smoke alert for industries ppt

8/2/2019 Smoke Alert for Industries Ppt

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SMOKE ALERT

FORINDUSTRIES

By:-PRASHANT KUMAR&PRASHANT LAL


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A mechanical device that is sensitive to thepresence of smoke or particulate material in the air

that transmits a signal to a measuring or controlinstrument.

Smoke detectors consist of two basic parts: asensor to sense the smoke and a very loudelectronic horn to wake people up.

screwed to your ceiling always.


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Types of smoke detector

Photoelectric smoke detector

Ionization smoke detector

Aspirated smoke detectors


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Photoelectric Smoke Detector

The photoelectric type of smoke detectorutilizes light as a detection mechanism.There are two basic types of photoelectric

smoke detectors

Light sensing (scattering). Light obscuring (blocking).


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Light scattering smoke detector

Light sensing photoelectric smoke detectorsdepend on the ability of small airborne particlesto scatter light.Scattering is due to absorption, reflection,refraction, polarization, and diffraction.


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the light emitted from the light source is notdetected by the photo sensor.

When smoke particles enter the chamber,some of the light is scattered toward thephoto sensor.

The amount of smoke that enters thechamber increases, more incident light isscattered toward the photo sensor.

When the concentration of particles reaches

a predetermined threshold, an alarm willsound.

Cont.


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Light obscuring smoke detectors

A projected beam photoelectric smoke detector can use asingle light source and photosensor to monitor a very

large area.Use an IR LED or laser diode as a light source.smoke detectors cover 900 sq. ft.


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Detection of smoke by attenuated light.

Uses a separate emitter and detector.

Signals are processed and compared to a

reference level.

When two consecutive signals exceedingthe reference level are received.

Time delay circuit triggers the switch toactivate the alarm signal.


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Ionization smoke DetectorHave ionization chamber inside the detectorIonization chamber is simply two plate chamber withvoltage across them along with radioactive source ofionization radiation.The alpha particles generated by theamericium ionize the oxygen and nitrogen atoms ofthe air in the chamber.


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Ionize means to "knock an electron off" free electron are created.

The negative electron is attracted to the plate witha positive voltage, and the positive atom isattracted to the plate with a negative voltage.

The electronics in the smoke detector sense thesmall amount ofelectrical current that theseelectrons and ions moving toward the platesrepresent.

When smoke enters the ionization chamber, it

disrupts this current. The smoke particles attach to the ions and

neutralize them. The smoke detector senses thedrop in current between the plates and sets off thehorn.

Ionization smoke detector (Cont.)


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Comparison of ionization &photoelectric

Ionization Detects fast, flaming fires

Detects smoke produced by flammable liquids, looselypacked light combustibles, and kitchen grease.

Photoelectric

Effective for slow burning, smoldering types of fires. Detects smoke caused by cigarettes burning in

furnishings and bedding.

A i t d k


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Aspirated smokedetectors

Active detector system.

Central detection unit draws air through a network ofpipes to detect smoke.

The sampling chamber is capable of detecting the

presence of smoke particles suspended in air bydetecting the light scattered by them in the chamber.

The air samples are captured and filtered, removing anycontaminants or dust to avoid false alarms.

ASD systems actively draw smoke to the detector

If smoke is detected, the systems alarm is triggered, andsignals then are processed through centralizedmonitoring unit .


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Architecture

Transmitter

PICMicrocontroller

ToneGenerator

Receiver

SmokeSensor

Temperature Sensor

Low BatterySensor


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System Overview

v Hardware Transmitter (RMX-900-HP3) Receiver (TMX-900-HP3) Tone Generator (LM555CM)

Smoke Sensor (276-142, 279-143) Temperature Sensor (LM235AH) Low Battery Sensor

v Software PIC Microcontroller (C Language)


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PIC

MICROCONTROLLERBlock Diagram


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Temperature Sensor

Temperature threshold of125F reached?

ReceiverRF signal received fromanother detectors

transmitter?

Smoke Sensor

Smoke detected?

Low Battery Sensor

Battery measured below3.5V?

PIC MicrocontrollerTemperature sensor, receiver,smoke sensor, or low batterysensor has been set off?

Transmitter

ToneGenerator

No

Yes

Yes

Always

No

No

Yes

No

Yes


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Importance Deaths occur from breathing in smoke and toxic

gases from a fire, not from being burned by flamesand Poisonous gases created during a fire, likecarbon monoxide, can quickly cause a person tobecome confused and disoriented

Smoke alarms are purposely built to warn and

protect those inside buildings from potential fireaccidents

Playing the Numbers

Night time Fire Safety

Alerts

Invisible Threats


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Statistics show that death or serious injury

can be avoided in households

where smoke alarms are installed andmaintained.

SMOKE ALARMS SAVE LIVES!

PROTECT YOURSELF.


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ANY QUESTION

smoke alert for industries ppt

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