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Fire Alarm Systems

Types of Applications: 

• Office Buildings and Shopping Centres
• Computer and TeleComm Centres
• Stand-Alone Strip Malls
• Parking Facilities (interior and exterior)
• Educational and Institutional Facilities
• Retail Tenant Fit-Ups
• Restaurant and Food Establishments
• Factories and Warehouses

• To notify occupants of a fire condition in order to:
• begin evacuation procedures
• begin implementation of fire emergency procedures
 
• To notify the local Fire Department

• To initiate ancillary functions:
• shut-down of air-handling equipment
• release of door hold-open devices
• release of door magnetic-lock devices (mag-locks)
• close fire dampers
• start smoke-exhaust systems
• emergency elevator recall
  

This is the 'brains' of any fire alarm system. All the system components are wired back to the logic circuits within this unit. Based on a pre-programmed set of instructions, the FACP delegates the actions that must be taken once a fire condition signal is received. The FACP is responsible for initiating the fire alarm bells, calling the Fire Department, releasing electric door hardware, and shutting down air-handling equipment that could feed fresh air into a fire. FACPs come in two basic types:

(a) Single-Stage
 

A single-stage FACP will receive a signal from a fire detector or a manual pull-station and will signal the fire alarm bells and perform the required ancillary functions immediately. Most fire alarm systems are of this type.
 
(b) Two-Stage
 
In a two-stage FACP, a signal from a fire detector or a manual pull station will automatically place the fire alarm system into alert or first-stage condition, causing the fire alarm bells to ring intermittently. In this first stage, a qualified security or maintenance person(s) must verify if there is a fire condition and must either cancel the alert, or place the fire alarm system into alarm or second-stage condition, causing the fire alarm bells to ring normally and all the ancillary functions to be performed. The system is put into alarm condition by triggering key-switches located within every manual pull station and at key stations located throughout the building. In the event that a fire condition is neither canceled or confirmed, the FACP will automatically move to alarm condition after a pre-specified length of time (typically 3-5 minutes).
 
Two-stage systems are used in 24-hour manned buildings and where the evacuation of all the occupants would be very difficult and impractical unless the emergency was deemed to be real. This would include hospitals, homes for the aged, some schools, large office buildings, labs, and similar buildings.
 
In addition to these two types of FACPs, there are normal hard-wired systems and addressable fire alarm systems. The latter use telecommunications wiring to connect all the initiating devices to the FACP via a LAN-type network. The flexibility of this type of system is invaluable, providing fire-fighters with the ability to identify the exact initiating device within a particular zone from the FAAP - something not possible with hard-wired systems.  Although an addressable FACP is more expensive, the wiring and labour costs are reduced so that the installed system is almost identical. Axiom Engineering can help your client decide on the best system for his building.
 

The FAAP must be located at the main entrance to the building in plain sight. The FAAP is essentially a signal panel with LEDs and a graphical plan of the protected area that indicates the location(s) in which fire detectors have been initiated. The FAAP is connected directly to the FACP and serves to inform fire-fighters of where fire(s) have broken out. There are also different types of FAAP.
 
(a) Passive Graphic
 
With this type of annunciator, a floorplan of the protected areas is mounted within a frame indicating the different fire alarm zones.  The graphic is mounted beside the FAAP which contains LEDs that correspond to the fire alarm zones - allowing the fire-fighters to see which zone(s) have initiated an alarm condition.
 
(b) Active Graphic
 
An active graphic annunciator also consists of a floorplan of the protected areas indicating the fire alarm zones. However, with this system, an LED or neon lamp is located within the graphic to physically indicate which portion of the building is in alarm condition. This prevents the fire-fighters from having to cross-reference the FAAP LED label with the passive graphic floorplan. With some active graphic systems, it may be possible to illuminate the exact location of the initiating device on the graphic floorplan, leading fire-fighters to the exact point of the fire.
 

In order for a fire alarm system to detect the presence of a fire condition, it must receive a signal (or lack of signal) from a device. There are a variety of initiating devices used in a typical fire alarm system - these represent the most common:

(a) Manual Pull Station
 
This is the familiar tear-drop shaped device that is mounted on walls at exit doors and stairs. Manual pull stations can come equipped with protective covers and cages to prevent accidental and/or vandal tripping. The two-stage version of this initiating device has a built-in key-switch that can be closed to activate the alarm stage.
 
(b) Heat Detectors (a type of fire detector)
 
These inexpensive devices detect temperature levels and can be selected as fixed-temperature units or rate-of-rise units that trigger when an increase in temperature occurs faster than a pre-specified amount of time, indicating an abnormal condition. Heat detectors are not considered as life safety devices and are to be used for property protection only since their response time is relatively slow.
 
(c) Smoke Detectors (a type of fire detector)
 
More expensive than heat detectors, these units are designed to detect the products of combustion and are very sensitive to smoke. As a result, these units are considered as life safety devices. These units come in two basic technology configurations whose use depends on the application. Smoke detectors also come in Duct-Mounted configurations to detect the presence of smoke within ductwork to shut-down the air-handling system and to close fire dampers as required.
 
• Photo-Electric Sensor

 
Using an LED transmitter and receiver within the smoke chamber of the detector, products of combustion are detected as a result of particulates impairing the path of light from the LED source to the receiver. The amount of reduction in light represents the relative quantity of particulates in the atmosphere.
 
• Ionization-Type

 
This unit works similar to the photo-electric units except that rather than containing a light flow within the smoke chamber, a radioactive source is used. The radio-isotope source emits a steady stream of radiation at an exact rate over a period of several years. Any change in that rate would indicate the presence of particulates in the smoke chamber. Due to the natural decay of the radio-active source, these units should be replaced on a regular scheduled basis.
 
Most residential smoke alarms use this technology - care must be taken when disposing these units.