EN 12845-2:2024 Overview: ESFR and CMSA

TS EN 12845-2:2025 is the identical counterpart of EN 12845-2:2024; it was prepared by CEN/TC 191, approved by CEN on 11.11.2024 and adopted as a Turkish Standard at the meeting of the Technical Board of the Turkish Standards Institution on 22.12.2025 (National Foreword). The European foreword (EN p.3) states that this European Standard shall be given the status of a national standard by June 2025 at the latest and that conflicting national standards shall be withdrawn by June 2025 at the latest.

This article summarises the structure and scope of the standard and its relationship with EN 12845-1 from the text alone.

1. Scope

Clause 1 (EN p.5): This document specifies the requirements for the design and installation of early suppression fast response (ESFR) and control mode specific application (CMSA) sprinklers in automatic sprinkler systems, in accordance with this standard and in addition with the standards of the EN 12845 series. The document does not cover all regulatory requirements; a NOTE points out that specific national regulations may apply in some countries.

2. The skeleton of the standard

The contents (EN p.2) end the structure with a single annex:

The only annex of the standard is Annex A. There are no separate annexes on water supplies, pumps, commissioning or maintenance.

3. Normative references (Clause 2, EN p.5)

• EN 12845:2015+A1:2019 - Fixed firefighting systems, automatic sprinkler systems, design, installation and maintenance
• EN 12845 (the whole series)
• EN 12259-1 - Sprinklers
• EN 12259-13 - ESFR sprinklers
• prEN 12259-15 - Spray pattern sprinklers with a k-factor of at least K160, extended coverage sprinklers of at least K80 and control mode special application sprinklers

4. Allocation of tasks: which subject is in which standard

Table 1 (Clause 4, EN p.7) shows the order of tasks and their source. EN 12845-2 sets requirements on its own in only four rows:

5. Clause 4: the basic rules

Clause 4 (EN p.6) contains four rules:

1. ESFR sprinklers shall be used in wet installations only.
2. CMSA sprinklers may be used in wet and dry installations.
3. Open-top containers shall not be used in storage hazards protected by ESFR or CMSA unless specifically stated otherwise in a clause of the standard. Open-top non-combustible containers may be treated as closed-top non-combustible containers where all the storage beneath them is non-combustible or in non-combustible containers, or where they are all on the bottom tier of the rack.
4. Annex A shall be applied for the determination of FH and HHS.

For unheated areas, Clause 6.5 (EN p.35) gives a separate rule: there is no dry installation option for this ESFR concept. Where dry pendent ESFR sprinklers are used, the installation is considered as a wet installation. Designs with propylene glycol may be applied provided that the k-factor is not less than 320, the premixed antifreeze solution does not exceed 30% glycol by volume and a tree type pipe layout is used. In the same K320 and larger systems, the glycol concentration may be increased to 40% by volume if it can be proved that water reaches a sprinkler within 60 s; after 60 s there shall be no more than 5% glycol by volume. The hydraulic calculation for the demand is carried out on a wet installation basis.

6. Clause 5: installation requirements

The four sub-clauses of Clause 5 establish an installation framework common to ESFR and CMSA:

• 5.1 Sprinkler type, spacing, clearance and nominal operating temperature (EN p.7-12): ESFR pendent, dry pendent or upright sprinklers to EN 12259-13; CMSA pendent, dry pendent or upright sprinklers to prEN 12259-15 (in dry CMSA systems only dry pendent and upright). ESFR spacing at least 2.4 m and at most 3.7 m (ceiling ≤9.1 m) or 3.1 m (ceiling >9.1 m), maximum 9.3 m² and minimum 6 m² per head. CMSA spacing at least 2.4 m and at most 3.7 m (3.1 m with combustible obstructed construction), maximum 12 m² (in certain STC1 cases) or 9.3 m² and minimum 7.5 m² per head. The deflector at least 100 mm below the ceiling; the maximum vertical distance is between 225 mm and 425 mm in Table 2, depending on the k-factor.
• 5.2 Construction and building limitations (EN p.12-21): maximum ceiling slope 10° (17.6%); ceilings shall withstand a vertical upward thrust of 140 N/m²; skylights shall withstand 300 °C for 5 min and those with a volume exceeding 1 m³ shall be protected; manually opened smoke and heat vents only; an air velocity limit of 1.5 m/s at ceiling level; quick response or ESFR sprinklers beneath solid mezzanines.
• 5.3 Obstruction to discharge pattern of sprinklers (EN p.21-32): Clause 5.3.1 states that the obstruction requirements are the same for ESFR and CMSA. Table 3 (EN p.23) gives the minimum horizontal distance to ceiling objects: 300 mm for an object 50 mm below the sprinkler deflector, 500 mm for 100 mm, 700 mm for 150 mm, 800 mm for 200 mm and 1 000 mm for 300 mm. Table 4 (EN p.24) and Table 5 (EN p.26) complete the rules for the inner core pattern and for obstructions above racks.
• 5.4 Additional requirements for the protection of HHS5 with a 12 sprinkler design (EN p.32-33): intermediate temperature rated (79 °C - 107 °C) ESFR pendent sprinklers, nominal K360; maximum deflector distance below the ceiling 350 mm; minimum aisle width 2.4 m; vertical barriers of 10 mm plywood/chipboard or 0.78 mm sheet steel at a maximum spacing of 5.0 m from rack face to rack face; a plan area between barriers and aisles of not more than 12 m². Minimum operating pressure: 2.0 bar for storage ≤7.6 m and ceiling ≤9.1 m, 4.1 bar for storage ≤10.7 m and ceiling ≤12.2 m.

7. Clause 6: the design tables

Example values: in ESFR Table 7 (EN p.36), HHS1-HHS3 for a 9.1 m ceiling / 7.6 m storage, K200 3.4 bar, K240 2.4 bar, K320 1.7 bar, K360 1.0 bar; in Table 11 (EN p.41), HHS1-HHS3 for a 16.8 m ceiling / 15.2 m storage, K400 9 sprinklers @ 5.5 bar or K480 9 sprinklers @ 3.8 bar. In the modular in-rack design, Table 14 (EN p.47) gives the minimum flow required from the most remote in-rack sprinkler: 250 l/min for K200 up to HHS3, 380 l/min for K200 up to HHS4 and 455 l/min for K320 up to HHS5.

8. Annex A and the link with EN 12845-1

Annex A (normative, EN p.59-60) consists of two parts: Figure A.1, taken from prEN 12845-1 and updated so as to give information on the assessment of the HHS classes, and Table A.1, which converts the EN 12845:2015 classes into the FH classes of this document (LH and OH1 → FH1; OH2 and OH3 → FH2; OH4 → FH3; HHP1 and HHP2 → FH4; HHP3 → FH5).

The link in the other direction is established by the two normative annexes of TS EN 12845+A2:2026:

• Annex N (normative, EN p.162), CMSA: for CMSA sprinkler systems, EN 12845-2 shall be applied together with this document. Because of the different hazard classification systems, Annex A of EN 12845-2:2024 shall be applied; either the conversion Table A.1 or the flow chart in Figure A.1 is used.
• Annex P (normative, EN p.164), ESFR: for ESFR sprinkler systems, EN 12845-2 shall be applied together with this document. For the water supply of ESFR sprinkler systems, the use of three 50% pump sets conforming to EN 17451 is recommended. The class conversion is made in the same way with Annex A of EN 12845-2:2024.

9. The standard's own warning

The Introduction (EN p.4) addresses the designer directly: all three approaches (ESFR, CMSA, CMDA) are designed to provide rapid and effective control of a fire, and the determination of the most appropriate option should be left to competent personnel; in every case, final extinguishment is expected to be carried out by the fire service. ESFR and CMSA sprinkler designs are less capable of coping with adverse design features and non-conformities (for example those arising from incorrect design or from changes in practice over time at the protected premises); the risk that design and installation deviations from this standard may lead to total system failure is emphasised.

The same section also announces a plan: an Amendment is intended to be published in order to align EN 12845:2015+A1:2019 with this document and to update the references made to the ESFR and CMSA requirements; Annex A of this document has been added to support that transition.

Frequently Asked Questions

What does EN 12845-2:2024 cover and how many parts does it have?

Clause 1 Scope, EN p.5: this document specifies the requirements for the design and installation of ESFR and CMSA sprinklers in automatic sprinkler systems, in accordance with this standard and in addition with the EN 12845 series. Contents (EN p.2): 1 Scope, 2 Normative references, 3 Terms, definitions, symbols and abbreviated terms, 4 General, 5 Installation requirements, 6 Design considerations, and the single annex, Annex A (normative).

Does EN 12845-2 cover water supplies, pumps and maintenance?

No. Table 1, EN p.7: the type of water supply (Clause 9), pumps (Clause 10), valves (Clause 15), pipework (Clause 17), alarms (Clause 16), commissioning and initial inspection (Clause 19) and maintenance and inspection (Clause 20) are left to EN 12845:2015+A1:2019. EN 12845-2 itself governs only the spacing and location of sprinklers (5.1.3, 5.2, 5.3), obstructions (5.3) and the water supply duration and shape of design (6.4).

What are the normative references of EN 12845-2?

Clause 2, EN p.5: EN 12845:2015+A1:2019; the EN 12845 series; EN 12259-1 (sprinklers); EN 12259-13 (ESFR sprinklers); prEN 12259-15 (spray pattern sprinklers of at least K160, extended coverage sprinklers of at least K80 and CMSA sprinklers).

How is the link between EN 12845-2 and EN 12845-1 established?

TS EN 12845+A2:2026 Annex N (normative, EN p.162) for CMSA and Annex P (normative, EN p.164) for ESFR state that EN 12845-2 shall be applied together with this document and refer to Table A.1 or Figure A.1 in Annex A of EN 12845-2:2024 for the class conversion. Annex P also recommends the use of three 50% pump sets conforming to EN 17451 for the ESFR water supply.

In which type of installation may ESFR and CMSA be used?

Clause 4, EN p.6: ESFR sprinklers shall be used in wet installations only; CMSA sprinklers may be used in wet and dry installations. Clause 6.5, EN p.35: there is no dry installation option for the ESFR concept; where dry pendent ESFR sprinklers are used, the installation is considered to be a wet installation.

References

• TS EN 12845-2:2025 (EN 12845-2:2024), National Foreword and cover of the European Standard
• TS EN 12845-2:2025, Contents (EN p.2)
• TS EN 12845-2:2025, European foreword (EN p.3)
• TS EN 12845-2:2025, Introduction (EN p.4)
• TS EN 12845-2:2025, Clause 1 Scope and Clause 2 Normative references (EN p.5)
• TS EN 12845-2:2025, Clauses 3.1 and 3.2, Clause 4 (EN p.5-6)
• TS EN 12845-2:2025, Table 1 (EN p.7)
• TS EN 12845-2:2025, Clauses 5.1.1, 5.1.3.2, 5.1.3.3 (EN p.7-8)
• TS EN 12845-2:2025, Table 2 (EN p.10)
• TS EN 12845-2:2025, Clauses 5.2.1, 5.2.2 (EN p.12), 5.2.3 (EN p.13), 5.2.4 (EN p.16)
• TS EN 12845-2:2025, Clause 5.3.1 (EN p.21), Table 3 (EN p.23), Table 4 (EN p.24), Table 5 (EN p.26)
• TS EN 12845-2:2025, Clause 5.4 (EN p.32-33)
• TS EN 12845-2:2025, Clause 6.5 (EN p.35), Table 7 (EN p.36), Table 8 (EN p.37), Table 9 (EN p.38)
• TS EN 12845-2:2025, Tables 10 and 11 (EN p.41), Table 12 (EN p.43), Tables 13 and 14 (EN p.47)
• TS EN 12845-2:2025, Tables 15-21 (EN p.49-55), Tables 22-25 (EN p.57-58)
• TS EN 12845-2:2025, Annex A and Table A.1 (EN p.59), Figure A.1 (EN p.60)
• TS EN 12845+A2:2026, Annex N (EN p.162) and Annex P (EN p.164)

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