NFPA 72

Fire Detection & Alarm System

DTL does not manufacture detection. Where a scheme calls for it, panels and field devices from represented brands are supplied, installed and integrated under the same contract as the suppression system.

Discuss your scheme

At a glance

Governing standard: NFPA 72
Designed to: NFPA 72, IS 2189, NBC 2016 Part 4

How it works

Schematic of a fire detection & alarm system, showing how water, agent or signal flows through it

A detection and alarm system finds a fire early, raises the alarm, and sets off everything else that has to happen: releasing a suppression system, shutting down ventilation, closing fire doors and telling people to leave.

What it is made of

Detectors matched to the risk: smoke detectors for ordinary areas, heat detectors where smoke would give false alarms, flame detectors for open process areas, linear heat cable along cable trays and tank seals, and aspirating detection where the earliest possible warning matters.
Manual call points on escape routes.
Sounders and beacons to raise the alarm.
A control panel that monitors every device and its wiring, shows where the alarm came from, and drives the outputs.

Addressable and conventional

An addressable system identifies each device individually, so the panel names the exact detector in alarm and a fault can be traced to one device. A conventional system reports by zone. Addressable is the norm on industrial sites, where knowing precisely where a fire is changes the response.

Integration

The value is in the interfaces. The cause-and-effect matrix programmed into the panel decides what each alarm does — which suppression system it releases, which fans stop, which doors close — so detection and suppression work as one system rather than two.

Detector types

Detector	Senses	Suits
Optical smoke	Smoke scattering light	Offices, control rooms, most indoor areas
Heat, fixed or rate-of-rise	Temperature, or how fast it rises	Kitchens, workshops, dusty areas
Multi-sensor	Smoke and heat together	Areas prone to false alarms
Aspirating	Air sampled through pipes	Data halls, clean rooms, early warning
Beam	Smoke across a long open space	Warehouses, atria, hangars
Linear heat	Heat along a cable	Cable trays, conveyors, tank rim seals
Flame	Radiation from a flame	Open process areas

Standards

NFPA 72National fire alarm and signalling code.
IS 2189Selection, installation and maintenance of automatic fire detection and alarm systems.
NBC 2016 Part 4Fire and life safety in buildings.

Design basis

Parameter	Figure	Source
Smoke detector spacing, smooth ceilings	9.1 m nominal	NFPA 72
Manual call points	Within 1.5 m of each exit; travel distance to one not more than 61 m	NFPA 72

Service and maintenance

A fire protection system only performs if it is kept in the condition it was commissioned in. Inspection, testing and maintenance to the intervals the code sets — under an annual maintenance contract or as a single visit.

What it involves

Task	Interval	Reference
Visual inspection of panels, devices and batteries	Six-monthly	NFPA 72
Functional test of every detector and call point	Annually	NFPA 72
Smoke detector sensitivity test	Every 2 years after the first	NFPA 72
Test interfaces to suppression, ventilation and lifts	Annually	NFPA 72

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Why De’s Technico

Represented brands
Panels and field devices from the detection brands we represent, supplied, installed and integrated under the same contract as the suppression system.
4 installations on record
Our project record lists 4 fire detection and alarm installations, from design through commissioning.
One contract, design to handover
A lump-sum turnkey scope on single-window responsibility: design, engineering, supply, installation and commissioning answer to one schedule.
In fire protection since 1988
More than 35 years of designing and executing fire detection and protection systems for high-hazard industry.

Questions we are asked

Addressable or conventional?

Addressable identifies each device, so the panel names the exact detector in alarm; conventional reports by zone. Addressable is the norm on industrial sites.

Which detector for which area?

Smoke detectors for most indoor areas, heat detectors where smoke or dust would cause false alarms, and flame or linear heat detection for open process areas, cable trays and tank seals.

Can the alarm system release suppression?

Yes. The cause-and-effect programmed into the panel can release deluge, foam or gas systems, stop ventilation and close doors.

How often is it tested?

Under NFPA 72, every detector and call point is tested each year, with visual inspections in between and smoke detector sensitivity checked every two years.

Do you manufacture the detectors?

No. Panels and devices come from the brands we represent; we supply, install, program and commission them under the same contract as the suppression system.