Short answer: TS EN 12845+A2:2026 Clause G.4 (EN p.147): flammable liquids are divided into four classes according to their flash point (FP) and boiling point (BP). According to Table G.2 (EN p.148) Class 1: FP >= 100 °C; Class 2: FP < 100 °C; Class 3: FP < 35 °C; Class 4: FP < 21 °C and BP < 35 °C.

Source: TS EN 12845+A2:2026, Clause G.4 "Flammable liquid storage" (EN p.147), Table G.2 and Table G.3 (EN p.148), Table G.4 (EN p.149).

Clause G.4 consists of a short introductory sentence and three tables. The whole design is read from those tables; in this clause the standard gives no provision on the extinguishing method, foam, spill control or detection.

The text of Clause G.4

Clause G.4 (EN p.147) is a single sentence: "Flammable liquids shall be classified into four classes according to their flash point (FP) and boiling point (BP), as shown in Tables G.2, G.3 and G.4."

Classification

Class Properties (°C)
1 FP >= 100
2 FP < 100
3 FP < 35
4 FP < 21 and BP < 35

Source: Table G.2, EN p.148.

Note carefully: in this system Class 1 is the least flammable and Class 4 the most flammable. As the class number rises, the flash point falls and the design becomes more onerous.

Table G.2: ST1 metal drums, capacity > 20 l and <= 208 l

Class Properties (°C) Drum orientation Permitted storage Ceiling sprinkler density (mm/min) Area of operation (m2)
1 FP >= 100 On side <= 12 drums high 10 450
1 FP >= 100 On end <= 6 drums high 10 450
2 FP < 100 On side <= 6 drums high 25 450
2 FP < 100 On end <= 2 drums high 25 450
3 FP < 35 On side <= 3 drums high 25 450
3 FP < 35 On end <= 1 drum high 25 450
4 FP < 21 and BP < 35 On side or on end 1 drum high 25 450

Source: Table G.2, EN p.148.

In this table the storage limit is given not in metres but as a number of drums. The drum orientation (on side / on end) directly changes the permitted number.

Table G.3: ST4 palletized racks, metal drums, capacity > 20 l and <= 208 l

Class Properties (°C) Drum orientation Intermediate sprinkler levels Ceiling density (mm/min) Area of operation (m2)
1 FP >= 100 On side Each 12th tier 10 450
1 FP >= 100 On end Each 6th tier 10 450
2 FP < 100 On side Each 6th tier 25 450
2 FP < 100 On end Each tier 10 450
3 FP < 35 On side Each 3rd tier 25 450
3 FP < 35 On end Each tier 10 450
4 FP < 21 and BP < 35 On side or on end Each tier 25 450

NOTE (EN p.148): This table applies to drums stored at a height of one drum per tier.

Source: Table G.3, EN p.148.

The logic of Table G.3 is this: in on-end storage the intermediate sprinkler levels become more frequent while the ceiling density drops (10 mm/min for Classes 2 and 3), whereas in on-side storage the intermediate levels become sparser and the ceiling density rises to 25 mm/min.

Table G.4: ST1, ST5, ST6 metal drums, capacity <= 20 l

Class Properties (°C) Type of storage Maximum permitted storage height (m) Ceiling density (mm/min) Area of operation (m2)
1 FP >= 100 ST1 5.5 10 450
1 FP >= 100 ST5/6 4.6 7.5 450
2 FP < 100 ST1 4.0 12.5 450
2 FP < 100 ST5/6 4.6 12.5 450
3 FP < 35 ST1 1.5 12.5 450
4 FP < 21 and BP < 35 ST5/6 2.1 12.5 450

Source: Table G.4, EN p.149. (In Class 2 the density cell spans the ST1 and ST5/6 rows together.)

Table G.4 covers only ST1, ST5 and ST6 (title: metal drums with a capacity up to 20 l, EN p.149); the table has no ST1 row for Class 4 and no ST5/6 row for Class 3, and the standard regulates only the combinations listed.

Comparison of the three tables

Item Table G.2 Table G.3 Table G.4
Container type Metal drum > 20 l, <= 208 l Metal drum > 20 l, <= 208 l Metal drum <= 20 l
Storage configuration ST1 ST4 ST1, ST5, ST6
Unit of the limit Number of drums Number of tiers (intermediate sprinkler frequency) Metres
Density range 10 or 25 mm/min 10 or 25 mm/min 7.5; 10; 12.5 mm/min
Area of operation 450 m² 450 m² 450 m²

Source: Tables G.2, G.3 (EN p.148) and Table G.4 (EN p.149).

What the three tables have in common is the 450 m² area of operation; this is markedly larger than the 260 m² and 300 m² values the standard uses for HHS storage (Table 4, EN p.38).

Clause G.4 gives no provision for duration; the general provision is in Clause 8.1.1 (EN p.42): LH 30 min, OH 60 min, HHP 90 min, HHS 90 min.

What the standard does not say here

Field note

Field note (not from the standard, this is engineering interpretation): in this clause the input that fixes the design is not the commercial name of the product but the measured flash and boiling point, so the FP/BP values from the safety data sheet of every stored product have to go into the project file. A change of drum orientation (on side / on end) during operation means, under Tables G.2 and G.3, a direct change of design.

Frequently Asked Questions

How does EN 12845 classify flammable liquids?

TS EN 12845+A2:2026 Clause G.4 (EN p.147): flammable liquids are divided into four classes according to their flash point (FP) and boiling point (BP). According to Table G.2 (EN p.148) Class 1: FP >= 100 °C; Class 2: FP < 100 °C; Class 3: FP < 35 °C; Class 4: FP < 21 °C and BP < 35 °C.

How large is the area of operation?

In Tables G.2, G.3 and G.4 alike (EN p.148-149) the area of operation is 450 m² for every class. The ceiling densities take the values 7.5, 10, 12.5 and 25 mm/min.

How is the stack height of metal drums limited?

Table G.2 (EN p.148), for ST1 metal drums with a capacity > 20 l and <= 208 l: Class 1 on side <= 12 drums, on end <= 6 drums; Class 2 on side <= 6, on end <= 2; Class 3 on side <= 3, on end <= 1; Class 4 on side or on end 1 drum high. The ceiling density is 10 mm/min for Class 1 and 25 mm/min for Classes 2, 3 and 4.

What is the intermediate sprinkler frequency in rack storage of drums?

Table G.3 (EN p.148, ST4): Class 1 on side each 12th tier, on end each 6th tier, density 10 mm/min; Class 2 on side each 6th tier at 25 mm/min, on end each tier at 10 mm/min; Class 3 on side each 3rd tier at 25 mm/min, on end each tier at 10 mm/min; Class 4 each tier at 25 mm/min. In all cases the area is 450 m². NOTE: this table applies to drums stored at a height of one drum per tier.

Does EN 12845 require foam or a bund in flammable liquid storage?

Clause G.4 contains no provision on foam, deluge valves, proportioners or bunds/dykes. In Annex G a foam additive is required only in Clause G.8.5 (EN p.152) for PP/PE bins, while drainage or a bund appears only in Clause G.6 (EN p.150) at the level of a recommendation.

References

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Standards & References

TS EN 12845+A2:2026 (EN 12845:2015+A2:2026) Fixed firefighting systems — Automatic sprinkler systems — Design, installation and maintenance; TS EN 12845-2:2025 (EN 12845-2:2024) ESFR and CMSA sprinkler systems. Every figure in this article is taken from the published standard text; clause, table and page references are listed under References. General information only, not a substitute for the standard or for a design review.