SMOKE DETECTOR

[seminar class]

PRESENTED BY:
Nanda Dulal Maity

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SMOKE DETECTOR
 Description
A smoke detector is a device that detects smoke, typically as an indicator of fire. Commercial, industrial, and mass residential devices issue a signal to a fire alarm system, while household detectors, known as smoke alarms, a smoke alarm is often powered only by a single disposable battery.
 Design
Smoke Detector system can be classified by manufacturing Technology.
1. Optical
2. Ionization
3. Air-sampling
4. Carbon monoxide and carbon dioxide detection
 Optical
An optical detector is a light sensor. When used as a smoke detector, it includes a light source (incandescent bulb or infrared LED), 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..
A wall-mounted unit sends a beam, which is e received by a separate monitoring device or reflected back via a mirror. When the beam becomes less visible to the "eye" of the sensor, it sends an alarm signal to the fire alarm control panel.
 Ionization
An ionization type smoke detector is generally cheaper to manufacture than an optical smoke detector; however, it is sometimes rejected because it is more prone to false (nuisance) alarms than photoelectric smoke detectors. It can detect particles of smoke that are too small to be visible.
 Also these alarms are somewhat prone to nuisance alarms because small particles such as kitchen or cooking smoke may activate the alarm.
 Air-Sampling
An air-sampling smoke detector is capable of detecting microscopic particles of smoke. Most air-sampling detectors are aspirating smoke detectors,
 Carbon monoxide and carbon dioxide detection
Some smoke alarms use a carbon dioxide sensor or carbon monoxide sensor in order to detect extremely dangerous products of combustion.
 Performance Differences
Optical or "toast-proof" smoke detectors are often considerably quicker in detecting particulate (smoke) generated in the smoldering (cool, smoky) stage of a fire.
Ionization smoke detectors are usually only marginally quicker in detecting particulate (smoke) generated in the flaming (hot) stage of a fire.
Only photoelectric smoke detectors are regarded as suitable for detecting fire in both the smoldering and flaming stages.
 Commercial smoke detectors
Commercial smoke detectors are two types
 Conventional
 Analog Addressable
These are the most common type of detector, and usually cost a lot more than a household smoke alarms.
They exist in most commercial and industrial facilities, such as high rises, ships and trains.
• Conventional
These detectors are connected in parallel to the signaling path.
The resulting increase in current flow is interpreted and processed by the control unit as a confirmation of the presence of smoke and a fire alarm signal is generated.
• Addressable
Analog addressable detectors provide information about the amount of smoke in their detection area.
These are usually more expensive than autonomous deciding detectors.
 Batteries
Most residential smoke detectors run on 9-volt alkaline or carbon-zinc batteries. When these batteries run down, the smoke detector becomes inactive.
Common NiMH and NiCd rechargeable batteries are use in smoke detectors.
 Installation & Placement
Installation and placement process of the Smoke detector is so easy.
In the High rise building, shopping mall, Convention Center are gradually install the smoke detector for Public security..
 Benefits of Installing Smoke Alarm in the House
1.Early detection can save lives. . It is also valuable in the safety of your home. Detection of a threat early on will help save lives
2. You can respond to the alarm immediately. You can try to stop the fire from spreading. The detectors will point you to the area where the smoke is detected. This will enable you to find out the flame
3. The device will notify everyone in the family right away. There are also devices that you can connect with the local rescue unit so that they can respond right away as soon as your alarm system sounds.