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How Fire Alarm Systems Work
Summary:
To date there are two types of smoke detectors,
Ionization and Photoelectric detectors. Read on how fire alarm systems work
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Have you ever wondered how that little round objects
attached to the ceiling ever detect smoke? We see it every day, yet a vast
majority of us don’t know how fire alarm systems work. While we’re talking of
alarms, do you know that a tiny nuclear reaction takes place within that tiny
cylindrical object 24/7? Come along and we’ll take a closer look on how fire
alarm systems work.
To date there are two types of smoke detectors, and
the most commonly used are the ionization detectors. They are cheap, require
little space, and are far more effective than the other type which are the
photoelectric detectors.
Ionization Detector
Inside the Ionization detector houses a small amount
of Americium-241 and two plates of opposite voltage. The voltage is usually
provided by a cell and all are housed in an air flowing metal chamber. The
actual body of chamber functions as the negative plate and the positive plate
covers the Americium. So what does this element do? The Americium generates
alpha particles. These particles ionize the oxygen and nitrogen atoms of the
air inside the chamber. The event is simply knocking off electrons in the air.
As the electrons are knocked off, the air atom gets positively charged and
attracts to the negative plate, while the electron gets attracted to the
positive plate. Meanwhile, the electrical circuits within the detector senses
if there are no disruptions to the pattern.
Because the chamber is open, air passes through freely
and gets ionized. But when smoke enters this Ionization chamber, it disrupts
the ionization process and the electrical horn within the unit is sounded.
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About Americium-241
This element is radioactive, meaning it produces
radiation. But the amount within the Ionization Detector is considerably small
that the radiation it produces won’t pose harmful effects. Plus, the radiation
emitted is mostly alpha radiation which has the penetration factor of only a
few centimeters. Several inches of air completely blocks it; a paper can
effectively block it. Being housed in a metal cylinder would surely pose no
harm. Still, discarded Ionization Detectors should be disposed properly. After all,
it is still a radioactive element.
Photoelectric Detectors
Photoelectric detectors aren’t used as largely because
they aren’t that sensitive as most require a substantial amount of smoke to go
off. Photoelectric detectors consist of two channels, one is to emit light and
the other detects it. If smoke particles are present in the air, this will
interfere with the signal and the alarms goes off.
Most fire alarm systems are wired together so if one
gets an alarm, all fire systems goes off. Some are even wired together with a
water shower that automatically goes off in case of fire.
With my best wishes