Common Terminologies in Fire Alarm System
1.Fire Detection System
It is notable that, only fire suppression systems will not be sufficient enough to protect the human life. So you may need to warn the residents well in advance, when some incident is detected at the very early stages, so that the residents can safely evacuate from the location.
2. Detectors
Smoke and Heat detectors are provided to detect the presence of smoke particles in air and elevated temperatures (more than ambient temp.) respectively, where they are installed.
Smoke detectors has more faster response time than the Heat detectors.
Smoke detectors can be ionization or Optical type detectors.
Flame Detectors are fire sensing detectors that detects radiant energy from the flame. It can be UV Or IR or a combination of IR/UV. It can also be Multi Spectrum IR Flame detector.
Beam Detectors are those which detects the smoke with the help of a projected beam of light. It has a source and a receiver, and the coverage area of this type of detector is 1500 m2.
Air Sampling Detectors are those in which air is sucked through the pipes from the location and smoke particles are analyzed. It permits the sensor to placed out of harm. It is also known as VESDA System (Very Early Smoke Detection Alarm System).
Gas Detectors detects the level of gas concentration using infrared absorption method by measuring the variation of sound velocities in different gas concentration.
3. Fire alarm Installation standards
Fire alarm systems, Emergency signaling and communication systems are installed as per NFPA -72 standard guide lines. BS-5839-Fire Detection and Alarm System for Building – code of practice of installation and servicing,UK.
4 .Factors Affecting Performance of Fire Detectors
Sensitivity, Reliability, Maintainability, Stability.
5. Manual Call Points (MCP)
They are such manual overrides and can be operated by people all around and it works in conjunction with various detectors, if they detect any incident before the detectors has done his job.
6. Detectors -False ceiling
The detectors are placed below the false ceiling and above the ceiling ( if the ceiling height is more than 80 cm).
7. Effectiveness of Detectors
The effectiveness of the detectors are affected by the Internal partition of certain heights, Air Conditioning and Ventilating system,
8. Additional provisions
Additional provisions of protection to be provided in Electric cable tray and trenches, Rack storage, other features like lift shafts, stair wells, utility shafts.
9. Auxiliary systems
Auxiliary systems are additional fire alarm system meant for fire department. A manual pull station or pull boxes are placed under the location of authority and constantly monitored and each such pull boxes or stations has address decoded ,so that local authority can understand the location of the incident and act accordingly.
10. Public Address System
The public address system are used along with the FAS, to make announcements during fire emergencies. It is independent of any other types of PA system uses in the building. Built in Microphones, amplifiers, speakers and change over switch and loud speakers shall form
part of the control and instrumentation panel.
11. FACP
Fire Alarm control panel ( FACP) can be addressable or conventional type
In conventional system ,a zone consists of approx.- 20 no of detectors connected to the fire alarm panel on a 2 core cable.
But in addressable type system, 198 No of intelligent devices are connected on a 2 core cable to the fire alarm.
The detectors can be grouped into the zones. Annunciation of the fire alarm in conventional system is based on the zone basis,while in the
case of addressable type, it is device based, since every device has a unique address in addressable system.
12. Fire Alarm Annunciator Panel
The annunciator panel, is separated from the Fire alarm control panel and is placed in that location of the building, where facility staff can see and be waware of the incident and the incident location. More than one annunciator panel, can be connected to the same system,so that
at it can give information to different locations such as security room, facility staff room etc.
13. Loop Isolators
The loop isolator module is place at certain intervals on the loop, so that when there is a short circuit, only certain no. of devices are affected while the rest of the devices are functioning. When the short circuit is rectified, the loop isolator automatically closes and restores the power
in the isolated devices of the loop.
