EN 12845 Block Plan, Signage and Marking Rules

However well a system is designed, if the question "where is the main valve?" goes unanswered during an alarm, loss is inevitable. Block plans, valve labelling and the fire service sign are the layers that take the least effort on site and save the most.

At a furniture factory, the night watchman spent eleven minutes looking for the pump room after hearing a sprinkler alarm. The signage was not in the local language — "WET RISER", "DRY RISER", "MAIN VALVE" plates left over from an imported design five years earlier. The fire went out because the sprinklers worked; but had they not, eleven minutes would have made an unknowable difference in square metres. EN 12845 Clause 18 is explicit that marking is not a convenience but an integral part of the system.

Clause 18 — marking requirements

The block plan sign

A permanent, durable, visible sign is fixed near every control valve set. Minimum content:

• System type (wet, dry, pre-action, alternate)
• Hazard class (LH, OH1–4, HHP1–4, HHS1–4) and storage type (ST1–ST6)
• Design density (mm/min) and area of operation (m²)
• Water supply type (town main, tank, pump) and capacity (m³, minutes)
• Boundaries of the protected area (floor, block, room)
• Zone numbers and boundaries, where applicable
• Designer, installing contractor and commissioning date
• An emergency contact number
• The standard reference, for example "EN 12845:2015+A1:2019"

The sign should be A3 minimum, in aluminium or weather-resistant laminate, with lettering at least 5 mm high. In a foreign-owned facility it may be bilingual.

Valve labelling

Every stop, alarm, drain and test valve must be labelled. The minimum:

• Valve function, for example "Z3 STOP VALVE — DO NOT CLOSE"
• Normal position (open or closed)
• The zone or area served
• The locking point, where locking is required

Labels in plastic or aluminium, wired or adhered. Red background with white lettering is the usual convention.

Pipe direction and colour

EN 12845 does not itself require painting; national codes call for the red sprinkler pipe convention. A flow direction arrow and the word "SPRINKLER" every 6 m along the main is the normal practice.

Example block plan content

Field	Example value
System type	Wet pipe sprinkler
Hazard class	HHS3, ST4 rack storage
Design density / area	12.5 mm/min / 260 m²
Sprinkler type	K115 pendent, 79 °C
Water supply	2 × electric pump plus 540 m³ tank
Duration	90 min
Number of zones	4 (Z1–Z4)
Total sprinklers	1240
Standard	EN 12845:2015+A1:2019

The fire service sign (outside the building)

Positioned near the main entrance, within the line of sight of an arriving appliance. Content:

• Building name and address
• Location of the main sprinkler stop valve (floor and room)
• Location of the pump room
• Location of the fire service inlet connection
• Water tank location and capacity
• Location of the fire detection panel
• Hazardous material warning, where relevant

The sign should be fire resistant for at least 60 min, reflective, and typically 600 × 400 mm.

The spare sprinkler cabinet

A cabinet of spare sprinklers of the same type and temperature rating as the installed system:

Total sprinklers	Spares required
Under 300	6 of each type
300–1000	12
Over 1000	24

The cabinet sits beside the control valve set, locked, and contains the sprinkler wrench. A transparent or labelled door lets the contents be seen from outside.

Field error — the wrong valve was closed

At a shopping centre, an electrician wanted to isolate a circuit during routine maintenance and was told to "just close the main valve briefly". He closed one of a set of unlabelled valves — which turned out to be the Z2 sprinkler stop valve. Six hours later an insurance audit found it and recorded "valve found closed". The facility had been effectively uninsured for six hours, and any fire in that window would have voided the claim. Had the labelling clause been applied, the electrician would never have touched it.

Synchronising the zone map with the alarm panel

Sprinkler zone numbers must be identical in three places:

1. On the block plan sign
2. On the zone valve
3. On the fire detection or sprinkler alarm panel

If the alarm says "Z3 flow", the valve says "Zone-3" and the sign says "Area C", the operator spends thirty seconds navigating a map. A single coding scheme — "Z3" everywhere — is essential.

Lighting and visibility

Every sign must remain readable when normal lighting fails:

• Under emergency lighting to EN 1838
• Reflective or photoluminescent printing
• No obstruction in front — at least 1 m clear all round
• Annual cleaning and legibility check, on the periodic inspection list

Comparison with NFPA 13 and NFPA 25

NFPA 13 and NFPA 25 impose comparable block plan and valve marking requirements. NFPA adds a "hydraulically calculated" placard, recording density, area and flow on a hydraulically designed system — which EN 12845 already requires. Spare sprinkler quantities are the same 6/12/24 scale in NFPA 13. The two standards align closely enough that a single sign can satisfy both.

Link to Turkish regulation

BYKHY requires a marking plan, a valve location drawing and a fire service information sign within the fire safety file, and Clause 18 satisfies that. In practice, signage in Turkey is frequently missing or wrong for years at a time. Missing signage is a common reason for a fire service inspection to return "conditionally compliant", delaying the occupancy permit. The cost of signage is well under 0.1 % of a system; its absence makes the whole system meaningless.

Quick check list

• A block plan sign at every control valve set, A3 minimum, weather resistant.
• All valves labelled with function, normal position and area served.
• Fire service sign outside, within line of sight.
• Spare sprinkler cabinet with the correct quantity and the wrench.
• Zone numbering identical on sign, valve and alarm panel.
• Signs readable under emergency lighting.
• 1 m clear around each sign.
• Legibility confirmed at the annual inspection.

Frequently Asked Questions

What goes on a block plan sign?

System type, hazard class and storage type, design density and area, water supply and capacity, protected area boundaries, zone numbers, the parties involved, an emergency number and the standard reference.

How many spare sprinklers must be kept?

Six of each type below 300 installed sprinklers, twelve between 300 and 1000, and twenty-four above 1000 — in a locked cabinet with the sprinkler wrench.

Why must zone numbers match in three places?

Because the alarm, the valve and the sign are read by three different people under pressure. If they use different naming, the response stalls while someone reconciles them.

What does a fire service sign need to show?

Building identity, the main stop valve location, the pump room, the fire service inlet, the tank location and capacity, the detection panel, and any hazardous material warning.

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