Fire detection and extinguishing systems

Fire detection systems

Early detection allows escape and quick action. Types of detectors:

1. Heat detectors: fixed-temperature (fusible link, bimetallic) or rate-of-rise types; respond to temperature increase; used in kitchens, boiler rooms.
2. Smoke detectors: ionisation type (good for flaming fires) and optical/photoelectric type (good for smouldering fires); used in rooms, corridors, offices.
3. Flame detectors: infrared or ultraviolet sensors for hazardous areas.
4. Gas detectors: detect combustible gases and CO.
5. Manual call points: break-glass push buttons.
6. All connect to a fire alarm panel with bells/sirens and indicator zones.

Fire extinguishing systems

1. Portable extinguishers: water (Class A), foam (A, B), CO2 (B, C, electrical), dry chemical powder (A, B, C), wet chemical (kitchen oils).
2. Hose reels and hydrants: pipes with hoses on each floor and outside hydrants.
3. Wet riser / dry riser: vertical pipe to supply water to floors in tall buildings (wet riser always charged, dry riser charged by fire brigade).
4. Automatic sprinkler system: pipe network with heat-sensitive bulbs (about 68 degrees C glass bulb) that burst and spray water over the fire.
5. Gaseous / foam systems: CO2, inert gas, or foam flooding for server rooms, stores and oil hazards.
6. Water storage: underground static tank and terrace tank with pumps (main, jockey, standby).

 Terrace tank
    |
  riser ---[hose reel] floor 3
    |-----[hose reel] floor 2
    |-----[hose reel] floor 1
  pump <- underground tank