Fire alarm system-design secrets

Addressable  system design secrets:

·      Distance between Smoke Detector mustn’t exceed 10 m to avoid dead area between detectors

·      Distance between heat Detector mustn’t exceed 7 m to avoid dead area between detectors

·      Fire detector must be mounted at least one meter from any forced air inlet.

·      Ramps at car parking must be covered by heat detectors

·      Voice evacuation located at escape stair must be in a separate loop.

·      Fire fighter telephone must be located at elevator lobbies & pump rooms.

·      Each fire loop must have 20% spare capacity.

·      Access control system ( ACS ), elevator, Door holder,Public address system ( PA ), exhaust fan’s, Air Handling Units( AHU’S ) connected to fire alarm system via control module ( CM )

·      Fire fighting system( FM200, CO2, Sprinkler system( flow switch & Tamper switch ) ) connected to fire alarm system via monitor module ( MM ).

·      Alarm bell located at 2200mm above finished floor level.

Fire alarm system

Codes & standard

·         NFPA ( National Fire Protection Association ) 

·         BS 5839 ( British Standard )

·         VDS ( Germany)

 

System types:

·         Addressable  system

·         Conventional system

·         Wireless  system

Addressable  System Components:

-          Smoke Detector

·         2 types (optical smoke detector & ionization smoke detector ( not used now) )

·         Located at

§  all rooms, halls, storage areas, basements, attics, elevator, shafts, enclosed stairways, dumbwaiter shafts, and chutes.

§  Cover area with raduis ( r= 5m )  toatal area equal πr square = 80 meter square.

-          Heat detector

·         2 types ( fixed heat detector & rate of rise heat detector)

·         Located at:

§  generator room, Kitchen & Boiler room.

§  Cover area with radius ( r= 4m )  total area equal πr square = 50 meter square.

-          Multi-sensor ( smoke & heat ) detector

·         Locate at: ( electrical, communication, mechanical & control )rooms

-          Flame detector

·         2 types ( Ulta-Violet UV & Infra Red)

·         Locate at:

§  petrol station & workshop nearest to source of flame

-          Beam detector

·         Consists of transmitter  ( T ) and receiver ( R ), Located at wide open plan areas

-          Gas detector

·         Located at Kitchen nearest to source of gas

-          Carbon Monoxide detector

·         Located at place that may be contain co gas as garage area

-          Duct smoke detector

·         Located at HVAC duct at return & supply

-          Manual station

·         Locate at:

§  Entry/Exit doors, at corridors every 61 m at height not less than 1.1 m and not more than 1.37 above floor level as per NFPA requirements

-          Fault Isolator

·         Located very 20 device inside fire loop to make loop continue working in case of any short circuit in the loop

-          Control module

·         Used to control exhaust fan’s,Air Handling Units ( AHU’S),Elevators...............

-          Monitor Module

·         Used to monitor fIre fighting system as ( FM200, CO2..........)

-          Fire  alarm repeater panel ( FARP)

·         Used to show faults as in main fire alarm panel but no action can be taken from FARP, Located at any floor beside counter areas

-          Types of alarms

·         May be  audio / audio with strobe / strobe

-          Alarm devices

·         Bells

·         Horn speaker ( outdoor )

·         Evacuation with Strobe light ( Flasher )

-          Types of cable used in fire alarm systems

·         Fire retardant cable till 105  ͦC 

·         Fire resistance cable [ 750 ͦ ,950 ͦ,1050 ͦC]

·         Fire  alarm cable must be Copper conductor ( retardant or resistance )with cross section

·         2 ( 1pair ) x 1.5 mm( cable cross section )

·         Cable cross section depend on number of device ,detector & loop length  

-          Types of conduits  used in fire alarm systems

·         PVC Conduits used in embedded installation 

·         EMT Conduits used in Exposed installation

·         UPVC Conduits used in outdoor installation

Fire Alarm Control Panel ( FACP ), Workstation & batteries