EN 12845 Annex G: Sprinkler Protection of Aerosol Product Storage

Aerosol storage is a separate topic in sprinkler design and is dealt with inside the annex "protection of special hazards", Annex G (normative, EN p.145-152) of TS EN 12845+A2:2026 (EN 12845:2015+A2:2026). The part of that annex devoted to aerosols is short: Clause G.2, two sentences, a NOTE and Table G.1. This article reproduces that part as it stands, fills no gaps, and shows where the subject begins and ends in the standard.

1. The structure of Annex G

Clause G.1 General (EN p.145): "The additional requirements of this annex shall be used for the protection of the products stated."

The sub-headings and numbers of the annex are as follows (Contents, EN p.8-9):

Aerosols are in G.2; G.4 is flammable liquid storage and is a different subject.

2. All that the standard says about aerosols in this annex

Clause G.2 Aerosols (EN p.145) reads in full:

Where aerosol products are separated from other product types and are contained in cages, the following protection design (see Table G.1) shall be used.

NOTE: Where such products are not contained in cages, sprinkler protection may not be effective.

The only additional sentence of the clause, below the table, is this: in-rack sprinklers shall be of the quick response type and their temperature shall comply with 14.4.

That is the whole of what the standard says about aerosols. There is no grading of aerosols, no barrier wall, no in-rack spacing, no ESFR alternative and no classification method based on the safety data sheet in this annex.

3. Table G.1: Protection criteria for aerosol storage (EN p.145)

Four points to note when reading the table:

1. The classification has two groups: alcohol based and hydrocarbon based. No other grading of aerosols appears in the text of the standard.
2. The height limit is very low: a maximum storage height of 1.5 m in ST1 and a tier height of not more than 1.8 m in ST4.
3. The ceiling sprinkler temperature is 141 °C in all rows; this is one of the table's own columns.
4. In-rack sprinklers are mandatory in the ST4 rows ("plus in-rack sprinklers").

The definitions of the storage configurations are in Clause 6.3.2 (EN p.33): ST1 free standing or block stacking; ST4 palletized racking (beam pallet racking).

4. How the design values connect to the other clauses

Table G.1 gives only the density and the area; the rest of the system comes from the body clauses.

• Sprinkler temperature (Clause 14.4, EN p.105): sprinklers shall be selected with a temperature rating close to, but not lower than, 30 °C above the highest expected ambient temperature. In unventilated concealed spaces, beneath skylights or glazed roofs and so on, it may be necessary to install sprinklers with a higher operating temperature, up to 93 °C or 100 °C. Table 37b (EN p.105) gives the colour code: 141 °C in a glass bulb is blue; on fusible link sprinklers the range 121 °C - 149 °C is blue on the yoke arms.
• Water supply duration (Clause 8.1.1, EN p.42): 90 min for HHS, 90 min for HHP, 60 min for OH and 30 min for LH.
• Minimum discharge pressure (Clause 13.4.4, EN p.102): 0.50 bar for HHP and HHS (excluding in-rack sprinklers); 1.00 bar for K115 in-rack sprinklers; 2.00 bar for K80 in-rack sprinklers.
• k-factor (Table 37a, EN p.104): where the design density for HHP and HHS ceiling sprinklers exceeds 10 mm/min, K115 or K160 shall be used. Both density values in Table G.1 (12.5 and 25.0 mm/min) are above that threshold.
• Coverage area (Table 19, Clause 12.2, EN p.70): in HHP and HHS the maximum area per sprinkler is 9.0 m² and the maximum spacing 3.7 m.
• Clear distance below the deflector (Clause 12.1.2, EN p.70): 1.0 m for HHP and HHS.
• Minimum water volume in pre-calculated systems (Table 10, Clause 9.3.2.2, EN p.48): where the design density does not exceed 12.5 mm/min, 350 m³ in a wet system and 440 m³ in a dry system; where it does not exceed 25.0 mm/min, 725 m³ in a wet system and 905 m³ in a dry system.
• In-rack hydraulic calculation (Clause 7.2.3.3, EN p.37): for the purposes of hydraulic calculation, 3 sprinklers at the hydraulically most remote position at each in-rack sprinkler level shall be assumed to operate simultaneously, up to a maximum of three levels. Where the rack aisles are 2.4 m or wider, only one rack is assumed to be affected; where they are between 1.2 m and 2.4 m, two racks; where they are narrower than 1.2 m, three racks. The NOTE to Clause 7.2.3.4: the minimum pressure at any operating sprinkler is 2.0 bar (see 13.4.4).
• Limit on the number of in-rack sprinklers (Clause 7.2.3.1, EN p.37): where more than 50 intermediate level sprinklers are installed in racks, they shall not be fed from the same control valve set as the roof or ceiling sprinklers.

The order of magnitude of the ceiling demand can be derived directly from the values in Table G.1: for alcohol based aerosols 12.5 mm/min × 260 m² = 3 250 l/min, and for hydrocarbon based aerosols 25.0 mm/min × 300 m² = 7 500 l/min (this is only the product of density and area; pipe friction losses and the in-rack demand are added to it separately).

5. Aerosols are not within the scope of EN 12845-2

This point should be underlined: Clause 6.1 (EN p.33) of TS EN 12845-2:2025 (EN 12845-2:2024) states:

The storage of goods not covered by the design tables (for example flammable liquids, aerosols and single pallet loads of such goods) shall not be protected in accordance with this document; instead, EN 12845 shall be applied where applicable.

In other words, an aerosol warehouse cannot be designed with ESFR or CMSA; the protection is built with the CMDA approach of EN 12845 and with Annex G.

6. The neighbouring clauses of Annex G

Two neighbouring clauses are often confused when designing for aerosols:

• G.4 Flammable liquid storage (EN p.147-149): flammable liquids are divided into four classes according to their flash point (FP) and boiling point (BP) and are protected by Tables G.2, G.3 and G.4. Example: Table G.2 (in metal drums, volume >20 l and <208 l, ST1) for Class 1 with FP ≥ 100 °C, on-side up to a height of 12 drums, 10 mm/min and 450 m²; for Classes 2, 3 and 4, 25 mm/min and 450 m².
• G.5 Idle pallets (EN p.149): idle pallets stored in solid piles or on pallets shall be protected by ceiling sprinklers in accordance with Table G.5; pallets stored in racks shall be protected by ceiling and in-rack sprinklers in accordance with Table G.6. Table G.5: for pallets of timber and cellulosic material, the maximum permitted storage height is 3.8 m and the ceiling sprinklers are as for Category IV (see Table 4); for plastic pallets, 3.3 m and 25 mm/min over 300 m², with storage in a 60 min fire resisting compartment as a special requirement.

Field note: The aerosol part of Annex G defines a narrow protection window with its cage requirement and its 1.5 m and 1.8 m height limits. An aerosol warehouse that falls outside that window cannot be solved with the design criteria given by the standard and requires a separate assessment.

Frequently Asked Questions

Which design values does EN 12845 give for aerosol storage?

TS EN 12845+A2:2026 Table G.1, Clause G.2, EN p.145: in ST1 free standing and block storage the maximum storage height is 1.5 m; 12.5 mm/min density and 260 m² area of operation for alcohol based aerosols, 25.0 mm/min and 300 m² for hydrocarbon based aerosols. In ST4 palletized rack tiers the tier height is not more than 1.8 m; 12.5 mm/min plus in-rack sprinklers and 260 m² for alcohol based, 25.0 mm/min plus in-rack sprinklers and 300 m² for hydrocarbon based. The ceiling sprinkler temperature is 141 °C in all rows.

On what precondition does aerosol protection depend?

Clause G.2, EN p.145: the protection design in Table G.1 shall be used where aerosol products are separated from other product types and are contained in cages. NOTE: where such products are not contained in cages, sprinkler protection may not be effective.

How does EN 12845 classify aerosols?

Table G.1, EN p.145 deals with aerosols in two groups: alcohol based and hydrocarbon based. There is no other grading of aerosols in the text of the standard.

How are in-rack sprinklers selected in aerosol storage?

Clause G.2, EN p.145: in-rack sprinklers shall be of the quick response type and their temperature shall comply with 14.4. Clause 14.4, EN p.105: sprinklers shall be selected with a temperature rating close to, but not lower than, 30 °C above the highest expected ambient temperature.

Can aerosols be protected under EN 12845-2 (ESFR and CMSA)?

No. TS EN 12845-2:2025 Clause 6.1, EN p.33: the storage of goods not covered by the design tables, for example flammable liquids, aerosols and single pallet loads of such goods, shall not be protected in accordance with this document; instead EN 12845 shall be applied where applicable.

References

• TS EN 12845+A2:2026 (EN 12845:2015+A2:2026), Contents - sub-headings of Annex G (EN p.8-9)
• TS EN 12845+A2:2026, Clause 6.3.2 Storage configuration (EN p.33)
• TS EN 12845+A2:2026, Clauses 7.2.3.1, 7.2.3.3 and the NOTE to 7.2.3.4 (EN p.37)
• TS EN 12845+A2:2026, Clause 8.1.1 (EN p.42)
• TS EN 12845+A2:2026, Clause 9.3.2.2 and Table 10 (EN p.48)
• TS EN 12845+A2:2026, Clause 12.1.2 and Table 19 (EN p.70)
• TS EN 12845+A2:2026, Clause 13.4.4 (EN p.102)
• TS EN 12845+A2:2026, Table 37a (EN p.104)
• TS EN 12845+A2:2026, Clause 14.4 and Table 37b (EN p.105)
• TS EN 12845+A2:2026, Annex G, Clauses G.1, G.2 and Table G.1 (EN p.145)
• TS EN 12845+A2:2026, Clause G.4 and Table G.2 (EN p.147-148)
• TS EN 12845+A2:2026, Clause G.5 and Table G.5 (EN p.149), Table G.6 (EN p.150)
• TS EN 12845-2:2025 (EN 12845-2:2024), Clause 6.1 (EN p.33)

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