Two families of storage sprinklers dominate ceiling protection in high-rack warehouses: ESFR (early suppression fast response) and CMSA (control mode specific application). Within their table limits both can protect from the ceiling alone without in-rack sprinklers, but their limits, water demands and conditions of use differ. Every value below is taken from the 2025 edition of NFPA 13, with its section and table number.
The core difference: suppression versus control
- ESFR is designed to suppress a fire before it grows. The head opens very early and large, high-momentum droplets reach the top of the storage while the fire is still small. The design is based on 12 sprinklers (Section 23.2.2).
- CMSA is designed to control a fire: large droplets limit its growth. The design sprinkler count varies by table; most wet-system rack rows use 15 sprinklers (Table 22.4).
Technical comparison (NFPA 13-2025)
| Item | ESFR | CMSA |
|---|---|---|
| Relevant chapters | Installation Chapter 14, design Chapter 23 | Installation Chapter 13, design Chapter 22 |
| Response | Quick response | Quick or standard response (Sections 22.1.1 and 22.1.2) |
| K-factors in the tables | Pendent K14 (K200), K16.8 (K240), K22.4 (K320), K25.2 (K360); upright K14 and K16.8 (Table 23.3.1) | K11.2 (K160), K16.8 (K240) upright; K19.6 (K280), K25.2 (K360) pendent (Tables 22.2–22.5) |
| Design sprinkler count | 12 | Per table (13, 15, 20, 25, 30…) |
| System type | Wet; dry or preaction only with ESFR specifically listed for it (Section 14.2.2) | Wet, dry or preaction per the listing (Section 13.2.1.3); high temperature rating in dry systems (Section 13.2.2.4) |
| Highest ceiling, ceiling-only | 13.7 m ceiling / 12.2 m storage (Table 23.3.1) | 12.2 m ceiling (Tables 22.2–22.5); the only exception is roll paper, 18.3 m building height (Table 22.7) |
| Roof / ceiling slope | ≤ 4 in 12 (Section 14.2.3) | ≤ 4 in 12 (Section 13.2.1.2) |
| Deflector to top of storage | ≥ 36 in / 900 mm (Section 14.2.11) | ≥ 36 in / 900 mm (Section 13.2.8) |
| Solid shelves, open-top containers | Not permitted without in-rack sprinklers (Sections 23.1.3.1, 23.1.3.2) | Solid-shelf racks need in-rack sprinklers beneath all tiers under the highest solid shelf (Section 25.3.3.3) |
| Hose allowance and duration (Class I–IV, Group A) | Up to 12 sprinklers: 950 L/min, 60 min | Up to 12 sprinklers: 950 L/min, 60 min; 13–15 sprinklers: 1900 L/min, 90 min; 16–25 sprinklers: 1900 L/min, 120 min (Table 20.15.2.6) |
Above a 13.7 m ceiling: can you switch to CMSA when ESFR runs out?
Under NFPA 13-2025, no. CMSA ceiling-only tables stop at 12.2 m and ESFR tables at 13.7 m, so where ESFR no longer fits, CMSA does not fit either. Above 13.7 m the only ceiling-only option in NFPA is the alternative design in Chapter 24, Table 24.3.3: a dry system with high temperature, standard-response K33.6 (K480) upright sprinklers for Class I–III open racks, with 15.2 m and 16.7 m ceiling rows. Otherwise in-rack sprinklers are required.
EN 12845-2:2024 is different: ESFR reaches a 16.8 m ceiling with K400/K480 pendent sprinklers in Table 7, and dry CMSA is tabulated for HHS1/HHS2 with K480 upright sprinklers up to 15.2 and 16.8 m ceilings (Tables 18 and 21). FM Global DS 8-9 does not use the ESFR/CMSA names; it defines storage sprinklers by response and K-factor, and gives designs up to 16.8 m with quick-response pendent sprinklers (Table 17b) and up to 16.5 m with K33.6 in dry systems (Table 14a).
Hydraulic example: one warehouse, two solutions
Class IV commodity, rack storage, 10.7 m storage, 12.2 m ceiling, wet system. Flows use the nominal metric K-factor (Q = K·√P):
| ESFR K25.2 (K360) pendent | CMSA K25.2 (K360) pendent | |
|---|---|---|
| Table row | Table 23.3.1: 12 sprinklers @ 1.7 bar (25 psi) | Table 22.4: 15 sprinklers @ 1.6 bar (23 psi) |
| Flow per sprinkler | 360 × √1.7 ≈ 469 L/min | 360 × √1.6 ≈ 455 L/min |
| Sprinkler demand | 12 × 469 ≈ 5630 L/min | 15 × 455 ≈ 6830 L/min |
| Hose allowance (Table 20.15.2.6) | 950 L/min | 1900 L/min |
| Total | ≈ 6580 L/min | ≈ 8730 L/min |
| Duration and volume | 60 min → ≈ 395 m³ | 90 min → ≈ 786 m³ |
In this example ESFR needs less flow and roughly half the water volume; the 15-sprinkler CMSA design moves the hose allowance and duration up one step. These are minimum demands before pipe losses; the real demand comes from the hydraulic calculation.
Selection checklist
- Ceiling and storage height: in NFPA there is no CMSA table above a 12.2 m ceiling; ESFR is tabulated up to 13.7 m.
- Freezing risk (cold stores, unheated buildings): CMSA can be used in dry systems; ESFR only if specifically listed for dry or preaction systems.
- Solid shelves and open-top containers: ESFR cannot be used with them without in-rack sprinklers.
- Commodity: both families' tables give separate rows by commodity class; options narrow for exposed or expanded Group A plastics.
- Water supply: the choice follows the table row, not the pump or tank you happen to have; the water supply is then sized to meet that demand.
- Obstructions: each family has its own obstruction rules for beams, ducts and cable trays (Sections 13.2.7 and 14.2.10).
Frequently Asked Questions
What is the core difference between ESFR and CMSA?
ESFR is a quick-response sprinkler that opens very early to suppress a fire before it grows, and its design is based on 12 sprinklers. CMSA produces large droplets to control a fire; it can be quick or standard response, and the design sprinkler count depends on the table (mostly 15 for rack storage).
Can CMSA be used above a 13.7 m ceiling?
Not under NFPA 13-2025: CMSA ceiling-only tables end at a 12.2 m ceiling (the only exception is roll paper, Table 22.7). Above 13.7 m the only ceiling-only option in NFPA is the dry-system, standard-response K33.6 (K480) upright design in Chapter 24, Table 24.3.3; otherwise in-rack sprinklers are required. EN 12845-2 does tabulate dry CMSA for HHS1/HHS2 up to 16.8 m.
How do ESFR and CMSA water demands compare in the same warehouse?
For Class IV, 10.7 m storage and a 12.2 m ceiling, ESFR K360 (K25.2) needs 12 sprinklers @ 1.7 bar, about 5630 L/min, 6580 L/min with hose and about 395 m³ over 60 minutes. CMSA K360 (K25.2) needs 15 sprinklers @ 1.6 bar, about 6830 L/min, 8730 L/min with a 1900 L/min hose allowance and about 786 m³ over 90 minutes.
Which one is used in a cold store?
Where freezing rules out a wet system, CMSA can be used in a dry system with high temperature rated sprinklers (Sections 13.2.1.3 and 13.2.2.4). ESFR can be used only if it is specifically listed for dry or preaction systems (Section 14.2.2).
MEP Calc — 110+ Engineering Calculators
MEP Calc bundles 110+ engineering modules in one iOS app: 21 fire calculations (sprinkler, fire pump, FM-200 clean agent) plus heating, cooling, HVAC, plumbing, steam and natural gas. Download it on the App Store.
Download MEP Calc on the App Store
SprinkCalc — Fire Sprinkler Design Across Three Standards
SprinkCalc covers hazard classification, design density and area, K-factor selection, water demand and hydraulic calculations for NFPA 13, FM Global and BS EN 12845 in a single iOS app, and exports a professional PDF report. One of the few tools that unifies all three major fire protection standards.
Download SprinkCalc on the App StorePrimary sources: NFPA 13, 2025 edition — Chapters 13, 14, 20 (Table 20.15.2.6), 22 (Tables 22.2–22.7), 23 (Table 23.3.1), 24 (Table 24.3.3), 25; EN 12845-2:2024 Tables 7, 18, 21; FM Global DS 8-9 (March 2010, interim revision July 2025) Tables 14a and 17b. Values are for information; design must follow the full text of the edition in force and the product listing.