Fire Detection And Alarm System In Electrical Construction Works



The scope of this specification covers the supply, installation, testing and commissioning of an Automatic Fire Detection and Alarm System including wiring. All materials and equipment used in the work shall be ISI approved and installed with a high degree of workmanship.

Fire Detection And Alarm System In Electrical Construction Works

The installation as a whole shall comply in all respects with ISI code of practice for Automatic Fire Alarm System (IS 2189-1976) however, contractor shall comply with the latest or superseded versions of IS/BIS to be used for the complete work. It shall be contractor's responsibility to have installation approved by the Fire Brigade and all other concerned authorities.

1. Fire Alarm System (General)

You can read more about what is Fire Detection and Alarm System here.

Each floor shall be divided into zones. Each zone shall be wired up with the required number of fire detectors for fast fire response and efficient functioning and shall be connected through control cables to the floor signal panel which in turn shall be connected to the main fire console to be installed on the ground floor. The main consoles and floor signal panels shall have sufficient number of zones to cater to all floors of the building plus a few additional zones to cater to future extension if required. Manual call stations shall also be provided at all floor landings and connected to the nearest zone of fire detectors.

2. Main Console & Floor Signal Panels

  1. These panels shall be designed and manufactured for the required number of zones in each floor. They shall be of cubicle pattern suitable for wall mounting. The system shall be electronic solid state construction using the highest quality components. The panels shall be modular construction with segregation of circuits by means of plug-in printed cards having gold plated terminal contacts for high efficiency operation. Any zone may be isolated within the system. If required, without rendering the balance of the system inoperative. Similarly, the alarm section shall continue to sound if calls are received from different zones even if the entire system has not been reset after receipt of the fire alarm call. Supply with each zone being illuminated by red or yellow lamp indicators to sign 'fire' or fault conditions. Each indicator unit shall have two lamps connected in parallel to comply with F.O.C recommendations. The system shall be fully monitored at all times and shall be contained within a sheet metal dust-tight enclosure. After installation, the control panels shall be completely tested for all their circuit facilities. The panel shall be given stove enameled painting after degreasing and phosphatising.
  2. The following extra features shall be incorporated in the system.
    1. A separate amplifier suitably rated to cater to the entire building with provision for 'Alert' 'Excavation' and 'Public Address' systems.
    2. Microphone for the above amplifier.
    3. Facility for connecting electric siren and auto-manual switch.
    4. Standby Dry Batteries source in case of main failure.
    5. Facility from Manual Call Point for duplex communication.
  3. The detailed technical specifications of the micro-processor based fire alarm panel with in built public address talk back telephone facilities shall be generally in accordance with the following description:
    1. Micro Processor based Fire Alarm Panel is the state of art design product offering multitude of advantages and several special features. Though the electronic circuits are entirely different, the users interface is almost similar standard Electronic Fire Alarm Panel. The low component count and high density design technique results in compact size and higher MTBF.
    2. The system is made up of several blocks as shown in the drawing, whose functions are as under:

3. RPS Regulated Power Supply:

RPS receives input from 230 V, 50 Hz, AC mains source and delivers regulated 24 V DC to various blocks of the system as well as to the batteries for charging. RPS also contains 24 V/ 5V optically isolated Converter for powering CPU (Central Processing Unit).

4. CPU (Central Processing Unit):

CPU incorporates important circuit components like Bit Micro Processor crystal clock program memory, search pad and key board display interface.

CPU receives information from SM-1 & SM-2 (Status Monitor) regarding the status of Fire Detectors connected on them. CPU stores the information temporarily and analyses according to the memory protocol. It also receives various commands from the key-board. It then gives out information to LM) (LED Module), OAD (Order of Alarm Display and RD (Relay Driver).

5. SM-1 & SM-2:

Each Module Monitors 16 detector line status. The CPU continuously upgrades and addresses and accordingly SM scans detector lines, 2 No. at a time for higher speed. The detector line voltage which is a measure of detector status is applied to converter circuit, which generates digital word and is fed to ADU through optical isolation. This eliminates the possibility of any damaging voltage reaching the CPU.

6. Key Board:

It is a 12 Key Key-Board. 10 Keys are used for standard function and balance for optical functions. The Key Board allows user to manipulate the system for testing and alarm control functions.

7. LM (LED Module):

LED matrix indicates the status of 32 detector lines. The detector line could be one of the 5 status namely "NORMAL", "FIRE", "SHORT", "OPEN" or "ISOLATE".

8. OAD (Order of Alarm Display):

Order of Alarm Display Module has 7 segments,2 digits display 3 Nos. in all, which indicate the order of occurrence of Fire Alarm zone-wise, sequentially on first-cum-first basis subject to a maximum of 3 different zones under fire.

9. RD (Relay Driver):

Relay Driver Module can drive external relays corresponding to respective line. It also has common alarm, common fault and scan indicators. The flashing LED indicates that SCAN process is 'ON'. External Relay for every zone is used for repeat fire alarm panel, paging and engineering automation function like signal to Central Computer.

10. Public Address:

Facia of Panel has 32 Toggle Switches (1 per zone), which in conjunction with auxiliary relays above operate Public Address System either in auto manual mode. It also has 2 Nos. Master Toggle Switches which allow the input selection namely alert, evacuate or speech.

11. Telephone System:

The facia plate also has 32 Nos. sockets, which are wired in series with detector lines. This allows the use of pair of detector wires as telephone line for 2 way communication. When the Operator inserts telephone jack of portable set in a socket mounted on a call point, the Panel Operator gets an indication, which enables him to plug-in telephone hand-set in the jack, thereby establishing communication. This facility is established only from call point to Panel and not vice versa.

12 OPERATION:

For easy understanding of the operation, facia details of Panel shall be generally as illustrated hereunder:

Operation of the Panel is divided into two modes:

1. Normal

2. Simulation

In Normal mode, Control Panel is monitoring all detector lines connected to it. Flashing LED inside the cubicle indicates that the 'scanning' is 'ON'. If a cable fault occurs on any of the detector line (external to the panel), it is indicated by Amber LED either 'Open', or 'Short' as the case may be. The Sounder will also produce the audio tone simultaneously. Immediate action required to be taken is to silence audio fault tone by pressing 'Accept' Switch from the Key-Pad. User then will have to investigate and rectify cable fault in the system.

If a detector line produces alarm signal either due to operation of detector or operation of Manual Call Point, twin Red LEDs of that zone will illuminate. First row of 7 segment display will indicate zone number and simultaneously audio tone will be raised, which will be different from tone under fault condition. The operator will silence audio tone pressing 'ACCEPT'. He will locate the spot of fire and take required action. On taking the required remedial action, affected zones can be restored back to normal condition by pressing the 'RESET' switch. Simulation:

Healthiness of the panel can be periodically checked by simulating above fault and fire condition.

For simulating Open or Short condition, press the respective switch, which will operate LEDs of the zones sequentially within 5 seconds maximum.

For simulating Fire Test, press switch 'FIRE', select particular zone by pressing switch '10' or switch '12'. Press switch 'ENTER'. This will generate same conditions as 'FIRE' described above. Take further action same as above under 'FIRE' for re-setting the zone.

There is also provision of isolation of zones, which can be achieved as under:

Press 'ISOLATE' switch, which will be indicated by Isolate LED of Zone 1. Select particular zone to be isolated by a switch '10' or '12' and press 'ENTER'. For re-setting isolated zone press switch "ISOLATE", wait till zone number is reached and press 'ENTER' again.

The Panel has PA system with alert, evacuate tone and any of these facilities can be achieved by operating respective switch provided. Two way communication can also be achieved by inserting portable hand set in the socket of Call Point. This will be indicated on the panel by open LED of the respective zone. The person at the panel has to insert telephone jack in the respective socket and establish communication.

13. Automatic Fire Detectors

The detectors offered shall ensure complete reliability of the systems besides being modern in appearance and functional in design. All types of detectors shall be suitable for use on low voltage DC power supply. The detectors shall have the approval of the Insurance Fire Offices Committee and the Insurance Association of India - Bombay Regional Council.

14. Heat Detector

The detector should operate on a rate-of-rise principle combined with a fixed temperature thermostat. Each detector shall incorporate its own diaphragm and compensating vent which should be sealed against dust, humidity and corrosive air particles, etc. The settings should be 10 Degree C/minute temperature increase for rate of rise elements and + 70 Degree C for fixed temperature elements.

14. Smoke Detectors

This detector shall operate on a twin chamber ionization principle with sensitivity adjustment to meet F.O.C requirements . It shall detect both the visible and invisible products of combustion-smoke and gas produced during the incipient stages of fire. Size and colour of the aerosols shall not have a decisive influence on the response of the detector. The detector shall be assembled with least possible number of components which are not subject to wear. Each detector shall blink until the alarm is canceled at the main signal panel. The working of the detector shall not be affected by the failure of the indicator lamp and it shall be possible to replace the indicator lamp if it fails. Interchanging of detectors shall be effortless and all parts exposed to external influence shall be to dismantle without loosening screws and connectors. The detectors shall be vibration and stock proof. The detector components sell not get changed due to static over voltage and be designed to be practically immune to environmental criteria such as air currents, humidity, temperature fluctuations, etc. The level of radio-activity in the detector shall be very low so as not to harm persons or objects. The detectors shall be suitable for surface or flush mounting as required.

16. Break Glass Call Point

The units shall be suitable for surface or flush mounting as required and manufactured out of die-cast aluminium. A push button switch mounted on a metal plate shall be held in the 'closed' position by a glass plate fixed within the front frame. When the glass is broken, push button shall be released automatically, thereby breaking the circuit which shall cause the alarm system to operate. A small hammer shall be supplied with each unit for the glass in the event of a fire.

17. Halon 1301 Fire Suppression System

Prime areas shall be provided with Halon 1301 Fire Suppression System. The Halon 1301 Modules shall be mounted at the ceiling levels in the room. The modules shall have electric actuators connected to the Main Control Panel. On activation of the Smoke Detectors and/or photo electric detectors in the rooms, a timer in the control panel shall come into operation. After pre-set time, the Halon module will be punctured by the actuator, releasing the Halon gas. The Halon Module actuator shall also be controlled manually from the Main Control Panel.

18. Electrical Alarm

These electronic alarm devices shall be located on all floors as indicated on the drawings and shall generate strong signals via a loud speaker. The alarm shall have a choice of two levels of sound intensity and should be designed such that the alarm tone can be interrupted to give spoken messages such as instructions from Fire Brigade Personnel, etc.

19. Fire Detection and Alarm System Wiring

The complete wiring interconnecting the various equipment of the fire alarm system shall be carried out with suitably rated PVC insulated and armored copper conductor cables and copper conductor wires in MS conduits. The wires shall be of 1.5 sq. mm copper conductor.

20. Testing

The Fire Alarm Panel shall be subjected to all necessary tests during commissioning and after completion of work.

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