AG FIRE

Active Fire Protection

Active fire protection systems are an extremely important part of protecting property and the lives of the people within. An important factor that active fire protection systems share is that they involve action of some kind and ensures the alarms will function properly in the event of an emergency. Some examples of these actions include notifying of fire and smoke conditions, or slowing the progress of fire, or putting out the fire.

Active fire protection systems such as fire detection & notification systems, water sprinkler and spray systems are normally a mandatory requirement for rail & air transport terminals, high-rise buildings, schools, hospitals, and other large facilities. The duties of the fire protection system are basically detection, notification and extinguish the fire, control the fire, or provide exposure protection to prevent domino effects. For some specialised applications, systems like foam pourers or using inert gases or halogen based gases are used for flooding enclosed spaces, may be a more appropriate method of delivery than sprays or sprinklers.

- Fire Detection System (+ Click to expand)

The fire is detected either by locating the smoke, flame or heat, and an alarm is sounded to enable emergency evacuation as well as to dispatch the local fire department. Where a detection system is activated, it can be programmed to carry out other actions which include AHU tripping, de-energising magnetic hold open devices on Fire doors and opening servo-actuated vents in stairways.

- Spot-Type Detectors (+ Click to expand)

- Optical Smoke Detector

An Optical Smoke Detector includes a light source, a lens to collimate the light into a beam, and a photoelectric sensor at an angle to the beam as a light detector. In the absence of smoke, the light passes in front of the detector in a straight line. When smoke enters the optical chamber across the path of the light beam, some light is scattered by the smoke particles, directing it at the sensor and thus triggering the alarm. Optical smoke detection is generally more responsive to fires that begin with a long period of smoldering called smoldering fires.

- Heat Detectors (+ Click to expand)

A heat detector is a fire detection device similar to a smoke detector; however it is more resistant to false alarms in areas with a large amount of dust and debris. Since it does not detect smoke, it is therefore not meant as a replacement for a smoke detector. In fact, this type of sensor is used to detect changes in ambient temperature; alarms are triggered when the temperature gets too hot. There are two types of heat detectors on the market today:

- Fixed Temperature

Fixed Temperature type heat detector makes use of a metal alloy. When the ambient room temperature exceeds the specified temperature for that particular device; the alloy melts and in turn give rise to an alarm. Normally the fixed temperature for these detectors is 115°F to 135°F. It is important to replace this type of heat detector once an alarm has been triggered; if the metal alloy melts, the detector is worthless.

- Rate of Rise

Rate of Rise type heat detector employs a sensing component; used to detect rapid or slow/steady increases in the ambient room temperature. This type is slightly more sensitive than the fixed temperature detector. This type of heat detector can detects sudden & abrupt change in temperature and also observes a 12°F to 15°F increase per minute within the room. This “rate of temperature increase” can be programmed as per room conditions.

- Multi Sensor Smoke Detector

Multi Sensor Smoke Detector incorporates two detection types into a single unit; it features both an optical smoke detection and a heat detection. It’s important to understand that not all fires are the same. Some, for example start off slow and smouldering and produce more smoke and relatively little flame at first; this would be picked up by a Smoke detector but not so easily by a Heat detector. On the other hand, fast flaming fires with a corresponding fast rise in temperature would very probably set off a Heat detector before a Smoke detector. By combining the two, a Multi-Sensor offers the best – and crucially the fastest - possible warning if there is a fire.

- Aspirating Smoke Detector (+ Click to expand)

An Aspirating Smoke Detector (ASD), consists of a central detection unit which draws air through a network of pipes to detect smoke. The sampling chamber is based on a nephelometer that is capable of detecting the presence of smoke particles suspended in air by detecting the light scattered by them in the chamber. ASD system to provide very early warning of an event, prompting investigation at the earliest smouldering stage of a fire when it is easily addressed. Aspirating smoke detectors are highly sensitive, and can detect smoke before it is even visible to the human eye.

ASD design corrects shortcomings of normal smoke detectors by using sampling pipe with multiple holes. The air samples are captured and filtered, removing any contaminants or dust to avoid false alarms and then processed by a centralized, highly sensitive laser detection unit. If smoke is detected, the systems alarm is triggered, and signals then are processed through centralized monitoring stations within a few seconds. Other alarm levels may be configured to provide fire alarm inputs to fire systems as well as releasing suppression systems. ASD alarm sensitivities are configurable and can be programmed to levels ranging from thousands of times more sensitive than a normal detector, to much less sensitive.

ASDs are suitable for environments where a highly sensitive rapid smoke detection capability is required. This makes them suitable in clean rooms; areas which contain goods easily damaged by fire, such as tobacco, electronic rooms and highly flammable liquid and gases. Often, normal point detectors will recognise the danger too late, as smoke often does not reach the ceiling quick enough for a fire to be detected in a timely fashion. Most ASD products can accommodate a broad range of environments and applications – from both confined and open spaces to the cleanest or dirtiest environment, including telecomm, control rooms, waste treatment, mining and more.

- Linear Heat Detection System/Cable
(+ Click to expand)

The Linear Heat Sensor Cable is used as a detection device in Fire Detection & Alarm Systems. The Linear Heat Sensor Cable is effectively used to operate within areas of limited access and surveillance and within environmental conditions that would render other forms of detection, inoperable or subject to high levels of costly maintenance or false alarms.

The linear heat detection uses a single pair heat sensitive cable as the basis for its overheat/fire detection system. At a pre-selected temperature, the thermal sensitive polymer softens, allowing the signaling cores/ conductors - that are twisted together to form a spring like pressure between them - to move into contact with each other producing an alarm signal. A mechanical tension is constantly and uniformly maintained along the entire length of the detector. If conductor continuity is broken – with inner insulation maintained an open circuit fault condition will be signaled.

An outer extrusion of corrosion and abrasion resistant polymer maintains the conductor twisting over the full length of sensor cable installed and allows for its installation in external weather conditions and its application within more severe local environments. The authority having jurisdiction should always be contacted to confirm suitability of specified alarm temperature rating. It is advisable to allow a minimum of +11°C/+20°F between maximum normal ambient and minimum alarm temperature in order to avoid any potential false alarm conditions. Typical applications includes Cable Tunnel / tray protection, Road / Rail Tunnels, Rail Stations, Aircraft Hangars, Warehouses, Power distribution, Escalators & Elevators / Lifts etc.

- Fire Notification System (+ Click to expand)

A fire alarm notification appliance is an active fire protection component. A notification appliance may use audible, visible, or other stimuli to alert the occupants of a fire or other emergency condition requiring action. The primary function of the notification appliance is to alert persons at risk.

Sound (Audible Signal) appliances produce sound pressure levels between 45 and 120 decibels at ten feet

Light (visual signal) appliances with 15 cd to 1000 cd candela output

Voice evacuation systems (also called Voice Alarm Systems) gives a voice message warning that an emergency has been reported and also gives directions to occupants to evacuate the building. Voice evacuation systems can also be used by personnel to give specific live information and/or instructions over the alarm system, which provides a distinct advantage over horns or bells.

- Fire Suppression Systems(+ Click to expand)

This may be to extinguish the fire, control the fire, or provide exposure protection. Types of fire fighting media are:

Water - Water is not recommended as an extinguishing media for low flash point liquids, but it is used widely throughout industry for fire control and exposure protection.

Foams - Foam is a more effective extinguishing media for low flash point substances and is widely used against liquid fires. There are various types of foam available, but the most widely used is protein foam. Alcohol resistant foam is used for application on polar solvents where the foam stability is affected. Other more specialist foams have been developed to give improved extinguishing properties such as fluoro-protein and aqueous film forming foams. Foam can be delivered as low, medium or high expansion depending on the required duty. Foam is a more effective extinguishing media for low flash point substances and is widely used against liquid fires. There are various types of foam available, but the most widely used is protein foam. Alcohol resistant foam is used for application on polar solvents where the foam stability is affected. Other more specialist foams have been developed to give improved extinguishing properties such as fluoro-protein and aqueous film forming foams. Foam can be delivered as low, medium or high expansion depending on the required duty.

Inert gases - A common use for these systems is in the protection of switch rooms and control panels.

Chemical powders - A common use for these systems is in the protection of switch rooms and control panels.

Halons - There has been movement away from the use of Halons over recent years due to their potential effect upon the ozone layer and other undesirable environmental effects. (can be removed)

Passive Fire Protection

Passive fire protectionwhich includes compartmentalization of the overall building through the use of fire-resistance rated doors, walls and floors. Organization into smaller fire compartments, consisting of one or more rooms or floors, prevents or slows the spread of fire from the room of fire origin to other building spaces, limiting building damage and providing more time to the building occupants for emergency evacuation or to reach an area of refuge.

Passive Fire Protection measures are intended to contain a fire in the fire compartment of origin, thus limiting the spread of fire and smoke for a limited period of time, as determined the local building code and fire code. Passive fire protection measures, such as fire-resistance rated smoke curtains, fire curtains, fire doors, and fire walls, usually expressed in terms of hours of fire resistance.

- Fire Door (+ Click to expand)

A fire door is a door with a fire-resistance rating used as part of a passive fire protection system to reduce the spread of fire or smoke between compartments and to enable safe egress from a building or structure. Rated fire doors are tested to withstand a fire for a specified period of time.

Most fire doors are designed to be kept closed at all times. Some doors are designed to stay open under normal circumstances, and close automatically in the event of a fire. Whichever method is used, the door's movement should never be impaired by a doorstop or other obstacle. The smoke-seal bounding of fire doors should be routinely checked, as should the action of the door closer and latch. Some fire doors are held open with an electromagnet, which may be wired to a fire alarm system. If the power fails or the fire alarm is activated, the coil is de-energized and the door closes on its own.

- Fire Curtain (+ Click to expand)

A fire curtain is a specially developed and engineered screen that drops from the ceiling and literally cuts off the path of a fire between two open areas, very much like a traditional fire door. In case of fire break out, the curtains will lower into position without haste. Once in place up to two hours of premium protection can be provided by the curtains. This should be more than enough time for the fire to be controlled and the staff members given the chance to escape. Intelligent systems can be used to create instant and secure fire escape corridors throughout a building.

- Smoke Curtain (+ Click to expand)

A smoke curtain is a specially developed and engineered screen that drops from the ceiling and is designed to channel toxic fumes to a safe exit point in a building. Unlike a fire curtain, a smoke curtain does not need side guides and normally, does not always need to drop to floor level.