Fire Detection Technologies Fire Detection Technologies

Fire Detection Technologies Fire Detection Technologies
Fire Detection Technologies
A Complete Review
Course Outline
 What is Fire ?
 How do we detect Fire ?
 Construction Challenges
 Future Detection Technologies
 Application Solutions
 The Saving of Lives
CFAA Ontario - 2012 ATS
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What is Fire?
Fire Principles
For a fire to break out, combustible material (fuel)
and an oxidation agent (usually oxygen) must be
available. Our environment is to a large extent made
up of combustible materials – and oxygen is virtually
always sufficiently available. But another condition
must be fulfilled for a fire to break out: The ignition
energy (heat) must be the driving force to initiate
oxidation. Ignition energy sources are manifold:
Electrical discharge (e.g. lightning), short-circuits,
flying sparks, hot surfaces (light bulbs, heating
equipment, etc.), direct exposure to flames or
bundled light, to name only the most important ones.
If a fire occurs, it provides the necessary energy to
maintain the combustion process.
CFAA Ontario - 2012 ATS
The Fire
Page 4
Stages of Fire Development
Incipient stage: Little visible smoke occurs, but especially invisible aerosols are generated.
Smoldering stage: In this phase, the fire can be extinguished by means of a fire extinguisher or a
similar extinguishing agent. Visible, partly dense smoke occurs. Usually, combustion is incomplete, which
is why rather a lot of (toxic) CO is produced in this phase.
Flaming stage: We are faced with an open fire to be fought by the fire brigade. As enough energy is
available, the combustion process is rather complete, resulting in a high production of CO2.
Heat Stage or Flashover: This is the explosive fire spread, taking place exactly at the point when the
gases and aerosols produced during the previous phases ignite and carry the fire into all rooms already
penetrated by the smoke gases.
CFAA Ontario - 2012 ATS
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Products of Combustion
Throughout the various
stages of fire
development and the
types of fuel loads
consumed it is important
to select the most
appropriate detection
technology for the
expected fire.
Frequently the design
parameters require
different technologies to
accomplish the goal of
fast and reliable fire
Open fires (flaming fires)
Smoldering fires (non-flaming fires)
Type of fire
Glowing fires
Solid matters
(mostly emberforming fire)
Liquid matters
Combustion process
Not independent,
requires continuous
energy supply
Independent after
Independent after
Independent after
Independent after
Type of smoke (aerosol)
Very light smoke
Light smoke
Dark smoke
Very dark smoke
and fire phenomena
Optical properties of smoke
Quickly spreading
Quickly spreading
Strongly absorbing,
spreading little
Aerosol volume
UV / IR radiation
Heat convection
Depending on the
carbon share of the
Strongly absorbing,
gas, its chemical
spreading little
properties andmixing
with oxygen
High (except pure
alcohol: none)
Stages of Fire Development
Low to medium
Increases with
Low to medium
Combustion gases
Much CO, little
Much CO, little
Little to much CO,
much CO2
Little CO, much
Little CO, much
None to much
None to much
None to much
Pressure increase
Lowto medium,
depending on the
Low to high, dep.
on fire phenomenon
CFAA Ontario - 2012 ATS
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How do we detect Fire?
Heat Detection
Spot Smoke Detection
Beam Smoke Detection
Duct Smoke Detection
Aspirating Smoke Detection
Flame Detection
Heat Detectors – fixed temperature snap disc
Bifurcated leaf
CFAA Ontario - 2012 ATS
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Heat Detectors – Rate of Rise & Fixed Temp.
Combination detectors have both fixed and rate-of-rise
 The fixed element is generally a non-restorable type,
and when activated, must be replaced.
 The rate-of-rise element is restorable when conditions
return to normal.
Alarm Contacts
Rate of Rise Vent
Rate of Rise Diaphragm
Fixed Heat Collector
Fixed Actuator
Eutectic Solder
(thermal lag)
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Rate Compensation Detector
Rate Anticipation Detector
Fixed Temperature only
Not Subject to Thermal Lag
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Spot Smoke Detection – Ionization
Principle of Detection – Changes in Conductivity
 241 Am – (Americium 241) source of alpha particles
 Half-life of 241 Am is 432.2 years
 Alpha particles are emitted to create current flow
 Emitter and collector electrodes measure changes
 Smoke particles absorb alpha particles and reduce
current flow to create an alarm
Application Notes
 Detects fire in the incipient stage – small
invisible smoke particles
 Detects particles < 3 microns in size
 More unstable at higher airflows
 Requires proper safe disposal procedures
CFAA Ontario - 2012 ATS
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Spot Smoke Detection – Photoelectric
Principle of Detection – Light Extinction
 Infrared LED light source – constant signal
 Smoke entering the chamber absorbs and
scatters light – signal is reduced
 Suitable for all fires producing visible smoke
 Poor maintenance produces false alarms
Principle of Detection – Light Scattering
 Infrared LED light source – blocked by labyrinth
 Smoke entering the chamber and scatters light,
hits the receiver and produces a signal
 Forward scatter detectors suitable for suitable
for smouldering fires with light smoke
 Backward scatter detectors can be better
balanced and made suitable for light or dark
Poor maintenance produces false alarms or
… puts detectors to “Sleep”
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Multi-sensor (Element) Detector
2 or more sensors in a single
package (independent)
Not true Multicriteria
 Most commonly optical smoke sensor with a
heat detector
 Smoke sensors (Scattered light, extinction,
laser, ionization)
 Heat sensors (fixed, rate of rise, rate
 Gas sensors (CO, CO2)
 Optimize performance of each sensor
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Fire Detection Fuzzy Logic
Is this a real fire or a false phenomenon
How do you tell the difference? - When does a boy become a man?
CFAA Ontario - 2012 ATS
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True Multi-Criteria Fire Detection
What we know about fire
- Products of combustion?
The environment
- POC normally present?
- What will be burning (fuel)?
The signals
- The change in signals
- The rate of change in signals
The history of this situation
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Fire Detection Fuzzy Logic
Is this a real fire or a false phenomenon
How do you tell the difference? - When does a boy become a man?
CFAA Ontario - 2012 ATS
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Beam Smoke Detection - Principle
 The emitter sends out a focused light beam. When there is no smoke, this light beam reaches the receiver in
its unattenuated intensity. However, if there is smoke between the emitter and the receiver, the light is partly
absorbed when impinging the smoke particles and partly scattered by them, meaning that it changes direction.
Only a part of the emitted light can reach the receiver. The signal reduction indicates the average smoke
density over the measuring section.
 As the linear smoke detector reacts
on absorption and scattering, it is
suited for light and dark, large and
small aerosols. It is characterized
by its uniform response behavior
and is suited for the early detection
of all fires generating visible smoke.
 Systems accommodating the emitter and receiver in the same housing use a remote reflector and have the
advantage that they need to be connected to the detector line at one point only, and that maintenance is easier.
CFAA Ontario - 2012 ATS
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Open-area Smoke Imaging Detection “OSID”
CFAA Ontario - 2012 ATS
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Duct Smoke Detector – Typical Application
Detector Locations
 Downstream of the air filters and ahead of any branch
connections in the air supply systems having a
capacity greater than 2000 ft3/min.
 At each story prior to the connection to a common
return and prior to any recirculation or fresh air inlet
connection in the air return systems having a capacity
greater than 15,000 ft3/min and serving more than one
Example Detector Installation
Note: The sum of the cross
sectional area of inlet holes MUST
equal cross sectional area of inlet
CFAA Ontario - 2012 ATS
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Aspirating Smoke Detection Principle
Aspirating smoke detectors are
also known as air sampling smoke
smoke detection (ASD). In the air
sampling smoke detection system,
air samples from the monitored
area are guided to the detection
chamber via a pipe network by
detection principle using a laser
providing much less reflected light
under normal circumstances which
maintaining stability.
CFAA Ontario - 2012 ATS
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Aspirating Smoke Detection Sample Layout
Air sampling piping
network provides
inlets which are
spaced as smoke
There is no
reduction needed
for high air flow as
with spot smoke
CFAA Ontario - 2012 ATS
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Linear Heat Detection
Detection Principle – Direct Shorting of Conductors at Specific
Temperatures (350-500 degrees typical)
Manufacturer specific panels can provide approximate locations of
wiring faults to provide point annunciation of the location of alarm.
Wiring Construction
 Steel Conductors are used in a twisted pair to form the Inner Core
 Conductors are wrapped in a heat sensitive polymer to insulate the
them from each other and prevent shorting
 Protective Tape is then used to protect the conductors from
physical damage
 Outer jacket is then applied to protect cable from environmental
conditions specific to the installation
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This system is based on a laser beam being sent through a fiber-optic cable. As the fiber-optic cable reflects a
small part of the laser radiation at any point, the backscatter can be measured by a receiver connected at the
same end as the laser source.
The fiber-optic cable is a doted quartz glass, i.e. a form of silicon oxide (SiO2). The infrared electromagnetic
laser radiation emitted is reflected in different ways by the fiber-optic cable:
− Rayleigh scattering – same frequency
− Raman scattering – Stokes + frequency
− Raman scattering – Antistokes - frequency
The temperature of the fiber-optic cable thus
results from the intensity ratio between
Stokes and Antistokes scattering.
By means of runtime measurements, it is
possible to measure the associated Raman
scattering for each cable spot.
CFAA Ontario - 2012 ATS
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Flame Detector
Principle of Detection – Changes in Radiant Energy
 Detects IR, UV and Flicker Rate of 0.5-15Hz to verify flame
Safe for Class I. Div 1
Hazardous areas
 Calibrated for a 1 sq. ft gasoline pan fire (60, 30, 15 ft selectable)
 Wired and supervised as a 4-wire initiating device (24vdc required)
CFAA Ontario - 2012 ATS
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Detector Response – Summary
The selection of the optimum fire
generated by the incipient fire. For
an office building, smoke detectors
will preferably be selected, as in
this case fires will produce clearly
visible smoke both in the incipient
phase and later. In a storage area
stored, flame detectors and / or
heat detectors would be the right
To be able to reliably detect all expected incipient
fires, it may be necessary to combine different fire
detector types.
CFAA Ontario - 2012 ATS
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Construction Challenges
Construction Challenges
Considerations in product and technology selection
 Accessibility for Maintenance
 Atriums
 Extreme Environments (Temperature, Humidity, Dust, Corrosive)
 Data Centers (High Airflow, Early Warning, Limited Access)
 Hazardous Environments (Class 1 Division 1) Explosion Proof
CFAA Ontario - 2012 ATS
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Future Technologies
RED & BLUE light scattering ASD technology
Distinguishes between large particles that are typical dirt and the small
smoke particles typical in incipient fires better than red infrared based
technology alone.
Discriminates between Smoke & Dust /Steam
CFAA Ontario - 2012 ATS
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Future Technologies – Wireless Detection
Principle – Radio Frequency Transmission
 Utilizing mesh technology wireless smoke detectors
can become integrated into a network whereby the
more detectors exist the stronger the network
becomes. By acting as a transmitter and a repeater,
more detectors create a more robust network that is
more resilient than single detectors alone.
 The detection technology remains unchanged and can
therefore utilize photoelectric or ionization detection
within the same unit.
 This technology is approved for use in the European
market today and will be accepted by both the NFPA
and UL/ULC in the future.
More detectors yield more
communication pathways for better
signal reliability
CFAA Ontario - 2012 ATS
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Future Technologies – Video Smoke Detection
The system concept is to utilize advanced
video analytics to identify smoke or flame
utilizing either existing CCTV cameras or
specialized devices.
The video signals are run through a software
program that processes the change in pixels
to determine alarm status.
This technology is recognized by NFPA 72
as an alternative provided the specific
devices are listed for the purpose.
No ULC standards for this yet.
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Gas Sensors come into their own
The original smoke detector was a failed gas detector
1970’s Cerberus developed a CO sensor, did not catch on in the market
2003 studies by industry researchers explored the use of gas sensors (CO and
CO2) in the fire detectors. Initial feasibility studies indicated a substantial
reduction in nuisance alarms were possible while maintaining a good response
time to fires as compared to smoke detection
Today several manufactures including System Sensor, Bosch, Siemens and
Simplex have commercially available multi criteria smoke detectors where one of
the sensors is a CO gas sensor
Including an array of gas sensors within a smoke detector begins to
approximate an “artificial nose”.
We are just seeing the beginning of the “gases”…
CFAA Ontario - 2012 ATS
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The Future –
To go where Smoke Detection has not gone before
Likely path
Further development to improve the intelligence of smoke detectors,
primarily to discriminate between fire and nuisance sources, but also
perhaps to discriminate between fire sources
Intelligence can also bring information from an array of smoke detectors
to feed a panel to chart the recent course of the fire and direct people to
exits away from the fire or heavy concentrations of smoke …
maybe this could be called “Intelligent Response” to an emergency
CFAA Ontario - 2012 ATS
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The Future –
To go were Smoke Detection has not gone before
Going further into the future
Having a recent history of fire conditions
within a space may enable future conditions
to be predicted through the use of a reverse
algorithm. This would involve using the
detector measurements to infer the
characteristics of a fire source, e.g. heat
release rate, location, fuel etc. These
characteristics can then be used as input to
enable the use of a computer fire model to
predict the future course of the fire.
Audio Analytics?
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Application Solutions
Application Solutions
 Spot Smoke Detection
 Duct Smoke Detection
 Aspirating Smoke Detection
 High Airflow Data Rooms
 High Humidity and Condensation
 Amusement Park Rides (limited access)
 Atriums
 Spot Heat Detection – Rate of Rise w/ Fixed Temp
 Linear Heat Detection – Thermal / Optical Fibre
 Long runs
 Limited access
 Extreme environments
 Multiple applications
 Flame Detection – IR & UV with Flicker verification
 Beam Detection – Open-area Imaging Smoke Detection
CFAA Ontario - 2012 ATS
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Challenging Environments for Fire Detection
Finding the right solution may
require multiple technologies
Manufacturing Plants
Cold Storage Warehouses
Select a vendor who can apply the best solution
to meet the challenge
Textile Mills
CFAA Ontario - 2012 ATS
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The Saving of Lives
The Saving of Lives
Since 1970 Smoke Detection has contributed
to saving an estimated 90,000 lives
Early 1900’s
15,000 people per year die in FIRES
8,500 people per year die in FIRES
3,300 people per year die in FIRES
CFAA Ontario - 2012 ATS
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