Fire Alarm Flashcards
What are the 4 elements to a fire?
- fuel
- heat
- oxygen
- chemical chain reaction to above items
In fire fighting terms what is “Starvation?”
The process of depriving the fire of fuel, like combustible materials.
In fire fighting terms what is “Cooling?”
The process of depriving the fire of heat. For example, by applying water to a fire, you absorb the heat and reduce the temperature needed to support combustion.
In fire fighting terms what is “Smothering?”
The process of depriving the fire of oxygen
In fire fighting terms what is “Interference?”
The process of applying extinguishing agents, such as dry chemical, to stop the chemical chain reaction
What does Class A fire extinguisher fight?
Paper, Wood, Cloth, Ordinary combustibles
What does Class B fire extinguisher fight?
Flammable liquids such a diesel and gas
What does Class C fire extinguisher fight?
Energized Electrical Equipment fires
What does Class D fire extinguisher fight?
Metals such as magnesium, potassium, titanium
What does Class K fire extinguisher fight?
Cooking fires with oil and fat
What is water in a fire extinguisher good for fighting. How does it work?
Class A fires. Cooling
What is Foam in a fire extinguisher good for fighting. How does it work?
It separates oxygen from the other elements in the fire triangle by smothering the fire.
What is Carbon Dioxide in a fire extinguisher good for fighting. How does it work?
It removes the oxygen element and some heat with a very cold discharge. Generally, it is
effective on Class B and C fires, but not Class A fires.
What is Dry Powder in a fire extinguisher good for fighting. How does it work?
Interrupts the chemical chain reaction of the fire. The multipurpose dry chemical is the most widely used type of fire extinguisher and is effective on Class A, B, and C fires.
What is Wet Chemical in a fire extinguisher good for fighting. How does it work?
is a new agent that extinguishes the fire by removing the heat element and prevents re-ignition by creating a barrier between the oxygen and fuel elements. This type of extinguisher was developed for modern, high efficiency deep fat fryers in commercial cooking operations. Some may also be used on Class A fires in commercial kitchens.
The rating on the combination extinguisher is rated 4-A:80-B:C. What does this code mean?
The “A” rating is a water equivalency rating. Each “A” is equal to 1.25 gallons (4.73L)
of water. So 4A = 5 gallons (18.92L) of
water.
The “B:C” rating is equivalent to the amount of square footage that the extinguisher can
cover, handled by a professional. This extinguisher can cover 80 ft
The “C” rating never has a numeric value as it simply indicates that the chemicals inside
are non
-conductive
-suitable for use on energized electrical equipment
What does PASS method mean?
When using a fire extinguisher:
- Pull
- Aim
- Squeeze
- Sweep
What are the four stages to a fire?
- Incipient Stage
- Soldering (smoke) Stage
- Flame Stage
- Heat Stage
What is an IDC?
Initiating Device Circuit. Used to notify fire alarm panel that a fire sensing device (IE smoke detector) has triggered.
What is SDC?
Signalling Device Circuit. Alarm panel uses these to turn on bells and strobes etc.
What is FACU?
Fire Alarm Control Unit. The brains of the fire alarm system.
What are rules for Primary Power to Fire Alarm Control Unit (FACU?)
A fused circuit of 115V, 60 Hz located on the load side of the service and taken from as close to the incoming mains (meter) as is possible. A red painted fused disconnect or breaker labelled FIRE ALARM, able to be locked in the on-position, is required. [See CEC Rule 32-108 (1), (3)]
What are rules for Standby Power to Fire Alarm Control Unit (FACU?)
upon a loss of primary power lasting more than 15 seconds, the power source must be transferred to standby power. The FA system will immediately and automatically transfer back to the main power source upon its restoration. Standby power may be an emergency circuit from a generator or, more often, a battery bank found in the FA control unit itself. The standby power must be sized to provide supervisory (normal non-alarm) power for 24 hours, followed by full-load (alarm)
power for 5 minutes.
Where must the Annunciator Panel be located?
Building Front Entrance
What is an Ancillary Device?
Ancillary devices are building devices or components that are not part of the FA system but are controlled by it because they serve a life-saving function.
What is an Ancillary Device, Door Holder Release do?
Allows doors to close upon a fire alarm.
What is an Ancillary Device, Maglock Release do?
Allows maglocked doors to unlock and become open during a fire alarm.
What is an Ancillary Device, Elevator Recall or Capture do?
Sends elevators to ground floor and remain open for firefighters’ use.
What is an Ancillary Device, Damper Control do?
Damper Control
The FA system will close dampers to prevent fresh air from entering and feeding the fire,
and open other dampers to allow smoke to ventilate outside.
What is an Ancillary Device, Fan Controls do?
To control the spread of deadly smoke, the FA system will turn off fresh air fans and turn on exhaust fans. To stop smoke from entering stairwells, fans provide
fresh air and positive pressure to these areas during a fire alarm.
What does Auxiliary circuit do?
This term pertains to the automatic connection of the FA system in a building to a remote
monitoring service or directly to the fire department for certain public building
installations, such
as hotels, shopping centres, schools and hospitals. An auxiliary relay contact or a city
-tie module
(CTM) is included in the FACU for this purpose. Upon activation of any alarm on the system,
this relay will activate and send a signal to the monitoring service/fire department.
What is simplex communication?
The communication is like broadcast radio. It only goes in one direction.
What is Half-Duplex communication?
The communication can goes either direction. But only one direction at once. Like using a walkie-talkie.
What is Full-Duplex Communication?
The communication can go both ways at the same time. Just like a phone call.
How many strokes per minute for an Alert-Signal?
20
How many strokes per minute for an Alarm-Signal?
120
What is a single stage system?
An activated initiating device will sound a general alarm on all signal devices, warning all occupants to vacate the area immediately. These systems are
most common where people are able-
bodied and familiar with the exits, such as schools,
apartment building and industrial plants.
What is a Two stage system?
An alert signal will sound upon the operation of any initiating device, which serves to advise supervisory staff of a possible fire condition. This first-stage (alert stage) is limited to a maximum of 5 minutes before a general alarm sounds, allowing staff to investigate the source of the activation.
What is coded fire alarm?
When fire alarm sounds, within the first minute, tone patterns may indicate which zone has tripped. It can repeat four times. After which time general alarm signals.
What does Indicating mean for a fire alarm?
At the annunciator panel in the lobby it will indicate which zone or IDC was tripped. Causing the alarm.
Fire alarm zones, What is an Alarm Initiating zone?
Alarm initiating zones are circuits wired to field devices such as smoke or heat detectors, pull stations or sprinkler flow switches. Activation of these IDC zones will cause the audible signals to sound in accordance with the specific system operation stylelarm initiating zones are circuits wired to field devices such as smoke or heat detectors, pull stations or sprinkler flow switches. Activation of these IDC zones will cause the
audible signals to sound in accordance with the specific system operation style.
Fire alarm zones, What is a Supervisor Initiating zone?
Supervisory initiating zones are circuits wired to devices such as sprinkler valves, supervisory switches or sprinkler low-pressure sensors. Activation of these zone types will not cause the general alarm to sound, but will activate a supervisory condition in the
system.
Fire alarm zones, What is a Monitor Initiating zone?
Monitor initiating zones simply monitor the status of
devices such as fire dampers (open
or closed) or the condition of fans (on or off). Monitor zones do not activate SDC’s or issue system trouble signals, only annunciating their status via visual indicators.
What are benefits of having fire alarm zones?
What benefit is there in having zones within a
building? The concept of zones provides a number
of advantages and fire safety benefits, which is why they are required by Building Code.
Zones provide a logical breakdown by building area, making it easier and faster for
supervisory/maintenance personnel
to locate troubles or alarm signals.
Firefighting personnel can respond rapidly when the trouble area’s zone is known.
Zoning also provides a means to monitor the spread of fire, as smoke and flame may
progress from zone to zone
What things are defined as a fire alarm zone?
Each floor of up to 2000 m
Stairwells, garbage chutes and elevator shafts all require separate zones. Since these
shafts generally cut through several floors of a building and a fire could involve the entire
shaft, they cannot be connected to a specific floor’s zone.
Any room or area with a 2-hour fire resistant separation requires a separate zone.
What is the supervisory current value in a fire alarm IDC circuit?
40ma
In a fire alarm system are IDC devices NO or NC?
NO
What voltage does a FACU IDC circuit run at?
24VDC
How many wires does a two-stage fire alarm pull station use?
4
Do you need a fire alarm pull station in a hallway of 200 feet or longer?
Yes
What two ways can heat detector detect fire?
Rate of rise and fixed temperature.
How does a restorable heat detector work?
Uses a bi-metalic strip to activate.
How does a non-restorable heat detector work?
Uses solder and spring mounted plunger.
What two things can cause a dual action heat-detector to trigger?
-Rate of rise
OR
-Fixed temperature
What is a rate-compensating heat detector application?
In a kitchen
How does a rate-compensating heat detector work?
It has a faster response time. Outer tube expands to do increasing temperature. Which causes inner contact to move closer together. When Alarm triggering threshold temperature is reached, the contacts close.
How does a linear heat detector work?
Two steel wires, twisted together with a heat sensitive polymer insulating them. During a fire the polymer melts causing a short circuit.
What smoke detector detects a stage 1 fire best?
Ionization type for stage 1 incipient fires
What smoke detector detects a stage 2 fire best?
Photoelectric type for stage 2 smoke fires
How does reflected type smoke detector work?
It relies on on the light scattering principal to reflect light off of smoke particles towards the sensor. Not fail-safe.
How does obscuration smoke detector work?
It relies on smoke absorbing light between emitter and detector. This is fail-safe.
How does projected beam smoke detector work?
A beam or IR and UV it transitted between emittor and detector. Up to 100M apart. When smoke crosses beam UV is blocked. When IR is blocked a trouble is created as something blocked the beam.
How does air duct mounted smoke detector work?
A pipe with holes is mounted within a duct. Air samples are taken and checked for smoke. Air samples returned to duct.
How to flame detectors work?
They look for IR and UV light signatures of the flame.
In fire alarm what is a SDC?
Signalling Device Circuit. IE Alarm bells, stobes
What is a single stroke bell?
A bell which sounds only by the circuit turning on and off quickly. Good for two stage fire-alarms.
What in a fire alarm speaker allows DC to not pass through to allow supervision circuit to work?
Capacitor. DC won’t flow through it. However AC will which will allow alarms and voice announcements.
What two wiring methods are used for fire alarm?
- Conventional
- Addressable
What consists of a Class B fire alarm system in regards to the IDC?
Normally Open IDC devices hooked up in parallel with a end-of-line resistor at the end of the circuit. All devices in this one circuit would be one zone. 2 wire system.
What consists of a Class A fire alarm system in regards to the SDC?
In non-alarm mode the Signalling Device Circuit (Speakers or Bells) operates in reverse bias and no power goes through the bell because of a diode, therefore power carries on to the end-of-line resister and comes back to the panel. In Alarm mode an internal relay in the fire alarm panel reverses the bias (polarity) through a relay so that the power goes forward bias through the bells causing them to ring.
Is class B fire alarm system know as radial or loop?
Radial
Is class a fire alarm system know as radial or loop
Loop
Does class A fire alarm systems use an EOLR End of Line Resister?
No, not at the end of the line. However it does exist within the fire alarm panel.
Can you T-tap a fire alarm cable?
Not ever in conventional class A & B systems. It defeats the line monitoring. However it can be done on manual addressable systems. But not automatic addressable systems.
What are 5 advantages in an addressable fire alarm system?
- greater flexibility for operational sequences such as timers, counters, logic functions
- reduced power requirements for hardware in the field
- reduced field wiring due to multiplexing
- greater ability to pinpoint alarms and troubles, as each device has a unique address
-easily expandable
systems
What are 3 disadvantages for an addressable fire alarm system?
- easily damaged by static electricity and power surges
- sensitive to electromagnetic interference or “noise” from power conductors
-incompatibility with other addressable
system manufacturers
What two questions are asked when FACU polls addressable devices?
Each addressable device has a unique address assigned to it and these devices are not only
recognized individually by the CPU, but interrogated or “polled” about their condition. One by one, the CPU asks each field device (in order) two questions:
Who are you?
What is your status?
How does automatic addressing work in fire alarm systems?
Upon system power-up, with devices on the data loop self-configuring in the order the panel recognizes
them.No T-tapping can be done.
How does manual addressing work in fire alarm systems?
Requires the setting of dials or dipswitches on devices, or it may entail keeping meticulous record of device barcodes for programming. This extra work is offset by the fact that devices may be T-tapped from any point on the data loop.
What do transponders do in a fire alarm system?
They segment the fire alarm system. A bunch of IDC in one zone will communicate with the transponder, and in turn the transponder will let the FACU know of any alarms or trouble. Therefore the FACU poll time will be quicker in very large systems. Also a transponder can activate a local alarm to the area it’s protecting thereby if there is a data problem between it and the FACU the local area is protected with a local alarm. When running in a local-mode we call it “Degraded Mode”
What do Line Isolaters do in a fire alarm system?
They segment each zone. Which should be max one floor or 2000 Sq Meters. With a max of 255 devices. As addressable systems run in a loop. If there is a break in the loop in the middle the line isolators will allow communications back through either side of the broken loop maintaining connectivity. If this happens they will provide a trouble condition to alert loop broken, and devices will still work.
During fire alarm system verification what percentage of devices need to be tested?
100%
Can you us a megger on a fire alarm system wiring.
Generally no. Unless extreme care it taken to isolate all devices and panels. Meggering high voltage will damage components.
When troubleshooting an Class B IDC in the field what are common errors?
- missing EOL resistor in the field
- missing shorting strip on ionization detector bases
- loose/broken termination on a device
Are fire alarm systems grounded?
No. Fire alarm wiring is typically ungrounded.
What is a major cause of fire alarm ground faults in parkades?
Water getting into boxes.
What is common wire size for fire alarm signal wires?
14 or 16 AWG. Section 32-100 in CEC
What minimum insulation rating in volts and temp for fire alarm cable?
300V 60C
What is smallest conductor size allowed for fire alarm cable?
22AWG in a four conductor cable.
Can fire alarm cable be run in the same raceways as other cable
No. It must be separate.
What is unique about power supply connection of a fire alarm?
- Must be it’s own breaker closest to the supply.
- Must be identified in red
- Breaker must be locked in “On” position.
Should smoke alarms be on their own dedicated circuit?
No. They must be on a shared lighting circuit. That way if breaker trips, homeowner will notice lights not working and restore power to lighting and smoke alarm circuit.
Is it okay to install smoke alarms on GFCI and AFCI circuits?
No. It’s not good practice.
At what temperature does fire begin?
350C
Describe the Incipient stage of a fire?
-No visible smoke, no flame and very little heat -A significant amount of invisible combustion particles are created -‘Slowest Stage’...becoming apparent
Describe the Smouldering stage of a fire?
- Smoke develops but no flame yet.
- Not much heat yet, but more than before.
- “A fire can smoulder for hours.”
Describe the Flame stage of a fire?
- Visible Flame appears now
- More Heat but often less or no smoke
Describe the Heat stage of a fire?
-Large amounts of heat and flame are present -moke and toxic gasses are also prevalent -The transition for Stage 3 to 4 is very fast! “Flashover”
Which of the four stages of a fire is the deadliest?
Smouldering. Oxygen consumed and replaced with toxic gases.
Normal air contains what % oxygen?
21%
What is the main purpose of a fire alarm system?
- Save Lives
2. Save property
What code determines the Fire Alarm system used in a building?
BC Building code.
What is a fire alarm NAC?
Notification Appliance Circuit, A USA term. In Canada we use the term Signalling Device Circuit.
Strobe lights in a Fire Alarm system flash at what rate?
1-3 Pulses Per Second.
What is an air aspirated detection system?
A smoke detector comprised of a series of pipes that suck air back to a central detector.
Why don’t you install sprinklers and heat detectors in the same room?
They have roughly the same trigger temperature. So there is no point. Sprinkler would go off and flow switch will set off alarm.
What is set-point of a heat detector?
57C normally 88C in a high heat area such as a boiler room.
What are spacing requirements of heat detectors?
-9M for non-restorable
-6M for fixed
-15M for combination
And half the metres to the wall.
With a heat detector what is the RTI?
Response Time Indicator. Value from 1-100
Lower number is faster response to heat detection.
In a fire extinguisher a Dry chemical agent is used for what class of fires?
A B C
In a fire In a fire extinguisher a Foam is used for what class of fires?
Airplane hangers. A B C D
Is fire code above electrical code?
Yes
What rate of rise in temperature triggers a rate-of-rise heat detector.
over 8C per minute
How high would you mount a projected beam smoke detector in an atrium?
3/4 the height of the space
What must be done to cause a single stroke bell to ring continuously?
FACU must pulse power circuit to bell to cause it to ring continuously.
What is common to Soleniod and Motor driven bells?
They both have FACU deliver continuous power to continually ring bells.
What electronic component does a Voice Paging system for a fire alarm system use to provide electrical supervision to the circuit?
A capacitor. It blocks DC so that current makes it to EOLR and back. During voice paging system uses AC which passes through the capacitor.
How many wires in a Class B circuit
2
How many wires in a Class A circuit
4
Does a duluge sprinkler system have thermally triggered sprinkler heads?
No. Sprinkler heads are open.
True/False The Tamper switch of a flow switch is in series with the EOLR, located after the flow switch
True
