Fire detection and alarm systems are designed to provide warning of the outbreak of fire and allow appropriate fire fighting action to be taken before the situation gets out of control. Primary function of fire detection system is to detect fire and provide audible and visual warming for occupants to evacuate the building. System is also linked by CMS (central monitoring system) to nearest local fire station so they can response immediately.
As all systems are designed primarily to protect life and property, this places a great responsibility on the designer because each building will present a different set of problems in relation to the risk of fire and fire spread. Each fire detection and alarm system therefore must be specially designed to meet the requirements for each category of building to suite the environment and the occupants.
The fire alarm system can either be operated automatically or manually. Automatic operation is via the detectors whereas manual operation is by breaking the glass at the manual call point unit or press the reset-able plastic of the manual call point unit to raise an alarm.
The manual/automatic actuation of the detectors will cause an alarm condition on the master fire alarm panel which will then actuate all the audible alarm units e.g. bells, sirens and visual alarm units e.g. flashing lights installed. For highrise or large buildings, two stage alarm is normally designed to identify the floor/zone on fire with continuous sounding of audible alarms and intermittent sounding of audible alarms on the rest of the floors or zones.
A set of standby battery with capacity for 72 hours supply is provided to support the main fire alarm panel in the event of any power failure over long weekend holidays.
Design Codes and Standards
a. BS 5839: Part 1, 3 and 5
b. MS 1176: Part 5, 7 -9
c. MS1471: Part 3
d. MS 1745: Part 1-5, 7, 11-15
c. BS EN 54: 9-10, 16-18, 20-27
d. BS 7273
e. BS 6266
Components of Fire detection and alarm system
a. Smoke – Photoelectric smoke detector
d. Multi-sensor – heat, smoke and carbon monoxide
e. High sensitivity smoke detector
g. Beam detector
h. UV/IR Flame detector
B. Manual Call Point
C. Audio and Visual Alarm Unit
D. Main Fire Alarm Panel
E. Wiring in conduit
F. Back-up batteries
Type of Fire Alarm and Detection System
There are few types of fire detection systems:
- Conventional Analogue system
- Digital /Analogue addressable system
- Semi-addressable system
- Digital addressable system
- HSSD system – High Sensitivity Smoke Detection System
- Linear Detection System
- Wireless system