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Intro to Conventional Fire Alarm Systems

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Introduction to

Conventional Fire Alarm Systems


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Course Descriptionu This two-hour introductory course is for individuals with little or no experience in the fire alarm industry. The course covers the basic building blocks of modern conventional and addressable fire alarm systems. u It covers the primary and secondary functions of a fire alarm control panel, various initiating and notification devices, digital communicators, waterflow alarm and sprinkler monitoring.


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Course Contents

u Basic Elements of a Fire Alarm Systemu Supplementary Functions u Physical Elements of Fireu Initiating Devices u Notification Appliancesu Water Flow and Sprinkler Monitoringu Types of Control Panelsu Design Issuesu Notification Appliance Circuit (NACs)u Supplementary Circuit Wiring


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Life Safety!

What is the purpose of a Fire Alarm System?

Detect, Alert and Evacuate.


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Basic Fire

Let’s examine the components that make a basic Fire Alarm Control System.


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Main Controller

u The brains of the system.

u Provides power to the system, monitors inputs and controls outputs through various circuits.

u Performs other functions as required by the appropriate code.


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Elements of a Control Panel

Main Controller, Power, Inputs and Outputs


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Primary (AC)

Secondary (DC)

Requires two Power Sources

Elements of a Control Panel


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Smoke Detector

Manual Pull Station

A fire alarm system can have a variety of input devices.

Elements of a Control PanelInputs


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Inputs

u Initiating Device A system component that originates transmission of a change of state condition, such as a smoke detector, manual fire alarm box, supervisory switch, etc....

u Initiating Device Circuit (IDC) A circuit to which automatic or manual initiating devices are connected where the signal received does not identify the individual device operated.


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Horns

Strobes

Elements of a Control PanelOutputs


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Outputs

u Notification Appliance A fire alarm system component such as a bell, horn, speaker, light, or text display that provides audible, tactile, or visible output, or any combination thereof.

u Notification Appliance Circuit A circuit or path directly connected to a notification appliance.


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The Basic System

Secondary (DC)

Primary (AC)

Outputs

Inputs

Main Controller


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Supplementary Operations

u Elevator Captureu Equipment Shutdownu Air Handling Shutdownu Damper Controlu Extinguishing System

Interfaceu Event Printing u Display Monitor Interfaceu Door Holding Devices


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Supplementary Operations

u Remote Signal Annunciation - Provides critical system status and basic control capability from a more convenient location than where the control panel might be located.


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Remote AnnunciatorsRZA-5X

Remote Zone Annunciator

LCD-80F Liquid Crystal Display

Graphic Annunciator

(Custom)


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DACTsUDACT Universal Digital Communicator Transmitter

Dedicated DACT"daughterboard"

411UD Slave/Stand Alone DACT

Integral Onboard DACT


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Basic Fire Alarm TechnologySignal Initiation & Initiating Devices

What is the

threat?


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Automatic Fire Detectors

How do we detect the threat?


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u Spot Detectors provide detection concentration in a particular location - Heat & Smoke Detectors.

u Line Detectors provide continuous detection along a path - Thermal Cable & Beam Detectors.

u Air Sampling Systems draw air through pipes to an enclosed chamber for testing. - (VESDA & Duct Detectors.


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u Photoelectricu Light-Scattering (Reflective)u Light-Obscuring (Beam)

u Ionizationu Thermal (heat)u Duct



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Photoelectric Smoke DetectorsLight-Scattering Type

u These detectors use a Light-Emitting Diode (LED) that sends a beam of light into a dark chamber. A photo diode sits on the other side of a partition within the chamber. u Smoke particles entering the chamber deflect some of the light rays into the photocell. The photo cell generates a current when exposed to light, and if the current reaches a certain level, the smoke detector alarms.


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Light Scattering PrincipalSensing Chamber

LightEmitting

Diode

Photo Diode

Partition


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Light Scattering Principal


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u In a projected Beam Detector, alarms are generated by diffusing the projected light beam by a specified percentage of obscuration. Total beam blockage generally results in a trouble signal.

Photoelectric Smoke DetectorsLight Obscuration Type

u Wire the receiver unit as a 4-wire detector (separate power and sensing connections to the control panel).


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Projected Beam Principal

TransmitterReceiver

Smoke from the fire in the protected area diffuses the intensity of the beam at the receiver


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Ionization Smoke Detectorsu These detectors contain a small amount of radioactive material encapsulated in a metal chamber. Ionizing radiation develops a low, but steady electrical current. Smoke particles entering the chamber disrupt the current and trigger the detector's alarm.

u Ion detectors react more quickly to fast flaming fires that give off little smoke.

u Spot-type Detectors.


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Duct Detectors

u Photoelectric detector mounted in housing outside the ductwork that has probes that extend into the duct to sample the air inside the duct.

u Primarily used as a smoke control device to control the flow of air in ductwork.


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The i3 series is based on three guiding principles: Installation ease, Intelligence, and Instant inspection.

uPlug-In Head/Base combination.uSmoothing algorithmsuDrift compensation (automatically adjusts for dust accumulation, reducing nuisance alarms)

uOptional Sensitivity Reader

The i3 Series

This line of photoelectric smoke detectors by System Sensor consists of 2- and 4-wire detectors, offered with or without a fixed 135° temperature thermal sensor.


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Manual Initiating DevicesThe Manual Fire Alarm Pull Station


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Initiating DevicesManual Fire Alarm Stations

u Manually operated device used to initiate an alarm signal.u Single Action Stations require a single

operation to activate it. Generally a pulling down action.

u Dual Action Stations require two distinct operations. A set-up and an activating action.

u Breakglass Stations have an inhibit device that must be damaged to activate the station (non-ADA compliant).


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Initiating DevicesManual Fire Alarm Stations

u Optional Featuresu With and without key locks or hex key locksu Weatherproof models with special backboxesu With auxiliary contactsu Multiple languages, even dual languages.u With a pre-signal featureu With screw-terminal or pigtail connectionsu Conventional and Addressableu Metal or Polycarbonate


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Single-Action Manual Station

Spring-loadedreleasing

switch

ResetKey

ActuationHandle


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Dual-Action Manual Station

InitialPre-Actuator

Actuator


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Non Alarm Pull Stations


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Heat DetectorsHeat detectors are the oldest type of automatic fire detection device. Not considered direct Life Safety devices, these detectors do contribute to the detection of a fire.


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Heat Detectorsu Fixed Detectors alarm when the sensing element reaches a certain set point. Two common ones have 135 and 200-degrees F range. The Fixed element is generally a non-restorable type, and when activated, must be replaced.u Rate-of-Rise Detectors respond when the rate of temperature increase is greater than an allowable limit (15 degrees in 60 secs.) (placement in a stable environment) (e.g.. ovens, heating vents, etc.). The Rate-of-Rise element is restorable when conditions return to normal.u Rate Compensation will respond regardless of the rate of temperature rise.


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Heat DetectorsRate Compensation Type

u Detector responds when the temperature of the surrounding air reaches a predetermined level, regardless of the rate of temperature rise.u The system compensates for Thermal Lag.u During a slow rate of temperature rise there is more time for heat to penetrate the inner element, which inhibits contact closure until the total device reaches the rated temperature level.u During fast rate of increase, there is less time for heat to penetrate the inner element, which exerts less inhibiting effect, so contact closure is still obtained at the rated temperature.


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Heat Detectors

u DON’T Paint Heat Detectors!!!

u Why? Because “Thermal Lag” occurs when the physical properties of the Heat detector cause it to lag behind the alarm condition of the surrounding air.


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Heat Detectorsu Exhibit the lowest false alarm rate of all

automatic fire detector devices, u Slowest-responding fire detection devices. u Best used in applications where

u Fast-developing, large fires are expected.u Environment won't allow the use of other

fire detection devices.u The speed of detection is not a prime

consideration.


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Heat DetectorsHeat Sensitive Cable

u A line-type initiating device whose sensing element comprises, in one type, two current-carrying wires held separated by heat-sensitive insulation which softens at the rated temperature, thus allowing the wires to make electrical contact.

u Installed at the exact point of risk to provide rapid localized detection of abnormal temperature rises(overloaded or short-circuited high voltage power wiring).


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Heat Detector Heat Sensitive Cable

Actuators

Outer Insulation

Protective Tape

Heat SensitiveMaterial


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Notification Appliances Types

u Audible - Horns, Bells, Sounders, Sirens, Chimes, Speakers.

u Visual - Strobes

u Physical - Bed shakers

u Olfactory - Smell


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Audible Devices

u Bells: Only used if they are only for fire, or have a distinctive sound from other bell signaling devices. Often used as an external gong to indicate the flow of water in the sprinkler system.

u Horns: Loud and distinctive output. Often used in high-noise environments, such as manufacturing plants.


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Audible Devices

u Sounders: Electronic or mechanical audible devices, which are capable of producing a variety of tones. Often, the tone is selectable during installation of the device.

u Chimes: Soft-toned appliances used where loud noises could be disruptive to other operations. Generally used where qualified personnel are continuously in attendance.


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Audible Devices

u Sirens: Extremely loud devices generally limited in use to outdoor or heavy industrial areas.

u Speakers: Audible devices used in conjunction with voice evacuation messages. Life-Safety speakers are not generally associated with Muzak systems.


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Audible Codes

u Coded outputs are required in many applications. This can be accomplished by pulsing tones for different areas of the building, or zoning the outputs (floor above - floor below).

u General alarm codes commonly used are March Time (110-120 ppm) or Temporal code (ANSI Evacuation Code 3).


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Visual Signaling

Appliances

Visual signaling appliances are used in high-noise environments, in areas occupied by hearing-impaired individuals, or in areas where audible devices may not be desired.


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Visual Devices

Speaker/Strobe

Chime/Strobe

Horn/Strobe

Strobe


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Selectable-Output Visual Devices

u Selectable Candela Output (15 - 30 - 60 -75 - 110)

u Selectable Operating Voltage (12 or 24 volts)

u Offered in Strobe and Horn/Strobe combinations


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Types of Power

u For powering the various devices connected to a fire alarm system, control panels supply auxiliary power. There are two main types of power that you MUST be aware of:

u Full-Wave Rectified (Special Purpose) Power - Unregulated output directly. High ripple voltage. Do not use for SmokeDetectors! Only use NAC devices listed for use with this type of power.

u Filtered Regulated Power - Most stable output. Minimal ripple voltage. Used for Smoke Detectors, and some remote supplementary devices.


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Full-Wave Rectified Power

24v

0v

42v


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Filtered Regulated Power

24v

0v


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Secondary Power

u Direct Current - Clean, absolute filtered poweru Supplies the system with operating power under

the loss of primary (AC) for at least 24 hours of standby (quiescence) followed by 5 minutes in alarm. Voice systems require 15 minutes in alarm.

u Rated in AMP-HOURS (AH).u Must be calculated!


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Relays and Contacts

u Form A - refers to a relay with contacts for common and normally open ONLY.

u Form B - refers to a relay with contacts for common and normally close ONLY.

u Form C - refers to a relay with contacts for common, normally open, and normally closed.

u Dry Contacts -By magnetically controlling the state of the contacts, the control panel is electrically isolated (and thus protected) from power connected to the contacts..


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Relays and Contacts

When a relay is not active, the contacts are in their normal position.

Normally Closed

Normally OpenCommon


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Relays and Contacts

When the relay is activated, current passing through the relay coil magnetically influences the common "wiper", moving it to the opposite position.

Normally Closed

Normally OpenCommon


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Relays and Contacts

"Fail-Safe" relays are energized during "normal" conditions. The relay is activated by deenergizingthe coil, guaranteeing activation of the desired signal during loss of all power to the system.

Normally Closed

Normally Open

Common


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Initiating Devices

Sprinkler Systems

Monitoring


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u Wet-Pipe Sprinkler Systems use a vane-activated Water Flow Device (WFD) sized to the piping. The device reacts to a change in flow pressure of 10 psi, which is the equivalent of one sprinkler head activating. Retard devices inhibit false activation due to changes in water supply pressure.

Fire Sprinkler Systems


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Waterflow Detectors

Pressure Gauges

Tamper Switches


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u Dry-Pipe Sprinkler: An automatic sprinkler system where all piping contains air under pressure. When a sprinkler head opens, the air is released and water flows into the system and through any open sprinkler heads into the fire. This type of system is used when freezing of water in the pipes is a concern.

Fire Sprinkler Systems

u Dry-Pipe Sprinkler Systems use a pressure switch. The device reacts to a change in pressure due to water filling the system.


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Sprinkler Monitoring

u Sprinkler Systems have water feed control valves. These control valves shut off the water supply to the sprinkler system and render it useless. A monitoring device should be attached to every critical control valve in the system, whether it's a gate valve, indicator valve, or butterfly valve. Whenever the valve is shut off, a supervisory alarm signal (as opposed to a Fire or Waterflow alarm) is generated.

u The two most common types of Supervisory Tamper Switches are OSY and PIV.


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Sprinkler Monitoring

OS&Y


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Sprinkler MonitoringPIV


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The Systems


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u Conventional (hard wired)u Fixed u Programmable

u Addressable (multiplexed)

u Intelligent (analog data transfer)

Types of Fire Alarm Control Panels


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u Simplest type of control unit.u Generally, a single circuit board contains power

supply, control, initiating and notification circuitry.u Some models use auxiliary circuit boards to perform

special functions.u Input/output devices connect to dedicated circuits.u Designated outputs occur when initiating signals are

received.u Limited special functions and capabilities.

Examples: Fire-Lite MS-2 and MS-4

Conventional “Hard Wired” System


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Addressable System

u Each device (detector, pull station…) has a unique number assigned to it called the address for reporting alarms and troubles.

u Employs a Signaling Line Circuit (SLC) Loop along which all addressable input and output devices are connected to the fire alarm control panel.

u Addressable devices transmit an electronic message back to the Control Unit representing their state (Normal, Alarm, Trouble) when polled by the Control Unit.


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Addressable Modules

These systems can also monitor conventional initiating devices using addressable monitor modules.

SLC Loop

24 VDC Power


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Addressable Pull Stations

Addressable Module


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Typical SLC


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Input-to-Output Mapping


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Software Zoning

u Floor-Above/Floor Belowu Elevator Recallu Smoke Controlu Ring-By-Zoneu Door Locks (Card Access)u Cross Zoning


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Intelligent System

u Always an Addressable System.u Processes detailed, analog data from

detectors about smoke levels.u Can provide sensitivity data for each

detector.u Employs Drift Compensation (self calibration)

in it's detectors.

Examples: Fire-Lite MS-9200, MS-9200UD & MS-9600.


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Design and Application


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Design Issuesu Device Selection

u Photo vs. Ion, line versus spot.u What is are the total costs of one type versus another?u How does the environment affect device selection?u Does the device meet code specifications and code?

u Placement of Devices (where do you place smoke detectors, pull stations, notification appliances)?

u Calculations (how do you calculate battery size and NAC voltage drops?).

u Programming (how will you accomplish your non-general alarm events?).


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Spot Detector Placement

u Total (complete) Coverage includes all rooms, halls, storage areas, basements attics, lofts, spaces above suspended ceilings, and other subdivisions and accessible spaces as well as the inside of all closets, elevator shafts, enclosed stairways, dumbwaiter shafts and chutes.

NFPA 72 2002 Section 5.5.2.1

Exception - inaccessible areas that DO NOT contain combustible materials do not require smoke detection


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u Partial Coverage calls for smoke detection in all common areas and work spaces, such as corridors, lobbies, storage rooms, equipment rooms, and other tenantless spaces.

The building owner must understand that a fire alarm system may not detect a fire that develops within any area without smoke detection until that fire has reached proportions that may seriously compromise the safe evacuation of occupants and the timely notification of fire responders.

CAUTION!


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Smoke Detector

30’

21’

Typical areaof room protection

Maximumradius of protection

Spot detector placement is based on central mounting of a detector in a 30’ X 30’ room. No area may be more than 21’ from the detector.

21’

30’


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Smoke Detector

10’

21’

Room Maximumradius of protection

Note that in this application, two detectors are not required because all areas within the room are within 21 feet of the detector.

41’


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15’ 15’

15’ 15’

30’

30’


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Heat Detector SpacingCeiling Height

(feet)Percent (%) of Listed Spacing

0 -10 10-1212-1414-1616-1818-2020-2222-2424-2626-2828-30

10091847771645852464034


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Initiating DevicesManual Fire Alarm Pull Stations


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Manual Fire Alarm StationsMounting Locations

u Manual fire alarm stations shall be located within 5 feet of the exit doorway opening of each floor.

u Grouped openings over 40 feet in width require pull stations on either side of the opening.

u Additional pull station will be installed no more than 200 linear feet apart.

u Each manual fire alarm station shall be conspicuous, unobstructed, and accessible, and of a contrasting color to the background on which they are mounted.


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Manual Fire Alarm Stations

u NFPA 72 - Mount pull station so that operable part is 42" to 54" from the floor.

u ADA Accessibility Guidelines u Forward reach: If access is only from a

forward approach, mount 15-48”. u Side reach: If clear space allows a parallel

approach, mount 9-54”. If side reach is over an obstruction, use forward reach rules.


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Manual Fire Alarm Stations

The height is measured from the floor to the point of actuation.

48 Inches


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Designing with Notification Appliances


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ADA vs NFPAu Conflicts exist between ADA and NFPA guidelines regarding requirements for notification appliances in fire alarm systems.

u If the specifications call for ADAcompliance, it is a federal law which must be obeyed.

u It is believed that newly-revised ADA Accessibility Guidelines will reference NFPA 72 2002.


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Ambient Noise

u Ambient Noise Level – the level of noise around us, or encircling us. Often referred to as “background noise”.

u Decibels (dB)– Sound pressure is rated in decibels, which is a unit for measuring relative loudness.

u dBA - A dB scale referenced to the minimum pressure that can be detected by the human ear.


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Ambient Noise

u 1 dBA (faintest audible sound) –Remember the hearing test?

u 50 dBA Typical conversation

u 80 dBA Alarm Clock

u 130 dBA (painful – ear damage possible).


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Typical Ambient Noise Levels Business Occupancies 55 dBA Educational Occupancies 45 dBA Industrial Occupancies 80 dBA Institutional Occupancies 50 dBA Mercantile Occupancies 40 dBA Piers and Water-Surrounded Structures 40 dBA Places of Assembly 55 dBA Residential Occupancies 35 dBA Storage Occupancies 30 dBA Thoroughfares, High Density Urban 70 dBA Thoroughfares, Medium Density Urban 55 dBA Thoroughfares, Rural and Suburban 40 dBA Tower Occupancies 35 dBA Underground Structures and Windowless Buildings

40 dBA

Vehicles and Vessels 50 dBA


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Operating Modes

u Public Mode – Audible or visible signaling to occupants or inhabitants of the area protected by the fire alarm system.

u Private Mode – Audible or visible signaling only to those persons directly concerned with the implementation and direction of emergencyaction initiation and procedure in the area protected by the fire alarm system.


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Audible Devices - Public Mode

u NFPA: 15 dB above average ambient sound level or 5 dB above maximum 60-second sound level, whichever is greater (minimum of 75 dBA to a maximum of 120 dBA).

u ADA: If provided, 15 dB above average ambient sound level or 5 dB above maximum 60-second sound level, whichever is greater (maximum of 120 dBA).


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Audible Devices - Private Mode

u NFPA: Minimum of 45 dBA, maximum of 120 dBA, at least 10 dB above average ambient sound level or 5 dB above maximum 60-second sound level, whichever is greater.


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Visual Signaling Appliance

u Above 105 dbA: When the average ambient sound level is greater than 105 dbA, visual signaling appliances are required.u Indoor concertsu Drop forge shopsu Printing presses


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Visual SignalingADA Requirements

u Americans with Disabilities Act sets provisions for visual appliances:u Intensity minimum of 75 cd in non-sleeping areas,

and 110 cd in sleeping areas.u Lamp shall be a Xenon strobe type or equivalent.u The color shall be clear or nominal white.u Pulse duration 0.2 sec. with a 40% duty cycle.u Flash Rate 1 - 3 per second (1-3 Hz).


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Wall-Mounted Appliances

NFPAu Wall mounted devices shall have their bottoms at heights above the finished floor of not less than 80 inches, and not greater than 96 inches.

u Maximum separation of appliances shall not exceed 100 feet.

ADAu The appliance shall be placed 80 inches above the highest floor level within the space, or 6 inches from the ceiling, whichever is lower.u Devices shall be no more than 50 ft. apart.u In large areas without obstructions 6 ft. above the floor, devices may be spaced a maximum of 100 feet apart.


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Visual Device Installation

96"

80"

At least 80"

At least 6"

NFPA

ADA 96"

80"

At least 80"

At least 6"

NFPA

ADA

Strobe Horn/Strobe

At least 90"


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Synchronizationu Visual Synchronization reduces the effect on those

who are prone to suffer seizures from Epilepsy.u Required when two or more appliances are in the

same field of view.


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Synchronization

u Synchronization is effected via two means - a remote module or circuitry built into the fire alarm control panel.

u Built-in control panel circuitry is highly desirable.

u Audible Synchronization permits the proper sounding of evacuation coding.


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Distributed NACsu Use of a remote power supply can save previous

voltage in the run from the control panel to the start of a Notification Appliance Circuit.


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Wiring Standards

u NFPA 72 establishes standards of performance for various wiring styles for Initiation Circuits, Notification Appliance Circuits and Signaling Line Circuit (SLC) Loop wiring.u For Initiating Device Circuits Styles B & D.u For Notification Appliance Circuits Styles Y & Z.u For SLC Loops Styles 4,6, & 7.


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u 2-wire circuit originates at the control unit, interconnects all devices in parallel fashion and terminates with an End-Of-Line Resistor.

u A wire break results in a loss of all devices past the break.

u No branch tapping allowed.

Style B/Style Y(Class-B type circuits)


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Class B-Type Circuit

FACP


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Style D/Style Z(Class-A type circuits)

u Wiring originates at the control unit, interconnects all devices in parallel fashion and returns to the control unit.

u Return circuit monitors line voltage. If voltage missing, return line will feed current to devices from its connections.

u No branch tapping allowed.


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Class A-Type Circuit

FACP


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u 4-wire Smoke Detectors are devices that receive power from a source other than the Initiating Device Circuit.

u They may be wired in Style B or Style D, and are supervised with an end-of-line power supervision relay for loss of operating current.

4 Wire Smoke Detectors


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4 Wire Detectors4-wire Smoke Detectors wired Style B

InitiatingZone

4-WireDetectorPower

IDC (+)

IDC (-)

+24VDC

Common

UL ListedPowerSupervisoryRelay


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Questions?


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Thank You for Attending!


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Terminologyu FACP - Fire Alarm Control Panel.u FACU - Fire Alarm Control Unit.u FCC - Federal Communications Commissionu UL - Underwriters Laboratoriesu NFPA - National Fire Protection Agency.u AHJ, LAHJ - Authority Having Jurisdiction, Local AHJu ADAAG - Americans with Disabilities Act Accessibility

Guidelines.u PoC - Products of Combustionu LED - Light Emitting Diodeu IDC - Initiating Device Circuitu NAC - Notification Appliance Circuitu ELR, EOL - End of Line Resistor


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Terminologyu NEC - National Electrical Code (NFPA 70)u NEMA - National Electrical Manufacturing Associationu EIA - Electronics Industry Associationu Cd - Candelau dB, dBA - Decibelsu FWR - Full Wave Rectifiedu ANSI - American National Standards Instituteu PIV - Post Indicator Valveu OS&Y - Outside Stem and Yoke Valvesu SFPE - Society for Fire Protection Engineersu Shall - Indicates a mandatory requirementu Should - Indicates a recommendation or advisement


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References

u NFPA 70 - National Electrical Codeu NFPA 72 - National Fire Alarm Codeu NFPA 101 - Life Safety Codeu National Electrical Code Handbook, NFPAu Life Safety Code Handbook, NFPAu Fire Protection Handbook, NFPAu Fire Alarm Signaling Systems, NFPA


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Additional References

u Guide for Proper Use of System Smoke Detectors, System Sensor.

u Guide for Proper Use of Smoke Detectors in Duct Applications, System Sensor.

u Guide for Proper Use of Projected Beam Smoke Detectors, System Sensor.

u Strobe Compliance Reference Guide, System Sensor.