Fire Alarm and Detection: Zoning Systems

smoke alarmThe smoke and heat detectors installed in homes can be looped together and connected to the control and repeater panels, using any of the two standard zoning systems. Zoning simply means dividing the detectors into several groups or sections, where each group is separate and distinct from another group.

Types of Zoning Systems

1. The Conventional Zoning System
This is used for small to medium-size residential buildings. In the conventional system, each floor is regarded as a zone for buildings having more than one floor. In the event of a fire outbreak, the panels indicate the zone in which the fire is occurring. A major drawback of this system however, is its inability to indicate the exact location of the fire in the zone. It gives a general, rather than a particular location.

2. The Addressable Zoning System
The addressable zoning system is employed mainly for very large estates and high-rise commercial buildings. In this system, the zones or groups are designed and created in such a way that the exact location of the fire can be known. In the event of a fire outbreak, the panels inform the building occupants of the particular detector issuing the alarm and thus, the precise location of the fire can be inferred.

Why The Addressable System is Preferred to the Conventional System?

Cost
Conventional zoning systems have low purchasing costs and very high installation costs. They require more wires and additional labour time during installation. Addressable zoning systems, on the other hand, have higher purchasing costs and very low installation costs. They also have additional features that help in preventing false alarms which are quite costly to the owner of the building.

Ease of Installation
Installation of conventional zoning systems are more difficult, expensive and time consuming, when compared to the addressable zoning system.

Reliability
The addressable zoning system is more reliable than the conventional zoning system. In the addressable system, isolation modules are used to separate detectors in a loop or zone. Thus, if a detector gets disconnected, the other detectors in the loop continue functioning. The proper installation of an addressable panel can lead to the overall reliability of the fire alarm and detection system.

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Complexity
The addressable zoning system is superior to the conventional system in terms of complexity. While the conventional zoning system is pretty simple and executes basic fire alarm and detection functions, the addressable zoning system is more compels and sophisticated, having additional features and functions.

Addressable zoning systems are very flexible and powerful when used properly. However, it is important to note that the choice of zoning system to be used is actually dependent on a lot of factors. The consumer or home owner has to consider the following before deciding on the zoning system to purchase and install: the type and size of the building, the installer, the cost and the budget, the level of security needed, among others. Whatever zoning system chosen must be able to suit the needs of the home and its owner.

Fire Alarm and Detection: Smoke and Heat Detectors

Home security is not only concerned with preventing burglary and other criminal attacks on the home, it also involves the safeguarding of lives and properties in the home against fatal accidents such as fire outbreaks. A fire alarm and detection system is designed to detect fire outbreaks in buildings and send out an identifiable alarm to the concerned parties. The system consists of smoke detectors, heat detectors, control and repeater panels, alarm bells and break glasses.

What Are Smoke Detectors?

Smoke detectors are devices capable of detecting or sensing smoke and signalling a warning to either the homeowner or the fire authorities, depending on the manner in which it was programmed. There are basically two types of smoke detectors: ionization and photoelectric smoke detectors.

ionization-detectorThe ionization detector uses the theory of electric circuit as its operating principle. The ions and electros in the chamber of the detector move between two electrodes, thus creating an electric current. However, during a fire outbreak, smoke particles attach themselves to the ions and the current ceases to flow. Once this happens, the sensor is tripped and the home owner alerted.

photoelectric-smoke-detectorIn the photoelectric or optical detector, a beam of infrared or ultraviolet light is emitted and reflected back. If the intensity of the light reflected back is lesser than the light emitted, due to smoke or other air-borne substances absorbing part of it, the smoke sensor is tripped and the alarm alerts the owner.

Comparisons Between Optical and Ionization Smoke Detectors

1. The ionization smoke detector is cheaper than its optical counterpart.

2. Ionization smoke detectors are more prone to false alarms than the optical ones.

3. Optical smoke detectors are more responsive to smoldering fires than blazing flames, while ionization smoke detectors respond faster to blazing 4. The optical smoke detector is more reliable for detecting smoke at both the smoldering and flaming stages of fires.

5. Optical smoke detectors are less likely to be mistakenly deactivated by the home owner.

On the whole, fire safety experts and authorities advise home occupants to purchase optical (photoelectric) detectors, as they are more effective than the ionization detectors. Combination detectors that use both the ionization and photoelectric processes are also recommended.

Smoke detectors should be installed in every bedroom and hallway. They should not be placed in the bathrooms, toilets, kitchens, laundry room and the garage. One smoke detector is sufficient for each room, as long as the room’s area is less than 100m 2 . Once the area of the room is equal to or greater than 100m 2 , then two smoke detectors are placed in the room.

What Are Heat Detectors?

These are devices that detect or sense a change in temperature in a space and alert the concerned parties. Heat detectors are placed in rooms or spaces where there would naturally be smoke or mist, such as kitchens, enclosed car parks, bathrooms and toilets, laundry rooms, garages and generator houses.

For ideal residential fire protection, the combination of smoke and heat detectors is recommended.