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Fire detection systems Flashcards

1
Q

Introduction to Fire detection systems

A

a. Fire prevention and building codes require that most new structures have some sort of fire protection system installed. Currently we use the IFC Chapter 903, IBC Chapter 903, NFPA 13 and NFPA 72 for requirements
b. Understanding how these systems operate is important for fire fighter safety and effective customer service

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2
Q

From a safety standpoint, why are fire detection surpression systems good?

A

i. The operations and limitations of fire detection and suppression systems (Fire Sprinklers systems are effective in controlling fires 96% of the time.)

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3
Q

From a customer service standpoint, what should we be doing with regards to fire protection systems

A

i. Help dispel misconceptions about fire protection systems

ii. Advise building owners and occupants after an alarm is sounded

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4
Q

What are FPS (fire protection systems) like across america?

A

i. Most areas follow the applicable NFPA standards

ii. Local fire prevention and building codes may require different types of systems for different buildings

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5
Q

What are the IFC, IBC, and NFPA requirements for FPS?

A

IFC Chapter 903,
IBC Chapter 903, NFPA 13 and
NFPA 72

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6
Q

What is a fire alarm and/or detection system?

A

a. A fire detection system recognizes when a fire is occurring and activates the fire alarm system
i. Alerts occupants (saving lives primary purpose)
ii. May alert the fire department
iii. May automatically activate fire suppression systems
iv. Secondary purpose is to conserve property
b. Fire alarm and detection systems can be very simple or very complex
i. These systems generally have the same basic components

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7
Q

Residential fire alarm systems

A

a. Single-station smoke alarm most common type of residential fire alarm system
b. Includes both a smoke detection device and an audible alarm within a single unit
c. Millions installed in private dwellings and apartments
d. Smoke alarms can be battery-powered or hard-wired to a 110 volt electrical system
e. Up-to-date codes require new homes to have a smoke alarm in every bedroom and on every floor level
f. Many home fire alarm systems are part of security systems

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8
Q

Ionization Versus Photoelectric Smoke Detectors

A

a. Ionization detectors are triggered by the invisible products of combustion
b. Photoelectric detectors are triggered by the visible products of combustion

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9
Q

Fire Alarm System Components

A

a. Three basic components in a fire alarm system
i. Alarm initiation device
ii. Alarm notification device
iii. Control panel

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10
Q

Fire Alarm System Control Panels

A

i. Serves as the “brain” of the system
ii. Manages and monitors the proper operation of the system
iii. Can indicate the source of an alarm
iv. Also manages primary power supply and provides backup power supply for the system
v. May perform additional functions, and may interface with other systems and facilities
vi. Vary greatly depending on age of system and manufacturer
vii. Used to silence the alarm and reset the system
viii. Many buildings have an additional display panel, called a remote annunciator in a separate location. Near the main entry way or lobby is a good location. Near the main entry way or lobby is a good location for Annunciator panels
ix. A battery in the fire alarm control panel will automatically activate when the external power is interrupted

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11
Q

Alarm Initiating Devices

A

i. Components that activate a fire alarm system
ii. Manual initiation devices require human activation
iii. Automatic devices function without human intervention

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12
Q

Manual initiating devices

A

i. Designed so that building occupants can activate the fire alarm system
ii. Primary manual initiation device is the manual fire alarm box, or manual pull- station
iii. Once activated, should stay in the “activated” position until it is reset
iv. Double-Action Pull Stations
1. Variation on the double-action pull-station, designed to prevent malicious false alarms, is covered with a piece of clear plastic
2. Often used in areas where malicious false alarms frequently occur

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13
Q

Automatic initiating devices

A

i. Deigned to function without human intervention
ii. Can use several different types of detectors
iii. Some detectors activated by smoke or by invisible products of combustion
iv. Others react to heat, light produced by an open flame, or specific gases

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14
Q

Smoke detectors

A
  1. Designed to sense the presence of smoke
  2. Commonly found in schools, hospitals, businesses, and commercial occupancies with fire alarm systems
  3. Most common are ionization (Invisible products of combustion) photoelectric detectors
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15
Q

Heat detectors

A
  1. Can provide property protection, but cannot provide reliable life safety protection
  2. Generally used in situations where smoke alarms cannot be used
  3. Often installed in unheated areas
  4. Generally very reliable an less prone to false alarms than smoke alarms
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16
Q

Fixed tempurature detectors

A

a. Designed to operate at a preset temperature

b. Usually use a metal alloy that will melt at the preset temperature

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17
Q

Rate of rise detectors

A

a. Will activate if the temperature of the surrounding air rises more than a set amount in a given period of time
b. Most rate-of-rise heat detectors are self-restoring
c. Generally respond faster to most fires than fixed-temperature heat detectors

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18
Q

line heat detectors

A

a. Use wires or a sealed tube to sense heat
b. One type has two wires inside, separated by an insulating material
c. Another type measures changes in the electrical resistance of a single wire as it heats up
d. The tube-style line heat detector has a sealed metal tube filled with air or a nonflammable gas

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19
Q

Flame detectors

A
  1. Specialized devices that detect the electromagnetic light waves (Infrared or Ultraviolet) produced by a flame
  2. Typically found in places where early detection and rapid reaction to a fire is critical
  3. Complicated and expensive
  4. Arc welding can cause accidental activation of ultraviolet flame detectors
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20
Q

Gas detectors

A
  1. Calibrated to detect the presence of a specific gas
  2. Needs regular calibration
  3. Usually found only in specific commercial or industrial applications
  4. Gases released by a fire that a detector would sense are Carbon Monoxide, Carbon Dioxide, Hydrogen Chloride, Hydrogen Cyanide, Hydrogen Fluoride and Hydrogen Sulfide
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21
Q

Air Sampling detectors

A
  1. Continuously capture air samples and measure the concentrations of specific gases or products of combustion
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22
Q

Alarm Initiation By Fire Suppression Systems

A

a. Systems alerts building occupants and the fire department to a possible fire
b. Water Flow Alarm ensures that someone is aware water is flowing from a sprinkler head or when a standpipe valve is opened

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23
Q

False, Unwanted, and Nuisance Alarms

A

a. Malicious False Alarms
i. Caused by individuals who deliberately activate a fire alarm when there is no fire
b. Unwanted Alarms
i. Occur when an alarm system is activated by a condition that is not really an emergency
c. Nuisance Alarms
i. Caused by improper functioning of an alarm system or one of its components

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24
Q

Alarm Notification Appliances

A

a. Produce an audible signal when fire alarm is activated ( Bells, horns, speakers)
b. Some signals play a recorded announcement in conjunction with the temporal – 3 pattern
c. Many new systems incorporate visual notification devices

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25
Q

Other fire alarm functions

A

a. May also control other building functions, such as air handling systems, fire doors, and elevators
b. Responding fire personnel must understand which building functions are being controlled by the fire alarm

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26
Q

Fire Alarm annunciation systems

A

a. Almost all alarm systems are now zoned to some extent
b. In a coded system, zone is identified not only at the alarm control panel but also through audio notification device
c. Systems can be broken down into four categories, non-coded alarm, zoned non-coded alarm, zoned coded alarm, and master-coded alarm

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27
Q

Non-coded alarms

A

i. Control panel has no information indicating where in the building the fire alarm was activated
ii. Typically sounds a bell or a horn
iii. Fire department personnel must search the entire building to find which initiation device was activated

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28
Q

Zoned non-coded alarms

A

i. Most common type of system, particularly in newer buildings
ii. Building divided into multiple zones, often by floor or by wing
iii. Alarm control panel indicates in which zone the activated device is located

29
Q

Zoned Coded alarms

A

i. In addition to having all the features of a zoned alarm system, also indicates which zone has been activated over the announcement system
ii. Hospitals often use this type of system

30
Q

Master coded alarms

A

i. Audible notification devices for fire alarm also are used for other purposes
ii. Most of these systems have been replaced by modern speaker systems that use the temporal-3 pattern fire alarm signal and have public address capabilities

31
Q

Fire Department notification systems

A

Fire alarm systems can be broken down into four classifications, based on how the fire department is notified of an alarm

a. Local alarm system
b. Remote station system
c. Proprietary or Auxiliary system
d. Central station

32
Q

Local alarm system

A
  1. Does not notify the fire department

2. The alarm sounds only in the building to notify the occupants

33
Q

Remote station system

A
  1. Sends signal directly to fire department or to another monitoring location via a telephone line or a radio signal
34
Q

Auxilary system

A
  1. Building’s fire alarm system is tied into a master alarm box located outside
35
Q

Proprietary system

A
  1. Building’s alarms connected directly to monitoring site owned and operated by building owner
36
Q

Central Station system

A
  1. Third-party, off-site monitoring facility that monitors multiple alarm systems
  2. An activated alarm transmits a signal to the central station by telephone or radio
  3. Personnel at the central station then notify the appropriate fire department of the fire alarm
37
Q

Fire Supression systems

A

a. Include automatic sprinkler systems, standpipe systems, and specialized extinguishing systems such as dry chemical systems
b. Understanding how these systems work is important because they can affect fire behavior

38
Q

Automatic sprinkler systems

A

i. One of the major advantages of a sprinkler system is that it can function as both a fire detection system and a fire suppression system
ii. Closed valves, inadequate water supply, blocked heads, fire load changes, partial protection and poor maintenance are reasons systems fail
iii. Sprinkler system defined is “ A system of pipes, valves, water, and heads, which operate automatically to control or extinguish fire, initiate an alarm, save lives and property”

39
Q

Automatic Sprinkler System Components

A

i. Four major components
1. Automatic sprinkler heads
2. Piping
3. Control Valves
4. A water supply, which may or may not include a fire pump

40
Q

Automatic Sprinkler Heads

A
  1. The working ends of a sprinkler system
  2. Composed of
    a. A body, which includes the orifice (openings)
    b. A release mechanism that holds a cap in place over the orifice
    c. A deflector that diverts the water in a spray pattern
41
Q

iii. Frangible Sprinkler Heads

A
  1. Use a glass bulb filled with glycerin or alcohol to hold the cap in place
    a. As the bulb is heated, the liquid absorbs the air bubble and expands until it breaks the glass, releasing the cap
42
Q

Chem-pellet sprinkler heads

A
  1. Use a plunger mechanism and a small chemical pellet to hold the cap in place
    a. Pellet will liquefy at a preset temperature
    b. When pellet melts, liquid compresses the plunger, releasing the cap and allowing the water to flow
43
Q

Special sprinkler heads

A
  1. Designed for special applications
    a. Covering large areas
    b. Discharging the water in extra-large droplets
  2. ESFR sprinkler heads have improved heat collectors to speed up response and ensure rapid release
44
Q

Deluge heads

A
  1. Easily identifiable, because they have no cap or release mechanism
  2. Orifice is always open
  3. Only used in deluge sprinkler systems
  4. Deluge systems are designed to protect hazardous occupancies
45
Q

Temperature ratings

A

a. Typical rating for sprinkler heads in a light hazard occupancy would be 165 degrees F. (74C)
b. Rating should be stamped on the body of the sprinkler head
c. Temperature rating must match the anticipated ambient air temperatures
d. Spare heads that match those used in the system should always be available on-site
e. Uncolored or black sprinkler heads have an operating temperature of 135-170 degrees F.

46
Q

Sprinkler piping

A

a. Network of pipes that delivers water to sprinkler heads
b. Includes main water supply lines, risers, feeder lines, and branch lines
c. Usually made of steel
d. Plastic pipe sometimes used in residential systems

47
Q

Valves

A

a. A sprinkler system includes several different valves such as:
i. Main water supply control valve
ii. Alarm valve
iii. Other, smaller valves used for testing and service
b. All of the valves play a critical role in the design and function of the system

48
Q

Water supplies

A

a. Water may come from municipal water system, on-site storage tanks, or static water sources
b. Water supply must be able to handle demand of the sprinkler system, as well as the needs of the fire department
c. Preferred water source for a sprinkler system is a municipal water supply
d. Retard chambers can be added to fire sprinkler system risers to help reduce false alarms due to momentary water surges

49
Q

Fire pumps for sprinklers

A

a. Used when the water comes from a static source

b. May also be used to boost the pressure in some sprinkler systems, particularly for tall buildings

50
Q

Fire department connections FDC

A

a. Allows the department’s engine to pump water into the sprinkler system
b. Used as either a supplement or the main source of water
c. Water Flow Alarms
d. Most systems incorporate a mechanical flow alarm called a water-motor gong
e. When system is activated and main alarm valve opens, water is fed through a pipe to a water-powered gong located outside the building

51
Q

Types of automatic sprinkler systems

A

a. Divided into five categories
i. Wet sprinkler systems
ii. Dry sprinkler systems
iii. Pre-action sprinkler systems
iv. Deluge sprinkler systems
v. Residential
vi. Coverage of systems could be complete or partial

52
Q

Wet sprinkler systems

A

i. Most common and the least expensive type of automatic sprinkler system
ii. Piping always filled with water
iii. As sprinkler head activates, water is immediately discharged onto the fire
iv. Major drawback, cannot be used in areas where temperatures drop below freezing
v. Will also flow water if a sprinkler head is accidentally opened or a leak occurs in the piping

53
Q

Dry sprinkler systems

A

i. Operate much like wet sprinkler systems, except that the pipes are filled with pressurized air instead of water. Used in areas subject to freezing
ii. A dry-pipe valve keeps water from entering the pipes until the air pressure is released

54
Q

Pre-action sprinkler systems

A

i. Similar to a dry sprinkler system with one key difference
1. A secondary device (smoke or heat detector) must be activated before water is released into the sprinkler piping.
2. When the system is filled with water, if functions as a wet sprinkler system

55
Q

Deluge sprinkler systems

A

i. Water flows from all of the sprinkler heads as soon as the system is activated
ii. Does not have closed heads that open individually at the activation temperature, all of the heads in a deluge system are always open

56
Q

Residential sprinkler systems

A

a. Relatively new, but many homes now being built include them
b. Typically use smaller piping and sprinkler heads with smaller orifices and less water discharge

57
Q

Shutting down sprinkler systems

A

a. Order to shut down sprinkler system should come only from the IC
b. In most cases, system can be shutdown by closing main control valve such as one of the following, OS&Y, PIV, WPIV, or PVIA
c. Placing a wooden wedge or a commercial sprinkler stop into the sprinkler head can quickly stop the flow of water
i. This will not work with all types of heads

58
Q

Standpipe systems

A

a. Network of pipes and outlets for fire hoses built into a structure to provide water for firefighting purposes
b. Usually used in high-rise buildings, although they are found in many other structures as well

59
Q

Standpipe classification

A

c. Class I Standpipes
i. Designed for use by fire department personnel only
ii. Each outlet has a 2 ½” male coupling and a valve to open the water supply after the hose is connected
d. Class II Standpipes
i. Outlets generally equipped with a length of 1 ½” single-jacket hose pre-connected to the system
ii. Intended to enable occupants to attack a fire before the fire department arrives, but safety and effectiveness is questionable
e. Class III Standpipes
i. Have the features of both Class I and Class II standpipes in a single system
ii. Have 2 ½” outlets for fire department use as well as smaller outlets with attached hoses for occupant use
iii. Fire fighters should use only the 2 ½” outlets, even if they are using an adapter to connect a smaller hose

60
Q

Water flow in standpipe systems

A

a. Actual flow depends on the water supply, as well as on the condition of the piping system and fire pumps
b. Flow-restriction devices or pressure-reducing valves often installed at outlets to limit pressure and flow
i. If not properly installed and maintained, these devices can cause problems for fire fighters

61
Q

Water supplies in standpipe systems

A

a. Wet standpipe systems in modern buildings are connected to a public water supply with an electric or diesel fire pump to provide additional pressure
b. Most dry standpipe systems do not have a permanent connection to a water supply, so the FDC must be used to pump water into the system

62
Q

Special extinguishing systems

A

a. Specialized extinguishing systems are often used in areas where water would not be an acceptable extinguishing agent
- dry chem
- wet chem
- clean agent
- Carbon dioxide

63
Q

Dry chem extinguishing systems

A

i. Use the same types of finely powdered agents as dry chemical fire extinguishers
ii. Agent kept in self-pressurized tanks or in tanks with an external cartridge of carbon dioxide or nitrogen that provides pressure when the system is activated

64
Q

Wet chem extinguishing systems

A

i. Used in most new commercial kitchens
ii. Use a proprietary liquid extinguishing agent
1. Much more effective on vegetable oils than the dry chemicals used in older kitchen systems

65
Q

Clean agent extinguishing systems

A

i. Often installed in areas where computers or sensitive electronic equipment are used, or where valuable documents are stored
ii. Nonconductive and leave no residue
iii. Halogenated agents or carbon dioxide are generally used
iv. Operate by discharging a gaseous agent into the atmosphere at a concentration that will extinguish a fire
v. If there is a fire, the clean agent system should be completely discharged before fire fighters arrive
vi. Should be tied to building’s fire alarm system and indicated as a zone on the control panel
1. Alerts fire fighters that they are responding to a situation where a clean agent has discharged

66
Q

Carbon Dioxide extinguishing systems

A

i. Designed to protect a single room or a series of rooms

ii. Should be connected to the building’s fire alarm system

67
Q

Initiating devices for special extinguishing systems

A

i. Fusible links are placed above the target hazard to activate extinguishing systems
ii. Manual discharge pull station is also provided so that workers can activate the system if they discover a fire

68
Q

Extinguishing systems summary

A

a. All firefighters must have a general understanding of how fire protection systems function
b. Firefighters will respond to more false alarms in their careers than actual fires
c. Although it is not the firefighter’s job to maintain fire protection systems, firefighters should be able to advise the public on how to restore systems to service
d. Regardless of how sophisticated a fire protection system is, a serious fire can still occur
e. It is every firefighter’s job to try to limit water damage from the activation of a sprinkler system
f. Firefighter’s must understand the potential shortcomings of using a standpipe system to prevent injuries and fatalities

TFD (39 decks)

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