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Electrical - Level 4 > Fire Alarm > Flashcards

Fire Alarm Flashcards

1
Q

what are the basic components of a fire alarm system?

A
  • Initiating Device
  • Alarm/Signalling device
  • Control Panel (Fire Alarm control unit)
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2
Q

List some examples of Initiating devices

A
  • Smoke detectors
  • Heat detectors
  • Pull stations
  • Flame detectors
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3
Q

List some examples of signalling devices.

A
  • Bells
  • Horns
  • Strobes
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4
Q

What does the FACU contain?

A

Power supply and circuitry for operating, monitoring and troubleshooting

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5
Q

What is the Annunciator Panel and where is it typically located?

A

It is a monitoring panel to indicate the location or zone of the fire or trouble. Usually at main entrance and is graphical

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6
Q

List some examples of Ancillary devices.

A
  • Fan shutdowns
  • Fan start-ups
  • Fire door magnets
  • Door lock releases
  • Elevator homing
  • Plenum dampers
  • Fire phones
  • City tie module (CTM)
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7
Q

How does simplex communication work?

A

One way only

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8
Q

How does Half duplex communication work?

A

Both ways but only one at a time

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9
Q

How does full duplex communication work?

A

Both ways at the same time

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10
Q

How does a single stage system work?

A

any initiating device will cause all signalling devices to be activated

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11
Q

Where are single stage system recommended to be used?

A
  • Schools
  • Apartments
  • Warehouses
  • Industrial Plants
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12
Q

How does a two stage system work?

A

Any initiating device will first activate an alert signal for 2 - 5 - 15 mins and if not responded to then a general alarm will sound

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13
Q

Where are two stage systems used?

A
  • Hospitals
  • Rest homes
  • Hotels
  • Department stores
  • AIrports
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14
Q

What is the alert signal for in a two stage system?

A

It is for designated persons who may activate the general alarm when they deem necessary. allows supervisory staff to investigate and plan for an orderly evacuation.

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15
Q

What is required for a two stage system?

A

Trained personal 24 hours/day

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16
Q

How long is the first alert signal? How long is the full alarm?

A

First alert = 20 bell strokes/min

Full alarm = 120 bell strokes/min

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17
Q

Where are usually all two stage and some single stage systems linked to?

A

the fire department for a faster response

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18
Q

What is a zone in buildings FA system?

A
  • Defined location that is covered by initiating devices on one circuit (non addressable)
  • Defined area with assigned initiating devices (addressable)
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19
Q

What typically determines the number of zones?

A

size of the building

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20
Q

How many zones do hospitals have?

A

100+

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21
Q

How many zones do nursing homes have?

A

2 per floor

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22
Q

What is A.H.J. ?

A

Authority having Jurisdiction

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23
Q

How do Pull stations work?

A
  • Use a normally open single pole switch operated by a pull handle
  • Glass or brittle plastic rod is used to indicated which station has been pulled
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24
Q

How do two stage pull stations work?

A
  • Have a key operated switch along with the handle
  • Handle initiates the alert
  • Key switch initiates the alarm
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25
Q

Where are pull stations only key operated?

A
  • Mental health facilities
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26
Q

What are the types of heat detectors?

A
  • Fixed temp.

- Restorable or Unrestorable

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27
Q

What are common temps of fixed temp. detectors?

A
  • 58 degrees C/135 degrees F

- 90 degrees C/194 degrees F

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28
Q

How does a restorable type heat detector work?

A
  • Bimetallic strip causes contact closure when it bends due to temp. rise
  • When temp. falls, contact opens
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29
Q

How does a non-restorable heat detector work?

A
  • Heat causes solder pot to melt causing a spring loaded set of contacts to close
  • No means to reset when temp. falls
  • Center red disk indicates tripped
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30
Q

How do rate of rise detectors work? How is the response time compared to Fix detectors?

A
  • Designed to operate any time the temp. of ambient air rises more than 9 degrees C/14 degrees F per minute
  • Provide a faster response time than fixed detectors
  • Not suitable in areas which see rapid temp. changes
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31
Q

What is a Combination heat detector?

A

Dual action combining fixed and rate of rise

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32
Q

How does a Line type heat detector work?

A
  • Not a “spot type” device

- Heat sensitive polymer melts and shorts two conductors or a thermistor core conducts

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33
Q

What does a Line type heat detector protect?

A

Protects long areas such as:

  • cable trays
  • floating roofs of fuel tanks
  • suppression usually accompanies alarm
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34
Q

Where should heat detectors only be used? Why?

A
  • Where property protection alone is required
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35
Q

What are some characteristics of heat detectors?

A
  • Not a life safety device
  • mount in the ceiling
  • elevator shafts
  • Heat detectors on FA system in units, smokies in common halls
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36
Q

What provides the earliest warning of a fire condition?

A

Smoke Detectors

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37
Q

What are the main types of smoke detectors?

A
  1. Photoelectric detector
  2. Ionization type AKA “product of combustion”
  3. Beam type
  4. UV/IR (Fire Eyes) Detector
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38
Q

What do photoelectric detectors use and require?

A
  • Use a light source and light detector

- Require visible smoke to operate

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39
Q

What do photoelectric detectors detect?

A

2nd stage of a fire (smouldering)

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40
Q

How do photoelectric detectors work? where are they installed?

A
  • Smoke entering chamber affects beam of light cause a n.o. contact to close
  • Installed in bedrooms & hallways
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41
Q

What are the two types of Photoelectric detectors? which is best and why?

A
  1. Light scattering

2. Light obscuration (best, fail safe)

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42
Q

What do Ionization detectors detect?

A

1st stage of a fire (incipient)

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43
Q

How do Ionization detectors work?

A
  • Very sensitive, can be triggered by invisible smoke
  • Small amount of radio active material between 2 plates
  • If particles of invisible or visible smoke enter the chamber current flow is interrupted cause n.o. contacts to close
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44
Q

Under normal operation, what flows in Ionization detectors and how much of it?

A
  • ionization current

- 1 x 10 to the -12 amps

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45
Q

Where should ionization detectors not be used? What may activate them?

A
  • Areas of high humidity, dust or vapours
  • Garages
  • Air pollution and fog may activate them
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46
Q

What can some ionization detectors be tested with?

A

a magnet

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47
Q

Where are beam type detectors used?

A
  • Very long and tall rooms where smoke may not reach ceiling due to stratification
48
Q

How do beam type detectors work? What are the two ways of wiring them?

A
  • Transmit light across room to detect smoke
  • Reflective type has wiring at only one end (not good for narrow spaces less than 1 m away from trusses, etc..
  • End to end needs wiring to transmitter and receiver (better for narrow spaces)
49
Q

What do UV/IR detectors detect?

A
  • Stage 3 detector (flame stage)
50
Q

What usually accompanies UV/IR detectors?

A

suppression

51
Q

What are UV/IR detectors best at detecting?

A
  • Flammable liquid fires
  • UV detects natural gas, butane, propane (blue flames)
  • IR detects gasoline, jet fuel, and diesel (red flames)
52
Q

List some things signalling detectors can be represented as?

A
  • Audible
  • Visual
  • Odour based
  • Mechanical
53
Q

List some vibrating bell properties

A
  • Sizes = 4”, 6”, 8”, 10” (most common)
  • Sound level proportional to diameter
  • Usually 24Vdc or could be 120Vac
  • Uses solenoid and plunger to strike a bell
54
Q

What current does the FA control unit use?

A

40 mA thru a closed loop

55
Q

What are some Class A circuit properties?

A
  • Wiring starts and ends at the panel
  • Requires twice as much wiring as Class B
  • Will still function if an open occurs in a conductor
56
Q

What are some properties of a Class B circuit?

A
  • Wiring starts at panel and ends at the E.O.L

- E.O.L. values differ between initiating and signalling zones and between manufacturers

57
Q

What are Class C circuits?

A

Ancillary

58
Q

What are some properties of Signalling Circuits? What does each device incorperate? What voltage do they operate on?

A
  • Typically operate on 24Vdc
  • Each signally device incorperates a diode which blocks supervisory current when not an alarm
  • If panel goes to alarm, zone polarity is reversed on signalling circuits by the panel putting the devices into action
59
Q

What is the transition stage between stages 2 and 3 called?

A

Flashover - happens very fast

60
Q

What 4 basic conditions must there be for a fire to start?

A
  1. fuel
  2. heat
  3. oxygen
  4. chain reaction
61
Q

What is a Class A fire?

A

ordinary combustibles such as wood, paper, etc..

62
Q

What is a Class B fire?

A

flammable or combustible vapours such as gas

63
Q

What is a Class C fire?

A

electrical fires

64
Q

what is a class D fire?

A

combustible metals such as magnesium

65
Q

What does PASS stand for a fire extinguisher?

A
  1. Pull
  2. Aim
  3. Squeeze
  4. Sweep
66
Q

What is a type 1 FA system?

A

1-stage, Non indicating, non-zoned, general alarm

67
Q

what is a type 2 FA system?

A

1-stage, Indicating, Zoned, General alarm

68
Q

what is a type 3 FA system?

A

1-stage, indicating, zoned, coded, general alarm

69
Q

what is a type 4 FA system?

A

2-stage, indicating, zoned, alert/alarm

70
Q

what is a type 5 FA system?

A

2-stage, indicating, zoned, coded, alert/alarm

71
Q

How are addressable system controlled?

A

microprocessors

72
Q

How are field devices supervised?

A

digitally

73
Q

What does the processor do in addressable systems?

A

Polls each device with its own unique digital/binary address

74
Q

Manufacturers systems are _________?

A

Proprietary (top secret)

75
Q

Why does the CPU poll each device?

A

For its state of health (if its okay, in trouble, or in alarm)

76
Q

What happens if the CPU does not get a response?

A

it goes into trouble condition

77
Q

How are device addresses assigned?

A
  • dip switches or rotary dials
  • with a laptop via control panel
  • automatically by the FACU
  • one by one with portable handheld program
78
Q

how often is each device polled?

A

at least once per second

79
Q

What wiring may addressable systems require?

A

twisted shielded wiring for the devices

80
Q

What may some devices require in an addressable system?

A

external power

81
Q

What are fire alarm isolators?

A

they remove sections of zones in event of failure so remaining zones can still function

82
Q

What are the 4 types of sprinkler system? which has the fastest response time?

A
  1. Wet-pipe (fastest)
  2. Dry-pipe
  3. Pre-action
  4. Deluge
83
Q

Where are wet-pipe systems used?

A

ordinary combustibles where freezing is no worry

schools, hospitals, offices

84
Q

What do Jockey pumps do? What do they reduce?

A

Boost water pressure on sprinkler side of the check valve. Reduces false alarms cause by water hammering

85
Q

Where are dry-pipe systems used? What do the pipes contain?

A

ordinary combustibles where freezing is a problem
(parkades, warehouses, unheated structures)
Pipes contain air or nitrogen

86
Q

How much surface area does the dry side have compared to the wet side of a dry pipe system?

A

3-5 times the surface area

87
Q

What is a Pre-Action system?

A

a dry-pipe system where the water is held back by an electronically controlled valve connected to the FACU

88
Q

When will water enter the system pipes in a pre-action system? how is each head activated?

A

Only after the fire detection system is activated. Each head is activated individually

89
Q

Where are Pre-Action systems good for?

A

where accidental discharge of sprinklers would cause extensive damage (data centers, libraries)

90
Q

How can you describe the operation of a Pre-Action system?

A

Double interlocked

  • broken sprinkler head
  • IDC activation
91
Q

What are Deluge systems designed for?

A

High hazard areas

92
Q

How do deluge systems work?

A

Pipes are dry and unpressurized with heads open, connected to a water source being held back by a valve

93
Q

What happens when a Deluge system detects a fire? What agents do they use?

A

water is pumped thru the pipes and discharged thru the open heads. Majority use foam-based agents.

94
Q

What are the range of heights permitted for a pull station?

A

1.05 to 1.15 m

95
Q

what is the minimum height permitted for a fire bell?

A

1.8 m to center

96
Q

max height for an annunciator?

A

2.4m

97
Q

max height for a control panel?

A

2.4 m

98
Q

max height for an E.O.L.?

A

1.8 m to top

99
Q

what is the NBC?

A

national building code

100
Q

what is the ULC? what must all FA devices carry?

A

Underwriters Laboratories of Canada

ULC sticker

101
Q

what is the NFC?

A

national fire code

102
Q

who has the final say in the installation of a FA system?

A

fire marshall

103
Q

what is the regulatory body that determines which buildings require FA systems?

A

National building code

104
Q

what is the maximum height of audible signal appliances?

A

manufacturers recommendation

105
Q

where are E.O.L.’s usually located

A

beyond the last initiating or signalling device

106
Q

What is an ancillary device?

A

device actuated by the FA system but is not required to be part of the FA system

107
Q

What is electrical supervision?

A

a means whereby a fault condition that would interfere with the operation of a circuit is detected

108
Q

what is an annunciator?

A

device to visually indicate a signal received from the system

109
Q

give 3 examples of a “zone”

A
  • electrical room
  • north stairwell
  • second floor
110
Q

What is a method of psychological deterrent used to discourage tampering with a pull station?

A
  • Mirror

- Ink spray

111
Q

What is a method of testing a self-restoring type of thermal detector?

A

place approved heat source next to it

112
Q

What two possibilities may exist in an initiating cct when an ohmmeter reads a short (approx 0) ?

A

device tripped, conductors shorted

113
Q

where are single stroke bells most commonly utilized?

A

where key personal can hear

114
Q

what type of battery is used as a standby power supply?

A

rechargeable (gel-cell)

115
Q

what is the purpose of an E.O.L. ?

A

to permit supervisory current to flow

Electrical - Level 4 (8 decks)

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