CMDA vs CMSA vs ESFR — Three-Mode Comparison

Three sprinkler philosophies: control (CMDA), large-droplet control (CMSA) and early suppression (ESFR). Which one goes where, why the water demands differ so much, which the insurer prefers and which is practical in a warehouse — with a decision matrix and field cases.

An e-commerce warehouse with 9 m Class III storage received three tenders: CMDA at 3250 L/min for 90 min (inadequate), CMSA plus in-rack at 4500 L/min with hangers at every level (complex), and ESFR K360 at 5500 L/min for 60 min (simple). ESFR was chosen — the roof slope was 3 % and the skylights 4 m². Eighteen months later the racking was raised to 12 m and the ESFR listing was breached. A decision matrix has to account for every growth scenario from the outset.

The three modes in brief

• CMDA (Control Mode Density Area): the classical EN 12845-1 approach — a density in mm/min over an area in m². K80–K115. Control the fire; the fire service extinguishes it.
• CMSA (Control Mode Specific Application): large droplets, commodity-specific. K115–K240. Fewer sprinklers, but large droplets that knock the fire down.
• ESFR (Early Suppression Fast Response): low RTI plus high pressure plus large droplets. K200–K480. Suppresses the fire outright.

Comparison table

Aspect	CMDA	CMSA	ESFR
Objective	Control	Large-droplet control	Suppression
Standard	EN 12845-1	EN 12845-2	EN 12845-2
K-factor	K80–K115	K115–K240	K200–K480
Pressure	0.5–2 bar	2–4 bar	3.5–5.2 bar
RTI	About 200 (standard response)	50–80	≤ 50
Design basis	Area × density	15–30 sprinklers	12 sprinklers
Duration	30–90 min	60–90 min	60 min
Roof slope	Flexible	≤ 17 %	≤ 5 %
In-rack	Usually required	Frequently combined	Usually not required

Storage height and mode selection

Storage height	Recommended mode	Note
≤ 4 m	CMDA	OH3 density is sufficient
4–6 m	CMDA plus in-rack, or CMSA	HHS3–4
6–9 m	CMSA at ceiling, or ESFR	HHS5–6
9–12 m	ESFR if the roof allows, otherwise CMSA plus in-rack	—
≥ 12 m	ESFR with insurer-specific listing, or CMSA plus in-rack at every level	Requires a dedicated study

Water demand compared (9 m Class III storage)

Mode	Design basis	Total flow	Duration	Tank
CMDA	12.5 mm/min over 260 m²	3250 L/min (inadequate)	90 min	Not recommended
CMSA K200 plus in-rack	15 heads at 3 bar plus 6 in-rack	4500 L/min	90 min	405 m³
ESFR K360	12 heads at 4 bar	5500 L/min	60 min	330 m³

Decision matrix — seven criteria

1. Storage height, both current and projected five years out
2. Commodity classification (class or group)
3. Roof slope, skylights and ventilation
4. Water supply capacity (town main plus tank)
5. Space available for the pump room and tank
6. Maintenance access (in-rack heads are harder to service)
7. Insurer preference (FM Global favours ESFR; VdS and LPCB are more flexible)

Field error — growth ignored

A logistics warehouse chose ESFR K200 at 7 m storage with a suitable roof. Two years later the racking was raised to 10 m, exceeding the 7.6 m limit of the K200 listing. The remedy was expensive: the whole ceiling was converted to K360 and the pump upgraded. The question "what happens in five years?" belongs in the decision matrix from day one — changing mode later typically costs several times the original installation.

Insurer preferences

• FM Global: favours ESFR, with a restricted list of approved products
• VdS (Germany): flexible, accepts CMSA plus in-rack
• LPCB (UK): full support for EN 12845-2
• International insurers in Turkey: EN 12845 as the reference, with FM Global taking precedence
• Domestic insurers: BYKHY plus EN 12845 generally sufficient

Indicative cost comparison

For a 1000 m² warehouse at 9 m Class III storage, order-of-magnitude figures only — local market conditions dominate:

• CMDA plus in-rack: highest head count and the most hanger work
• CMSA at ceiling plus in-rack: mid-range on capital cost
• ESFR at ceiling: lowest installation scope but the most expensive pump set
• Over a 20-year life cycle ESFR usually wins, because there is no in-rack maintenance

Turkish regulation and local practice

BYKHY does not distinguish between the three modes; it accepts EN 12845 or NFPA 13 as equivalent. Large logistics operators favour ESFR, while facilities built in the 1990s and 2000s continue with CMDA plus in-rack. Newer distribution centres treat ESFR as the default, and insurance premiums are typically meaningfully lower for ESFR-protected buildings.

Quick check list

• Storage height documented for today and five years out.
• Commodity classification checked against the classification annex.
• Roof slope and skylight areas measured.
• Mode agreed jointly with the insurer, in writing.
• Parametric tenders obtained for all three modes.
• Twenty-year life-cycle cost calculated.
• The cost risk of changing mode later is documented.

Frequently Asked Questions

What is the core difference between the three modes?

CMDA controls a fire until the fire service arrives. CMSA uses large droplets to knock it down. ESFR is designed to suppress the fire outright with fast-response heads at high pressure.

Which mode suits 9 m storage?

Either CMSA at ceiling with in-rack, or ESFR if the roof is within the 5 % slope limit and skylights are small. ESFR is simpler to maintain; CMSA is more tolerant of an imperfect roof.

Why does ESFR use a shorter duration?

Because it is designed to suppress rather than control. EN 12845-2 allows 60 min for ESFR against 90 min for CMSA, which partly offsets the higher instantaneous flow.

What is the most expensive mistake in mode selection?

Ignoring future storage growth. Raising racking beyond the listed height voids the design, and converting the ceiling and pump afterwards typically costs several times the original installation.

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