Which Detector?

Which fire detector for which space?

There is no single best fire detector. Smoke, heat, beam, aspirating and flame detectors each suit different places, and the wrong choice means false alarms or a late warning. Pick a space below to see what is usually used there and why.

Choose a space

Open-plan office

Optical (smoke) point detectors

Why it fits
Smoke is usually the earliest sign of a fire in a normal workplace, and point detectors on the ceiling are the standard, well-understood way to catch it. Optical types respond well to the slow, smouldering fires that start in furniture and paperwork.
Watch out
Keep them clear of air vents and covers during building work, and have the system serviced on a regular schedule.

Kitchen or canteen

Point heat detectors

Why it fits
Cooking steam and fumes set off smoke detectors again and again. Heat detectors respond to temperature instead, so they ignore the cooking and still react to a real fire.
Watch out
Heat detectors react later than smoke detectors, so a designer may add other measures for the rooms next door.

Server or comms room

Aspirating smoke detection

Why it fits
Aspirating systems draw air through small pipes to a central unit that can pick up extremely low levels of smoke. That very early warning matters where equipment is valuable and downtime is costly.
Watch out
Pipe layout, airflow and sensitivity settings all need proper design and commissioning.

Warehouse or atrium

Beam detectors, or aspirating detection

Why it fits
In a very tall space, smoke can cool and thin out before it reaches a high ceiling. A projected beam covers a long line across the space, and aspirating pipes can be run where they will actually meet the smoke.
Watch out
Beams must stay aligned and unobstructed, and buildings move slightly over time.

Cable tray, tunnel or conveyor

Linear heat detector cable

Why it fits
A linear heat cable is one continuous sensing element laid along the hazard. It copes with dust, damp and awkward routes where point detectors struggle, and it reacts when any section gets too hot. Some types can also indicate roughly where along the cable the heat is.
Watch out
Choose the cable type and alarm temperature to suit the ambient conditions, and protect it from mechanical damage.

For a longer look at types and typical uses, see this guide to linear heat detector cable.

Fuel store or process plant

Flame detectors, with gas detection

Why it fits
Where flammable liquids or gases are present a fire can spread in seconds. Ultraviolet and infrared flame detectors respond to the flame itself and are chosen for exactly this kind of fast-moving hazard.
Watch out
Explosive atmospheres carry extra legal requirements in the UK (DSEAR) and equipment must be rated for the zone. This is specialist work.

Hotel, mall or large public building

Detection plus voice alarm (PAVA)

Why it fits
Detectors raise the alarm, but in a large building people also need clear instructions. A public address and voice alarm system can play recorded evacuation messages to the right zones instead of relying on bells alone.
Watch out
Speech must be intelligible in every zone, and the voice alarm has to be properly linked to the fire alarm panel.

New to the idea? This explainer covers what a PAVA system is and how it works.

Every system does three jobs

Detect

The right detector for the space, in the right place, at the right height.

Warn

Sounders, beacons or voice messages that everyone in the building can hear and understand.

Maintain

Regular testing and servicing. A system nobody checks is a system nobody can rely on.

Mistakes that cause trouble

Covering detectors during building work and forgetting to uncover them. Mixing detector types without a design. Putting smoke detectors in kitchens and then disabling them after the third false alarm. Skipping servicing because “it has never gone off”.

Who decides what is installed

In England and Wales, the responsible person for most non-domestic premises must carry out a fire risk assessment under the Regulatory Reform (Fire Safety) Order 2005. Fire detection and alarm systems in non-domestic buildings are normally designed to BS 5839-1 by a competent person. Scotland and Northern Ireland have their own legislation.