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Description

A smoke detector is a device that detectssmoke, typically as an indicator of fire.Commercial, industrial, and mass residentialdevices issue a signal to a fire alarm system,

while household detectors, known as smokealarms, a smoke alarm is often powered onlyby a single disposable battery.

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Design

Smoke Detector system can be classifiedby manufacturing Technology.

1. Optical2. Ionization3. Air-sampling4. Carbon monoxide and carbon

dioxide detection

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Optical

An optical detector is a light sensor. Whenused as a smoke detector, it includes alight source (incandescent bulb or infraredLED), In the absence of smoke, the lightpasses in front of the detector in a straightline. When smoke enters the optical

chamber across the path of the lightbeam..

A wall-mounted unit sends a beam, whichis e received by a separate monitoringdevice or reflected back via a mirror. Whenthe beam becomes less visible to the "eye"of the sensor, it sends an alarm signal tothe fire alarm control panel.

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Ionization

An ionization type smoke detector isgenerally cheaper to manufacture than anoptical smoke detector; however, it issometimes rejected because it is moreprone to false (nuisance) alarms thanphotoelectric smoke detectors. It can detectparticles of smoke that are too small to bevisible.

Also these alarms are somewhat prone tonuisance alarms because small particles

such as kitchen or cooking smoke mayactivate the alarm.

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Air-Sampling

An air-sampling smoke detector iscapable of detecting microscopic particlesof smoke. Most air-sampling detectors areaspirating smoke detectors,

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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.

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Performance Differences

Optical or "toast-proof" smoke detectors areoften considerably quicker in detectingparticulate (smoke) generated in thesmoldering (cool, smoky) stage of a fire.

Ionization smoke detectors are usually onlymarginally quicker in detecting particulate(smoke) generated in the flaming (hot)stage of a fire.

Only photoelectric smoke detectors areregarded as suitable for detecting fire inboth the smoldering and flaming stages.

Typical smoke detector obscuration ratings

Type of DetectorObscuration Level

Ionization2.65.0% obs/m (0.81.5% obs/ft)

Photoelectric 6.513.0% obs/m (24% obs/ft)

Beam 3% obs/m (0.9% obs/ft)

Aspirating 0.00520.5% obs/m (0.00156.25% obs/ft)

Laser0.066.41% obs/m (0.022.0% obs/ft)

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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 morethan a household smoke alarms.

They exist in most commercial and industrial facilities, such as high rises,ships and trains.

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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.

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Addressable

Analog addressable detectors

provide information about the

amount of smoke in their detection

area.

These are usually more expensivethan autonomous deciding

detectors.

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Batteries

Most residential smoke detectors runon 9-volt alkaline or carbon-zinc batteries.When these batteries run down, the smokedetector becomes inactive.

Common NiMH and NiCd rechargeablebatteries are use in smoke detectors.

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Installation & Placement

Installation and placement processof the Smoke detector is so easy.

In the High rise building, shoppingmall, Convention Center aregradually install the smoke detectorfor Public security..

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Benefits of Installing Smoke Alarm in

the House

1.Early detection can save lives. . It is also valuable in the safety of yourhome. 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 smokeis detected. This will enable you to find out the flame

3. The device will notify everyone in the family right away. There are alsodevices that you can connect with the local rescue unit so that they canrespond right away as soon as your alarm system sounds.