Fire Safety Systems Flashcards
Fire Safety Systems:
The functions of fire alarms and sprinkler systems are
To detect a fire at and early stage.
To sound a building occupant warning or alarm system.
To transmit a signal to summon the fire system.
To interface with other fire safety subsystems.
To commence extinguishment of the fire.
Fire Safety Systems:
The three types of dry alarms are
Heat detectors
Smoke detectors
Flame detectors
Fire Safety Systems:
Info about heat detectors
Used in applications where smoke detectors are not suitable such as in non-life safety installations where the environment has too many airborne particles due to excessive steam, moisture, dust, humidity or temperature, such as in attics, garages, warehouses, storage facilities, elevator machine rooms or electrical closets.
Heat detectors can operate via fixed temperature or rate of rise.
Fire Safety Systems:
Where would you find heat probes
Heat probe detectors are mostly found in kitchen exhaust hood or areas where the ambient temperature is excessively high. Their operating temperature varies and can be calibrated to range from 60-270 degrees.
Fire Safety Systems:
4 main groups of smoke detectors
Smoke detection as opposed to heat detection is specifically designed for the protection of life by its ability to detect fire in its early stages.
the 4 main groups are:
Point type
Beam type
Sampling type (e.g. VESDA Very Early Smoke Detection Apparatus)
Residential smoke alarms
Fire Safety Systems:
Point type smoke detectors
Detect smoke at a single point or location.
There is two main group of which they work:
Ionisation or Photo-electric
Fire Safety Systems:
Beam type smoke detectors
Made up of a transmitter and a receiver located on opposite walls of the building or room being protected. usually found in open areas such as atriums, convention centres and warehouses.
Beam detector relies on the breaking, by smoke, of a long light beam.
Fire Safety Systems:
Sampling type smoke detectors
The air sampling system draws air from the protected area through tiny holes in a pipe work system spaced out uniformly around the room. Pipes are connected to detector control unit where there is a fan that creates flow inside. The flow creates a slight vacuum which allows air to be drawn in. A dust filter reduces the chance on contamination. The air is then sampled at a central point by a sensitive light scattering detector.
Can be used in large areas and is very sensitive.
Fire Safety Systems:
Residential smoke detector/alarm
Used in residential housing, work on ionisation or photo-electric.
Are stand alone detector and alarm systems.
Powered by either battery or mains power.
New homes are required to have Smoke detectors connected to mains power.
Fire Safety Systems:
Main groups of flame detectors
Flame detectors are radiation detectors and belong to two groups:
Infra-red (IR)
Ultra-violet (UV)
Used in the following situations:
Flammable liquid storage
Fuel or lubrication systems
Aircraft hangers
Fire Safety Systems:
Sprinkler systems will be required in
Buildings over 25m.
Enclosed carparks accommodating more than 40 vehicles.
Occupancies of excess hazard, e.g. tyre storage facilities, factories.
Shopping centres over 3500m2.
Certain large isolated buildings.
Buildings with atriums installed.
Fire Safety Systems:
The basic functions of a sprinkler system are
Detect the presence of fire.
Locate the area involved in fire.
Raise the alarm, both with the occupants of the building and the fire brigade.
Attack the fire.
Fire Safety Systems:
Sprinkler system design classification
Sprinkler design and installation has been divided into three main hazard classifications: Light hazard (LH) Ordinary hazard (OH) High hazard (HH)
Fire Safety Systems:
Sprinkler system light hazard classification
Light hazard (LH) occupancies are non industrial premises where the amount and combustibility of the contents is low, e.g. Art galleries, churches, offices, etc.
Fire Safety Systems:
Sprinkler system ordinary hazard classification
Ordinary hazard (OH) occupancies are commercial and industrial occupancies involving the handling, processing and storage of mainly ordinary combustible materials unlikely to develop intensely burning fires in the initial stages. Further subdivided into 4 groups (OH1-4). Examples are footwear manufacturing, motor garages, and paper mills/storage.