Fire Alarm Systems are designed
to alert us to an emergency so that we can take action to protect
ourselves, staff and the general public. Fire alarms are found in Offices, Factories, and public
buildings,they are a part of our everyday routine but are often overlooked
until there is an emergency at which point, they might just save our lives. Whatever the method of detection
is, if the alarm is triggered, sounders will operate to warn people in the
building that there may be a fire and to evacuate. The fire alarm system may also
incorporate a remote signal system which could then alert the fire
brigade via a central station. In this video, we will have a look at the
structure and types of the “Fire Alarm Systems”. before we get started on today's video if you love our videos, be sure
to click the like button below. then make sure to click subscribe and the little bell to receive
notifications of new RealPars videos. This way you never miss another one! The “Brain” of the system is
the Fire Alarm Control Panel. It is the central hub for all of the detector signals to
be wired to and provides a status indication to the users. The unit can also be set up to simulate an alarm
for use in routine Fire and evacuation drills, so all staff knows what action to
take in the event of a real fire. At the core of a fire alarm
system are the detection devices, from sophisticated intelligent smoke detectors
to simple manually operated break glass units there are a wide array of different types,
but we can divide them into groups including Heat detectors, Smoke detectors, Carbon Monoxide
detectors, Multi-sensor detectors, and Manual Call Points. A Heat detector can either work
on a fixed temperature basis, where it will trigger an alarm if the
temperature exceeds a pre-set value or they can work on the rate
of change in temperature. Commonly Heat detectors work in a
similar way to an electrical fuse, the detectors contain a eutectic alloy which is heat
sensitive when a certain temperature is reached the alloy turns from a solid to a liquid
which in turn triggers the alarm. There are three basic types of smoke detectors including
Ionization, Light Obscuring, and Light Scattering. An Ionization Smoke detector
generally contains two chambers. The first is used as a reference to compensate for
changes in ambient temperature, humidity or pressure. The second chamber contains a radioactive
source, usually alpha particle, which ionizes the air passing through the chamber
where a current flows between two electrodes. When smoke enters the chamber
the current flow decreases. The drop in current flow is
used to initiate an alarm. The light scattering smoke detector
operates on the Tyndall effect; a photocell and light source are separated
from each other by a darkened chamber such that the light source does
not fall on the photocell. The passage of smoke into the chamber causes the light from the source to be
scattered and fall on the photocell. The photocell output is being
used to initiate an alarm. In the Light obscuring smoke detector, smoke interferes with a light beam
between a light source and photocell. The photocell measures the
amount of light it receives. The variation in photocell output,
is being used to initiate an alarm. This type of detection can be
used to protect large areas with the light source and photocell
positioned some distance apart. Carbon monoxide detectors are
known also as CO fire detectors and are electronic detectors used
to indicate the outbreak of fire by sensing the level of carbon monoxide in the air. Carbon monoxide is a poisonous
gas produced by combustion. In this instance, these detectors are not the same
as carbon monoxide detectors used in the home for protecting residents against carbon monoxide
produced by incomplete combustion in appliances such as gas fires or boilers. Carbon Monoxide fire detectors use the
same type of sensor as those in the home but are more sensitive and respond more quickly. Carbon monoxide detectors
have an electrochemical cell, which senses carbon monoxide, but not
smoke or any other combustion products. The Multi-sensor detectors combine inputs
from both optical and heat sensors and process them using a sophisticated
algorithm built into the detector circuitry. When polled by the control panel the detector returns a value based on the combined
responses from both the optical and heat sensors. They are designed to be sensitive
to a wide range of fires. A Manual Call Point or Break Glass Call Point is a device which enables personnel to raise the alarm by breaking the frangible element on the
fascia; this then triggers the alarm. Fire Alarm Systems can be broken down
into four main types; “Conventional”, “Addressable”, “Intelligent
Fire Systems” and “Wireless Systems”. Let’s spend some time considering each. In a Conventional Fire Alarm System,physical cabling is
used to interconnect several call points and detectors, the signals from which are wired
back to the main control unit. Call points and detectors are arranged in “Zones”
to simplify locating the cause of the alarm, this is important for both the fire
brigade and general building management. Each zone is indicated at the Fire Alarm
Control Panel either with an indicator lamp, a text display or in some cases both. It makes sense that the more we
can divide a building into zones, the more accurate locating
the alarm trigger will be. The Control Panel is wired to a
minimum of two sounder circuits which could contain bells, electronic
sounders or other audible devices. It is these devices which sound
the alarm when triggered. The detection principle
of an Addressable System is the same as a Conventional System except that each detector is given a set
Address usually by means of a dip-switch and the Control Panel can then determine exactly which
detector or call point has initiated the alarm. The detection circuit is wired as a loop and up
to 99 devices may be connected to each loop. It is common for the loop to be
fitted with Loop Isolation Modules so that the loop is sectioned in order to
ensure that a short circuit or single fault will only cause the loss of
a small part of the system. Allowing the rest of the
system to function normally. In the previous two systems, the “Conventional
System” and the “Addressable System” the detectors are not considered “intelligent” as they can only give output signals
representing the value of detected phenomena. It is left up to the Control Unit to decide whether
there is a fire, fault, pre-alarm or other. However, in our next type of System, which
is an Intelligent Fire Alarm system, each detector effectively incorporates its own
computer which evaluates the environment around it and communicates to the Control Panel whether there
is a fire, fault or the detector head needs cleaning. Essentially Intelligent Systems are far more complex and incorporate far more facilities than
Conventional or Addressable Systems. Their primary purpose is to help prevent
the occurrence of false alarms. Intelligent Fire Alarm Systems are
available in 2, 4, and 8 loop versions which means large premises can be
monitored from one single panel. The final type of system we will consider
is the Wireless Fire Alarm System. These are an effective alternative to traditional
wired fire alarm systems for all applications. They utilize secure, license-free
radio communications to interconnect the sensors and
devices with the controllers. It is a simple concept, which
provides many unique benefits and is a full intelligent fire detection
system without the need for cabling. In this video, we have learned that Fire Alarm systems
are fitted in many buildings we encounter every day and that they are used to warn people within the
building of an emergency fire-related situation. We discussed the main types of detectors: Heat Detectors, Smoke Detectors, Carbon Monoxide
Detectors, Multi-Sensor Detectors, and Manual Call points. And finally, we looked at the different
types of fire alarm systems: Conventional, Addressable, Intelligent
Fire Systems, and Wireless Systems. We hope you enjoyed this short
introduction to Fire Alarm Systems, here at RealPars our team of experts is on hand to
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