Fire Detection and Alarm
System Basics
Hochiki America Corporation
7051 Village Drive, Suite 100
Buena Park, California 90621
www.hochiki.com
Fire Detection and Alarm Systems
A key aspect of fire protection is to identify a developing fire emergency in
a timely manner, and to alert the building's occupants and fire emergency
organizations.
This is the role of fire detection and alarm systems. Depending on the
anticipated fire scenario, building and use type, number and type of
occupants and criticality of contents and mission, these systems can
provide several main functions:
First, they provide a means to identify a developing fire through either
manual or automatic methods.
Second, they alert building occupants to a fire condition and the need to
evacuate.
Another common function is the transmission of an alarm notification signal
to the fire department or other emergency response organization.
They may also shut down electrical, air handling equipment or special
process operations, and they may be used to initiate automatic
suppression systems.
Fire Detection Principles
Manual Fire Detection - Pull Stations
Manual fire detection is the oldest method of detection. In the
simplest form, a person yelling can provide fire warning. In
buildings, however, a person's voice may not always transmit
throughout the structure. For this reason, manual alarm stations
are installed. The general design philosophy is to place stations
within reach along paths of escape. It is for this reason that they
can usually be found near exit doors in corridors and large rooms.
The advantage of manual alarm stations is that, upon discovering
the fire, they provide occupants with a readily identifiable means
to activate the building fire alarm system. The alarm system can
then serve in lieu of the shouting person's voice. They are simple
devices, and can be highly reliable when the building is occupied.
The key disadvantage of manual stations is that they will not work
when the building is unoccupied. They may also be used for
malicious alarm activations. Nonetheless, they are an important
component in any fire alarm system.
2007 NFPA 72, 3.3.63.3 Manual Fire Alarm Box. A manually operated device used
to initiate an alarm signal.
Fire Detection Principles
Automatic Detectors – Spot type
2007 NFPA 72, 3.3.43.21 Spot Type Detector. A device in which the detecting
Element is concentrated at a particular location. Typical examples are
Bimetallic detectors, fusible alloy detectors, certain pneumatic rate-of-rise
Detectors, certain smoke detectors, and thermoelectric detectors.
Fire Detection Principles
Automatic Detectors – Photoelectric
Hochiki SLR-24V detector
2007 NFPA 72, 3.3.181.4 Light Scattering Smoke Detection. The principle of
using a light source and a photosensitive sensor arranged so that the rays from the
light source do not normally fall onto the photosensitive sensor. When smoke
particles inter the light path, some of the light is scattered by reflection and
refraction onto the sensor. The light signal is processed and used to convey an
alarm condition when it meets preset criteria.
Fire Detection Principles
Automatic Detectors – Photoelectric
In the normal case, the light from the light source on the left shoots straight
across and misses the sensor.
When smoke enters the chamber, however, the smoke particles scatter the
light and some amount of light hits the sensor.
A – Light Source
B – Photo Sensor
Fire Detection Principles
Automatic Detectors – Ionization
Ionization smoke detectors use an ionization chamber and a source of ionizing radiation
to detect smoke. This type of smoke detector is more common because it is inexpensive and
better at detecting the smaller amounts of smoke produced by flaming fires.
Inside the ionization detector is a small amount (perhaps 1/5000th of a gram) of Americium241. The radioactive element americium has a half-life of 432 years, and is a good source of
alpha particles.
An ionization chamber is very simple. It consists of two plates with a voltage across them,
along with a radioactive source of ionizing radiation.
Hochiki SIJ-24 detector
2007 NFPA 72, 3.3.181.2 Ionization Smoke Detection. The principle of using a small amount of
radioactive material to ionize the air between two differentially charged electrodes to sense the
presence of smoke particles. Smoke Particles entering the ionization volume decrease the
conductance of the air by reducing ion mobility. The reduced conductance signal is processed and
used to convey an alarm condition when it meets preset criteria.
Fire Detection Principles
Automatic Detectors – Ionization
Ionization Smoke detectors
The alpha particles generated by the americium have the following property: They ionize the
oxygen and nitrogen atoms of the air in the chamber. To "ionize" means to "knock an electron off
of." When you knock an electron off of an atom, you end up with a free electron (with a negative
charge) and an atom missing one electron (with a positive charge). The negative electron is
attracted to the plate with a positive voltage, and the positive atom is attracted to the plate with a
negative voltage (opposites attract, just like with magnets). The electronics in the smoke detector
sense the small amount of electrical current that these electrons and ions moving toward the
plates represent.
When smoke enters the ionization chamber, it disrupts this current -- the smoke particles attach
to the ions and neutralize them. The smoke detector senses the drop in current between the
plates and sets off the horn.
Fire Detection Principles
Automatic Detectors – Heat/Thermal
Heat detectors are the oldest type of automatic fire detection device. They began
development of automatic sprinklers in the 1860s and have continued to the present
with proliferation of various types of devices.
Heat detectors that only initiate an alarm and have no extinguishing function are still in use.
Although they have the lowest false alarm rate of all automatic fire detector devices, they
also are the slowest in fire detecting. A heat detector is best situated for fire detection in a
small confined space where rapidly building high-output fires are expected, in areas where
ambient conditions would not allow the use of other fire detection devices, or when speed of
detection is not a prime consideration.
Heat detectors are generally located on or near the ceiling and respond to the convected
thermal energy of a fire. They respond either when the detecting element reaches a
predetermined fixed temperature or to a specified rate of temperature change. In general,
heat detectors are designed to operate when heat causes a prescribed change in a
physical or electrical property of a material or gas.
2007 NFPA 72, 3.3.43.9 Heat Detector. A fire detector that detects either abnormally
high temperature, or rate of temperature rise, or both.
Heat detectors can be sub-divided by their operating principles:
Fire Detection Principles
Automatic Detectors – Fixed Temp.
Fixed-temperature heat detectors are designed to alarm when the temperature of the
operating elements reaches a specific point. The air temperature at the time of alarm is
usually considerably higher than the rated temperature because it takes time for the air
to raise the temperature of the operating element to its set point. This condition is called
thermal lag. Fixed-temperature heat detectors are available to cover a wide range of
operating temperatures - from about 135'F (57'C) and higher. Higher temperatures
detectors are also necessary so that detection can be provided in areas normally subject
to high ambient temperatures, or in areas zoned so that only detectors in the immediate
fire area operate.
Hochiki DFE Series Heat Detector
2007 NFPA 72, 3.3.43.7 Fixed-Temperature Detector. A device that responds when
its operating element becomes heated to a predetermined level.
Fire Detection Principles
Automatic Detectors – Rate-of-Rise
One effect that flaming fire has on the surrounding area is to rapidly increase air
temperature in the space above the fire. Fixed-temperature heat detectors will not
initiate an alarm until the air temperature near the ceiling exceeds the design operating
point. The rate-of-rise detector, however, will function when the rate of temperature
increase exceeds a predetermined value, typically around 12 to 15'F (7 to 8'C) per
minute. Rate-of-rise detectors are designed to compensate for the normal changes in
ambient temperature that are expected under non-fire conditions.
Hochiki DSC-EA Heat Detector
2007 NFPA 72, 3.3.43.18 Rate-of-Rise Detector. A device that responds when the
temperature rises at a rate exceeding a predetermined value
Fire Detection Principles
Automatic Detectors – Combination
Combination detectors contain more than one element which responds to fire. These detectors
may be designed to respond from either element, or from the combined partial or complete
response of both elements. An example of the former is a heat detector that operates on both
the rate-of-raise and fixed-temperature principles. Its advantage is that the rate-of-rise element
will respond quickly to rapidly developing fire, while the fixed-temperature element will respond
to a slowly developing fire when the detecting element reaches its set point temperature. The
most common combination detector uses a vented air chamber and a flexible diaphragm for the
rate-of-rise function, while the fixed-temperature element is usually leaf-spring restrained by a
eutectic metal. When the fixed-temperature element reaches its designated operating
temperature, the eutectic metal fuses and releases the spring, which closes the contact.
Hochiki
Photoelectric/Heat
Smoke Detector
Hochiki DCD Series
Fixed Temp/Rate of
Rise Heat Detector
2007 NFPA 72, 3.3.43.4 Combination Detector. A device that either responds to more than one
of the fire phenomena or employs more than one operating principle to sense one of these
phenomena. Typical examples are a combination of a heat detector with a smoke detector or a
combination of rate-of-rise and fixed temperature heat detector. This device has listings for each
sensing method employed.
Fire Detection Principles
Automatic Detectors – Flame
A flame detector responds either to radiant energy visible to the human eye (approx.
4000 to 7700 A) or outside the range of human vision. Similar to the human eye, flame
detectors have a 'cone of vision', or viewing angle, that defines the effective detection
capability of the detector.
With this constraint, the sensitivity increases as the angle of incidence decreases.
Such a detector is sensitive to glowing embers, coals, or flames which radiate energy
of sufficient intensity and spectral quality to actuate the alarm. Each type of fuel, when
burning, produces a flame with specific radiation characteristics. A flame detection
system must be chosen for the type of fire that is probable. For example an ultraviolet
(UV) detector will respond to a hydrogen fire, but an infrared (IR) detector operating in
the 4.4 micron sensitivity range will not. It is imperative therefore; that a qualified fire
protection engineer is involved in the design of these systems, along with assistance
from the manufacturer's design staff.
2007 NFPA 72, 3.3.43.8 Flame Detector. A radiant energy-sensing detector that
detects the radiant energy emitted by a flame.
2007 NFPA 72, 3.3.43.16 Radiant Energy-Sensing Fire Detector. A device that
detects radiant energy, such as ultraviolet, visible, or infrared, that is emitted as a
product of combustion reaction and obeys the laws of optics.
Fire Detection Principles
Automatic Detectors – Flame
Due to their fast detection capabilities, flame detectors are generally used only in highhazard areas, such as fuel-loading platforms, industrial process areas, hyperbaric
chambers, high-ceiling areas, and atmospheres in which explosions or very rapid fires
may occur. Because flame detectors must be able to 'see' the fire, they must not be
blocked by objects placed in front of them. The infrared-type detector, however, has
some capability for detecting radiation reflected from walls.
Hochiki HF-24 Flame Detector
Fire Detection Principles
Automatic Detectors – Linear Type
2007 NFPA 72, 3.3.43.10 Line-Type Detector. A device in which detection is continuous
along a path. Typical examples are rate-of-rise pneumatic tubing detectors, projected
beam smoke detectors, and heat sensitive cable.
2007 NFPA 72, 3.3.43.15 Projected Beam-Type Detector. A type of photoelectric light
obscuration smoke detector wherein the beam spans the protected area.
2007 NFPA 72, 3.3.181.3 Photoelectric Light Obscuration Detection. The principle
of using a light source and a photosensitive sensor onto which the principal portion of
the source emission is focused. When smoke particles enter the light path, some of the
light is scattered and some of the light is absorbed, thereby reducing the light reaching
the receiving sensor. The light reduction signal is processed and used to convey an
alarm condition when it meets preset criteria.
Fire Detection Principles
Automatic Detectors – Air Sampling
2007 NFPA 72, 3.3.43.1 Air Sampling-Type Detector. A detector that
consists of a piping or tubing distribution network that runs from the detector to
the area(s) to be protected. An aspiration fan in the detector draws air form the
protected area back to the detector through air sampling ports, piping, or
tubing. At the detector, the air is analyzed for fire products.
Building Notification
Notification Appliances
2007 NFPA 72, 3.3.113 Notification Appliance. A fire alarm system
component such as a bell, horn, speaker, light or text display that provides
audible, tactile, or visible outputs, or any combination thereof.
2007 NFPA 72, 3.3.113.1 Audible Notification Appliance. A notification
appliance that alerts by the sense of hearing.
2007 NFPA 72, 3.3.113.3 Visible Notification Appliance. A notification
appliance that alerts by the sense of sight.
Fire Alarm Circuit Classes
2007 NFPA 72, 6.4.2.1 Class. Initiating device circuits, notification appliance
circuits, and signaling line circuits shall be permitted to be designated as either
Class A or Class B, depending on their performance during nonsimultaneous
single circuit fault conditions as specified by the following:
(1) Initiating device circuits and signaling line circuits that transmit an alarm or
supervisory signal, or notification appliance circuits that allow all connected
devices to operate during a single open or a nonsimultaneous single ground
fault on any circuit conductor, shall be designated as Class A
(2) Initiating device circuits and signaling line circuits that do not transmit an
alarm or supervisory signal, or notification appliance circuits that do not allow
all connected devices to operate beyond the location of a single open on any
circuit conductor, shall be designated as Class B
2007 NFPA 72, 6.4.2.2. An open or ground fault condition shall result in the
annunciation of a trouble signal at the protected premise within 200 seconds as
required in 4.4.7
Class B Circuits
Class B Initiating Device Circuit
4.7K
EOLR
Class B Notification Appliance Circuit
4.7K
EOLR
End of line supervision resistors
are required to supervise the
integrity of the loop.
Class B Circuits
Class B Initiating Device Circuit
4.7K
EOLR
4.7K
EOLR
Class B Notification Appliance Circuit
Single open circuit condition causes a
trouble on the panel and renders all
devices beyond the fault inoperative.
Class A Circuits
Class A Initiating Device Circuit
Class A Notification Appliance Circuit
End of line supervision resistors are not
necessary as the loop returns to the
panel and is driven from both ends.
Class A Circuits
Class A Initiating Device Circuit
Class A Notification Appliance Circuit
Single open circuit condition causes a
trouble on the panel. All devices on the
loop remain operative.
Additional Fire Alarm Terminology
Addressable Device - A fire alarm system component with discreet identification that can
have its status individually identified or that is used to individually control other functions.
Analog Addressable Sensor - An initiating device that transmits a signal indicating varying
degrees of condition as contrasted with a conventional or addressable initiating device, which
can only indicate an off/on condition.
Signaling Line Circuit (SLC) - A circuit or path between any combination of circuit interfaces,
control units, or transmitters over which multiple system input signals or out put signals or
both are carried.
SLC Interface - A system component that connects a signaling line circuit to any
combination of initiating devices, initiating device circuits, notification appliances,
notification appliance circuits, system control outputs and other signaling line
circuits.
Protocol - A language for communicating between control panels and their proprietary devices.
Comparing System Types
To better understand today’s newer technology, a firm understanding of the types of systems
available is necessary. The three most popular types of systems installed today are:
•Conventional
•Addressable
•Analog Addressable
Conventional Systems



Conventional control panels range in size from 1 zone
to over 100 zones.
Zones typically consist of some or all of the initiating
devices in an area or floor of a building.
Some control panels zone capacity is expandable
while others are not, limiting its usefulness if a facility
adds additional buildings or rooms.
Conventional Systems
Zone 1
4.7K
EOLR
Zone 2
FIRE
FIRE
FIRE
FIRE
FIRE
FIRE
FIRE
FIRE
FIRE
FIRE
FACP
SILENT KNIGHT
NAC 1
SILENT KNIGHT
SILENT KNIGHT
SILENT KNIGHT
SILENT KNIGHT
4.7K
EOLR
Multiple devices are combined
into a single zone. Zones can
contain 30 or more devices.
Conventional Systems
Zone 1
4.7K
EOLR
Zone 2
FIRE
FIRE
SILENT KNIGHT
NAC 1
4.7K
EOLR
Care must be taken when laying
out zones to comply with code
requirements.
Zone Considerations

2007 NFPA 72 6.8.5.5.2 Limits the number of waterflow
switches in a single zone to 5.

2007 NFPA 72 6.8.5.6.2 Limits the number of
supervisory devices in a single zone to 20.

2007 NFPA 72 Annex A.4.4.6.6 Suggests that the
maximum number of square feet in a single zone be
limited to no more than 22,500.
Conventional Systems
Zone #1
4.7K
EOLR
Zone #2
NAC #1
4.7K
EOLR
Wiring must be installed in a
supervised manner either Class A,
or Class B with an EOLR.
Conventional Systems
Zone #1
4.7K
EOLR
Zone #2
FIRE!
NAC #1
4.7K
EOLR
Alarm conditions are annunciated
by zone only. Inspection is
required to determine the device.
Conventional Systems
Zone #1
4.7K
EOLR
Zone #2
NAC #1
4.7K
4.7K
EOLR
EOLR
Trouble conditions are annunciated
by zone only. Inspection is required
to determine the cause.
Conventional Systems
Zone #1
4.7K
EOLR
Zone #2
RJ
RJ
NAC #1
4.7K
EOLR
Information transmitted to the central
station is by zone at best. Many
panels send Alarm, Supv, Trbl only.
Addressable Systems

FACP


An addressable systems point capacity is
determined by the amount of SLC “Signaling
Line Circuits” it contains.
Each SLC circuit provides power,
communication, & supervision for all of the
devices connected to it.
Each SLC can accommodate over 100
addressable devices, depending upon the
manufacturer.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
Addressable
Smoke Detector
FIRE
SILENT KNIGHT
FACP
Addressable
Relay Module
(Fan Shutdown)
NAC #1
4.7K
EOLR
Each SLC loop can contain a variety of
addressable devices. Non-addressable devices
are connected via addressable module.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Each point on the SLC loop is given
a unique address when installed.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
< Replay
Supervision is accomplished from
the panel by polling the devices on
the SLC loop.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
FIRE!
NAC #1
4.7K
EOLR
ALARM
POINT 006
LOBBY SMOKE DETECTOR
Alarm conditions are annunciated
by point allowing responding
personnel to quickly find the fire.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
TRBL POINT 006
DISCONNECTED
LOBBY SMOKE DETECTOR
Trouble conditions can be located
more quickly by analyzing the
affected points.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
RJ
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
RJ
NAC #1
4.7K
EOLR
More detailed information can be
sent to the central station aiding in
a quick resolution to the problem.
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
NAC #1
4.7K
EOLR
Since supervision is accomplished
through polling, t-tapped wiring is
permitted. (Class B wiring)
Addressable Systems
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
FACP
Addressable
Relay Module
(Fan Shutdown)
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
003
FIRE!
NAC #1
4.7K
EOLR
Many systems support flexible
input/output programming to link
initiating devices to outputs.
Comparison

Conventional




Lower initial
equipment costs.
Wide range of
compatible devices.
Can be easier to
program.
Limited expansion
capability.

Addressable




Easier to install.
More system status
information at the
panel and central
station.
Input/Output
programming much
more flexible.
Usually much more
room available to
expand.
Analog Addressable Systems


Detectors in an analog addressable systems
become “sensors” relaying information to the
control panel corresponding to how much
smoke or heat that detector is sensing.
The control panel makes the decisions based
on this information when to alarm etc.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
HEAT DETECTOR
MECHANICAL ROOM
POINT 001
A=062
NORMAL
F=190
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Detector
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
SMOKE DETECTOR
LOBBY NORTH
POINT 002
A=060
NORMAL
F=188
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
RELAY MODULE
FAN SHUTDOWN
POINT 003
A=N/A
NORMAL
F=N/A
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
INPUT MODULE
WATERFLOW
POINT 004
A=N/A
NORMAL
F=N/A
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
INPUT MODULE
MANUAL PULL
POINT 005
A=N/A
NORMAL
F=N/A
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
SMOKE DETECTOR
FRONT DESK
POINT 006
A=061
NORMAL
F=189
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
HEAT DETECTOR
MECHANICAL ROOM
POINT 001
A=062
NORMAL
F=190
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
SMOKE DETECTOR
LOBBY NORTH
POINT 002
A=060
NORMAL
F=188
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
RELAY MODULE
FAN SHUTDOWN
POINT 003
A=N/A
NORMAL
F=N/A
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
INPUT MODULE
WATERFLOW
POINT 004
A=N/A
NORMAL
F=N/A
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
INPUT MODULE
MANUAL PULL
POINT 005
A=N/A
NORMAL
F=N/A
10K
EOLR
Supervision is still checked by
polling. In addition an analog
value is transmitted to the
panel for processing.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
SMOKE DETECTOR
FRONT DESK
POINT 006
A=061
NORMAL
F=189
10K
EOLR
< Replay
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
HEAT DETECTOR
MECHANICAL ROOM
POINT 001
A=062
NORMAL
F=190
10K
EOLR
This analog value corresponds
to the amount of heat or
smoke in that detectors area
of coverage. Higher = more.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
HEAT DETECTOR
MECHANICAL ROOM
POINT 001
A=062
NORMAL
F=190
10K
EOLR
If the analog value exceeds
the alarm threshold, an alarm
occurs. This alarm threshold is
calculated by the panel.
Analog Addressable Systems
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
Addressable
Relay Module 003
(Fan Shutdown)
NAC #1
INPUT MODULE
WATERFLOW
POINT 004
A=N/A
NORMAL
F=N/A
10K
EOLR
Input/output modules do not
relay analog values to the
panel as they are monitoring
or controlling on/off devices.
Analog Addressable
Features

An analog addressable control panel is capable of
several enhanced features not available on conventional,
and some addressable systems.
 Drift Compensation / Maintenance Alert
 Adjustable Detector Sensitivity
 Day/Night Detector Sensitivity Adjustment
 U.L. Calibrated Sensitivity Test Instrument
Drift Compensation


Drift compensation is the process by which an analog
addressable control panel automatically adjusts an
analog detectors alarm threshold to compensate for
contaminants such as dust.
This ensures the detector maintains a consistent
sensitivity level, helping to avoid false alarms due to
dirty detectors.
Maintenance Alert


Drift compensation occurs until it is nearing a point
where it can no longer compensate and remain within
U.L. requirements. This point is called “Maintenance
Alert”
Some systems handle a maintenance alert condition as
a trouble while others flag the condition only, and
continue to operate normally.
Calibration Trouble


A detector in a maintenance alert condition will
eventually go into calibration trouble if not serviced.
A detector in calibration trouble is not functioning
correctly and requires service immediately.
Adjustable (Day/Night)
Sensitivity

In order to allow for varying environmental conditions or
to provide quicker detection, analog systems typically
allow you to change the sensitivity of a detector within a
range of U.L. tolerances.

This is typically made user friendly by giving the installer
choices such as high-medium-low.
Adjustable (Day/Night)
Sensitivity

By changing a detectors sensitivity you are instructing
the panel to adjust its alarm threshold (analog) value up
or down accordingly.

Some systems allow this sensitivity adjustment to
happen automatically on a day/night schedule.
U.L. Calibrated Sensitivity Test


1996 NFPA 72 7-3.2.1
Detector sensitivity shall be tested within 1 year after installation and
every alternate year thereafter. After the second required calibration
test, where sensitivity tests indicate that the detector has remained
within its listed and marked sensitivity range, the length of time shall be
permitted to be extended to a maximum of 5 years. …
Testing Methods





A calibrated test method; or
Manufacturers calibrated sensitivity test instrument; or
Listed control equipment arranged for the purpose; or
Smoke detector/control unit arrangement whereby the
detector causes a signal at the control unit where its
sensitivity is outside the acceptable range; or
Other approved calibrated method acceptable to AHJ
U.L. Calibrated Sensitivity Test

Analog addressable control panels are UL listed for the
purpose of performing the calibrated sensitivity testing
internally.

A printout from the panel is usually available to provide
evidence to the AHJ that the test was performed.
How Analog Works
Detectors range of analog values
255
240
210
Range (.5% - 4% per foot obscuration)
that U.L. requires, to be listed as a
smoke detector.
180
150
120
90
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
Detectors range of analog values
255
240
210
On the other side of the graph, the range
of analog values for the detector is
plotted. In this case the range is 0-255.
180
150
120
90
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
Detectors range of analog values
During powerup the detector
performs a self
test simulating
4% per foot
obscuration.
This value is
plotted, in this
case 193.
255
240
210
193
180
150
120
90
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
Detectors range of analog values
The system
them initializes
and records the
0% per foot
obscuration
(normal no
smoke) value
for that
detector. In this
case 60.
255
240
210
193
180
150
120
90
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
Detectors range of analog values
A line is drawn
connecting
these two
points. This line
is referred to as
the detectors
calibration
curve.
255
240
210
193
180
150
120
90
Calibration Curve
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
Once the
calibration curve
is established
the panel can
calculate an
alarm threshold
value for any
valid sensitivity
setting.
Detectors range of analog values
255
240
210
193
180
150
145
120
112
90
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
The panel also
calculates the
initial ranges for
the drift
compensation &
maintenance
alert functions.
Detectors range of analog values
255
240
210
193
180
Alarm
150
145
120
Calibration Trouble
Maintenance
90
Normal
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
As the detector
gets dirty the
clear air value
will increase.
Detectors range of analog values
255
240
210
193
180
Drift
compensation
adjusts the
alarm threshold
value
accordingly.
Alarm
150
145
120
Calibration Trouble
Maintenance
90
Normal
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
As the detector
gets dirty the
clear air value
will increase.
Detectors range of analog values
255
240
210
193
180
Drift
compensation
adjusts the
alarm threshold
value
accordingly.
Alarm
150
145
120
Calibration Trouble
Maintenance
90
Normal
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
As the detector
gets dirty the
clear air value
will increase.
Detectors range of analog values
255
240
210
193
180
Drift
compensation
adjusts the
alarm threshold
value
accordingly.
Alarm
150
120
Calibration Trouble
Maintenance
90
Normal
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
As the detector
gets dirty the
clear air value
will increase.
Detectors range of analog values
255
240
210
193
180
Drift
compensation
adjusts the
alarm threshold
value
accordingly.
Alarm
155
150
120
Calibration Trouble
Maintenance
90
Normal
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
As the detector
gets dirty the
clear air value
will increase.
Detectors range of analog values
255
240
210
193
180
Drift
compensation
adjusts the
alarm threshold
value
accordingly.
Alarm
160
150
120
Calibration Trouble
Maintenance
90
Normal
60
30
.5%
1%
2%
3%
4% per foot obscuration
How Analog Works
Even though the
detector has
gotten dirty, it
has still
maintained a
2.5% sensitivity
level.
Detectors range of analog values
255
240
210
193
180
Alarm
165
150
120
Calibration Trouble
Calibration Trouble
Maintenance
90
Normal
60
< Replay
30
.5%
1%
2%
3%
4% per foot obscuration
Communication Protocols

Each manufacturer of (analog) addressable fire alarm systems
utilize a unique communications protocol on the SLC loop to
communicate between the control panel and the addressable
devices.

Most protocols are developed by detector manufacturers.

Many manufacturers subtly modify standard protocols, developed by
detector manufacturers, to provide a proprietary environment for
their equipment & distributors.
Communication Protocols

Many of the panels installation requirements and
operational parameters are based on the communication
protocol used.
 SLC Loop Length
 SLC Loop Wire Type
 SLC Loop Communications Speed
 SLC Loop Alarm Response Time

Communication protocols can be broken down into two
categories.
 Non-Digital
 Digital
Comparing Protocols
Addressable
Heat Detector
Addressable
Smoke Detector
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Detector
006
005
003
Addressable
Relay Module
(Fan Shutdown)
To take a closer look at
communication protocols we
can look at non-digital and
digital SLC Loops through an
oscilloscope.
Non-Digital Protocol
Each detector when
polled responds to the
panel with square wave
pulses.
Non-Digital Protocol
The panel reads these
square wave pulses and
determines the values by
measuring the length
(time) of each.
Non-Digital Protocol
?
Various sources of
interference can cause
these square wave pulses
to round off. This makes
an accurate reading very
difficult.
Non-Digital Protocol
?
Most manufacturers that
utilize a non-digital
protocol will specify
special requirements
such as twisted or
shielded wire to
counteract this problem.
Digital Protocol
1 1 1 1
24v
0
0 0
Using a digital protocol
the panel looks for for a
series of “1” or “on” bits
that are detected by
looking for voltage rather
than the length of a pulse.
Digital Protocol
1 1 1 1
24v
0
0 0
Even if a source of
interference causes
rounding off of the digital
pulses the voltage is still
present for the panel to
determine the digital
value.
Digital Protocol
1 1 1 1
24v
0
Digital protocol panels do
not typically require
special cabling since
interference does not
pose any substantial
signal problems.
0 0
Retrofits can be done
using existing cable.
Non-digital Loop Response

When an alarm occurs on many non-digital protocol
systems, some panels must continue polling until it
reaches the alarming device, before an alarm is initiated.
 Larger systems with hundreds of points can cause
delays initiating an alarm.
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
FIRE
004
SILENT KNIGHT
005
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
Addressable
Smoke Detector
006
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
A fire erupts at the Heat
Detector (Point 001) while the
system is polling the Smoke
Detector (Point 002).
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
An alarm is not initiated. The
system continues polling until
it reaches the point in alarm.
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
An alarm is not initiated. The
system continues polling until
it reaches the point in alarm.
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
An alarm is not initiated. The
system continues polling until
it reaches the point in alarm.
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
An alarm is not initiated. The
system continues polling until
it reaches the point in alarm.
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ALARM
POINT 001
HEAT DETECTOR
15-Jan-00 3:10 PM
ALARM!
Non-Digital Loop Response
Addressable
Heat Detector
Addressable
Smoke Detector
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
FIRE
001
002
Addressable
Smoke Detector
FIRE
004
SILENT KNIGHT
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ALARM
POINT 001
HEAT DETECTOR
15-Jan-00 3:10 PM
Systems with hundreds of
points can take 15 -20
seconds or longer to respond
to alarm conditions.
Digital Loop Response

When an alarm occurs on most digital protocol systems,
an interrupt request from the device sensing the alarm
interrupts the polling sequence to immediately handle
the alarm.
 Systems with hundreds of points will respond to
alarms in the same amount of time that they would to
smaller systems with very few points.
Digital Loop Response
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
006
005
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
Addressable
Smoke Sensor
Digital Loop Response
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
A fire erupts at the Heat
sensor (Point 001) while the
system is polling the Smoke
Detector (Point 002).
Digital Loop Response
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ABC FIRE SYSTEMS
ALL SYSTEMS NORMAL
15-Jan-00 3:10 PM
The Heat Sensor (Point 001)
interrupts the polling process
to handle the alarm
immediately.
Digital Loop Response
Addressable
Heat Sensor
Addressable
Smoke Sensor
001
002
Addressable
Input Module
(Waterflow)
Addressable
Pull Station
004
Addressable
Smoke Sensor
006
005
FIRE!
003
Addressable
Relay Module
(Fan Shutdown)
ALARM
POINT 001
HEAT SENSOR
15-Jan-00 3:10 PM
ALARM!
THE END
Hochiki America Corporation
7051 Village Drive, Suite 100
Buena Park, California 90621
www.hochiki.com