Section 2.1.3.1 limits single stacks of plastic, wood and FM Approved pallets to a height of 5 ft (1.5 m), and at least 10 ft (3.0 m) is kept between the stacks and other pallet stacks, combustible material or equipment.
What does the loss history of idle pallet fires show?
According to the 2002-2012 review in DS 8-24 Section 3.1, 91% of losses involved wood pallet storage and 9% plastic pallet storage; 65% occurred in storage outside the building. Sprinkler protection was found effective in 57% of indoor fires, and the average dollar loss in adequately protected storage stayed at about 12% of that in fires with no or ineffective protection.
References
- FM Property Loss Prevention Data Sheet 8-24, Idle Pallet Storage, January 2013, Interim Revision January 2015. Sections used: Section 1.0 (PDF p.2), 2.1.1.1-2.1.1.3 and Table 1 (p.2), Table 2 and 2.1.2.1 (p.2-3), 2.1.3.1 (p.3), 2.2.1.1-2.2.1.3 (p.3), 2.2.2.1-2.2.2.2 (p.3), 2.2.3.1.2-2.2.3.1.3 (p.3), Table 3 and 2.2.3.2 (p.4), 2.2.4.1 (p.4), 3.0-3.1 (p.4), Appendix A (p.5).
- FM Global, Property Loss Prevention Data Sheets: https://www.fmglobal.com/research-and-resources/fm-global-data-sheets
- selvi.org, FM Global DS 8-1: Commodity Classification
- selvi.org, EN 12845 Annex G: Idle Pallet Storage
- selvi.org, DS 8-9: Class 1-4 and Plastic Storage
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Download MEP Calc on the App StoreFM Property Loss Prevention Data Sheet 8-24, Idle Pallet Storage, January 2013, Interim Revision January 2015; clause, table and page references are listed under References. General information only: the current edition governs, and design must be carried out by a qualified engineer.