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.

FS

Fatih Selvi

Mechanical engineer and software developer with field experience in MEP and fire protection, working actively with NFPA, FM Global and BS EN 12845 on site projects.