Essentials of Fire Fighting, 5 th Edition Chapter 16 Fire Detection, Alarm, and Suppression Systems...

Essentials of Fire Fighting, 5th Edition

Chapter 16 — Fire Detection, Alarm, and Suppression

Systems

Firefighter II

Firefighter II16–2

Chapter 16 Lesson Goal

• After completing this lesson, the student shall be able to operate different types of fire detection, alarm, and suppression systems and identify the different types of alarm and auxiliary systems following the policies and procedures set forth by the authority having jurisdiction (AHJ).

Firefighter II16–3

Specific Objectives

1.Describe types of heat detectors. 2.Describe types of smoke detectors/alarms. 3.Explain how flame detectors and fire-gas detectors operate.

(Continued)

Firefighter II16–4

Specific Objectives

4.Discuss combination detectors and indicating devices. 5.Describe types of automatic alarm systems. 6.Discuss supervising fire alarm systems and auxiliary services.

(Continued)

Firefighter II16–5

Specific Objectives

7.Describe the operation of an automatic fire sprinkler system. 8.Discuss water supply for sprinkler systems. 9.Describe major applications of sprinkler systems.

Firefighter II16–6

Fixed-Temperature Heat Detectors

• Relatively inexpensive compared to other types of systems

• Can be slowest to activate• Activate when heated to

temperature for which rated

(Continued)

Firefighter II16–7

Fixed-Temperature Heat Detectors

• Installed in highest portions of room

• Should have activation temperature rating slightly above highest ceiling temperatures normally inspected in space

(Continued)

Firefighter II16–8

Fixed-Temperature Heat Detectors

• Activate by one or more of three mechanisms

• Fusible device• Frangible bulb• Continuous line

detector

Firefighter II16–9

Rate-of-Rise Heat Detectors

• Operate on assumption that temperature in room will increase faster from fire than from normal atmospheric heating

• Designed to initiate signal when rise in temperature exceeds 12° to 15°F (-11°C to -9°C) in one minute (Continued)

Firefighter II16–10

Rate-of-Rise Heat Detectors

• Can be initiated at room temperature far below that required for initiating fixed-temperature device

• Reliable, not subject to false activations

• Pneumatic rate-of-rise spot detector (Continued)

Firefighter II16–11

Rate-of-Rise Heat Detectors

• Pneumatic rate-of-rise line detector• Rate-compensated detector• Thermoelectric detector

Firefighter II16–12

Smoke Detectors

• Detect presence of smoke; must transmit signal to another device that sounds alarm

• Respond to smoke or other products of combustion

• Preferred over heat detectors

Firefighter II16–13

Smoke Alarms

• Capable of – Detecting presence of smoke– Sounding an alarm

Firefighter II16–14

Photoelectric Smoke Detectors

• Use photoelectric cell coupled with tiny light source

• Function in two ways to detect smoke

Firefighter II16–15

Ionization Smoke Detectors

• Detect minute particles, aerosols produced during combustion

• Use a tiny amount of radioactive material to ionize air molecules as they enter chamber within detector

(Continued)

Firefighter II16–16

Ionization Smoke Detectors

• Respond satisfactorily to most fires

• Respond faster to flaming fires than smoldering ones

Firefighter II16–17

Power Sources of Smoke Alarms

• Battery-operated• Household current

Firefighter II16–18

Flame Detectors

• Types• Among most sensitive detectors

used to detect fires• Prone to being activated by nonfire

conditions

(Continued)

Firefighter II16–19

Flame Detectors

• Usually positioned in areas where other light sources unlikely

• Positioned to have unobstructed view of protected area

(Continued)

Firefighter II16–20

Flame Detectors

• Some single-band IR detectors sensitive to sunlight, should be installed in fully enclosed areas

• UV detectors virtually insensitive to sunlight, can be used in areas not suitable for IR detectors

Firefighter II16–21

Fire-Gas Detectors

• Monitor levels of carbon dioxide, carbon monoxide because these are only chemicals released from all fires

• Initiate alarm signal faster than heat detector but not as quickly as smoke detector

(Continued)

Firefighter II16–22

Fire-Gas Detectors

• Can be more discriminating than other types

• Can be designed to be sensitive only to specific gases

(Continued)

Firefighter II16–23

Fire-Gas Detectors

• Use semiconductors/catalytic elements to sense gas, transmit signal to initiate alarm

• Not used as frequently as other types

Firefighter II16–24

Combination Detectors

Various combinations of previously described means of detection may be used in single device

Firefighter II16–25

Indicating Devices

• Some produce loud signal to attract attention in high-noise areas

• Some generate electronic tone audible in almost any type of environment

• Some employ bells, horns, chimes(Continued)

Firefighter II16–26

Indicating Devices

• Others use speakers that broadcast prerecorded evacuation instructions

• May include visual alarm indicators to accommodate special circumstances/populations

(Continued)

Firefighter II16–27

Indicating Devices

• May include strobe indicators — Must meet requirements of Americans with Disabilities Act in areas where there may be people with hearing impairments

Firefighter II16–28

Automatic Alarm Systems

• Transmit signal to off-site location to summon organized assistance

• Produce automatic response upon activation of local alarm

• May be installed to complement wet-pipe or dry-pipe sprinkler systems

Firefighter II16–29

Auxiliary Systems

• Local energy systems

• Shunt systems• Parallel telephone

systems

Firefighter II16–30

Remote Station Systems

• Similar to auxiliary systems but connected to fire department telecommunication center directly/through answering service by some means other than municipal fire alarm box system

(Continued)

Firefighter II16–31

Remote Station Systems

• Can be connected by leased telephone line or radio signal on dedicated frequency

• Common in localities not served by central station systems

(Continued)

Firefighter II16–32

Remote Station Systems

• May transmit coded or noncoded signal

• Must have ability to transmit trouble signal to fire alarm center when system impaired

(Continued)

Firefighter II16–33

Remote Station Systems

• May not have local alarm capabilities if evacuation is not desired action in fire

• May be monitored by entity besides fire department

Firefighter II16–34

Proprietary Systems

• Used to protect large commercial, industrial buildings, high-rise buildings, groups of commonly owned buildings in single location

(Continued)

Firefighter II16–35

Proprietary Systems

• Each building/area has own system wired into a common receiving point somewhere on facility

• The receiving station• Capabilities

Firefighter II16–36

Central Station Systems

• Very similar to proprietary systems; instead of having alarm-receiving point monitored by occupant’s representative on protected premises, receiving point is at off-site, contracted service point called a central station (Continued)

Firefighter II16–37

Central Station Systems

• Central station is alarm company that contracts with individual customers

(Continued)

Firefighter II16–38

Central Station Systems

• When alarm initiated at contracting occupancy, central station employees take information, initiate appropriate emergency response

• Response usually includes calling fire department, representatives of protected occupancy

(Continued)

Firefighter II16–39

Central Station Systems

• Alarm systems at protected property and central station most commonly connected by supervised telephone lines

Firefighter II16–40

Supervising Fire Alarm Systems

• Designed to be self-supervising• Older systems • Newer systems

(Continued)

Firefighter II16–41

Supervising Fire Alarm Systems

• Sounds of alarm, trouble signals may differ with each brand

• Many fixed fire suppression systems depend on signal from manual pull station/from automatic fire detection device to trigger suppression system

Firefighter II16–42

Auxiliary Services Available on Newer Systems

• Shutting down, altering airflow in heating, ventilating, and air-conditioning (HVAC) systems for smoke control

• Closing smoke/fire-rated doors, dampers

(Continued)

Firefighter II16–43

Auxiliary Services Available on Newer Systems

• Facilitating evacuation by increasing air pressure in stairwells to exclude smoke

• Overriding elevator controls• Monitoring operation of

commercial incinerator management systems

(Continued)

Firefighter II16–44

Auxiliary Services Available on Newer Systems

• Monitoring refrigeration systems, cold-storage areas

• Controlling personnel access to hazardous process/storage areas

• Detecting combustible/toxic gases

Firefighter II16–45

Principle Parts of Automatic Sprinkler System

• Water supply• Sprinkler valve• Alarm• Manual valve• System drain

(Continued)

Firefighter II16–46

Principle Parts of Automatic Sprinkler System

• Test connection• Sprinkler head• Riser• Feed main• Cross mains

Firefighter II16–47

Sprinklers

• Discharge water after release of cap or plug activated by some heat-responsive element such as fusible link

(Continued)

Firefighter II16–48

Sprinklers

• Identified by temperature at which designed to operate, either by color-coding, using different colored liquid, stamping temperature on sprinkler

(Continued)

Firefighter II16–49

Sprinklers

• Fusible link

• Frangible bulb

(Continued)

Firefighter II16–50

Sprinklers

• Chemical pellet

Firefighter II16–51

Sprinkler Position

• Pendant

• Upright

(Continued)

Firefighter II16–52

Sprinkler Position

• Sidewall• Special-purpose

Firefighter II16–53

Sprinkler Storage

• Storage cabinet to house spare sprinklers, a sprinkler wrench usually installed near sprinkler rise, main shut-off valve

• Cabinets hold a minimum of six sprinklers and sprinkler wrench in accordance with NFPA® 13 and 13D (Continued)

Firefighter II16–54

Sprinkler Storage

• In many jurisdictions, job of changing sprinklers must be performed by representatives of building’s occupants qualified to perform work on sprinkler systems

(Continued)

Firefighter II16–55

Sprinkler Storage

• In other jurisdictions, firefighters allowed to replace fused/damaged sprinklers to restore system to service sooner

Firefighter II16–56

Water Supply

• Minimum water supply has to deliver required volume of water to highest sprinkler in building at residual pressure of 15 psi (105 kPa)

• Minimum flow depends on hazard to be protected, occupancy, building contents (Continued)

Firefighter II16–57

Water Supply

• In most cases, water supply for sprinkler systems designed to supply only fraction of sprinklers actually installed on system

• If large fire occurs/pipe breaks, sprinkler system will need outside source of water and pressure

(Continued)

Firefighter II16–58

Water Supply

• Sprinkler FDCs should be supplied with water from pumpers that have capacity of at least 1,000 gpm (4 000 L/min) or greater; minimum of two 2½-inch (65 mm) or larger hoses should be attached to the FDC

(Continued)

Firefighter II16–59

Water Supply

• After water flows through FDC into system, passes through check valve

• Proper direction of water flow through check valve usually indicated by arrow on valve or appearance of valve casing

Firefighter II16–60

Water Supply

• Departmental preincident plans may identify the pressure at which a sprinkler system should be supported

Firefighter II16–61

Wet-Pipe Systems

• Used in locations where temperatures below 40°F (4°C) not expected

• Simplest type of automatic fire sprinkler system

(Continued)

Firefighter II16–62

Wet-Pipe Systems

• Generally require little maintenance

• Contain water under pressure at all times

• Connected to public/private water supply so fused sprinkler immediately discharges water spray, actuates alarm (Continued)

Firefighter II16–63

Wet-Pipe Systems

• Usually equipped with alarm check valve installed in main riser adjacent to where feed main enters building

• Newer versions may have a backflow prevention check valve and electronic flow alarm.

(Continued)

Firefighter II16–64

Wet-Pipe Systems

• May be equipped with retarding device as part of alarm check valve

Firefighter II16–65

Dry-Pipe Systems

• Used in locations where piping may be subjected to temperatures below 40°F (4°C)

(Continued)

Firefighter II16–66

Dry-Pipe Systems

• Have pitched (sloped) pipes to help drain water in system back toward main drain

• Replace water in sprinkler piping with air under pressure

(Continued)

Firefighter II16–67

Dry-Pipe Systems

• Designed so small amount of air pressure above dry-pipe valve will hold back much greater water pressure on water supply side of dry-pipe valve

• Equipped with electric or hydraulic alarm-signaling equipment

(Continued)

Firefighter II16–68

Dry-Pipe Systems

• Larger systems may have several-minute delay while air expelled from system

Firefighter II16–69

Preaction Systems

• Dry systems that employ deluge-type valve, fire detection device, closed sprinklers

• Used when especially important to prevent water damage, even if pipes broken

(Continued)

Firefighter II16–70

Preaction Systems

• Will not discharge water into sprinkler piping except in response to smoke- or heat-detection system actuation

• Sound alarm to give warning before opening of sprinklers

Firefighter II16–71

Deluge Systems

• Similar to dry-pipe system in no water in distribution piping before system activation

• Differ from dry-pipe systems in sprinklers have no fusible links, do not function as fire detection devices

(Continued)

Firefighter II16–72

Deluge Systems

• Designed to quickly supply large volume of water to protected area

• Sometimes used to discharge foam/other extinguishing agents in occupancies containing flammable liquids, other volatile fuels

Firefighter II16–73

Residential Systems

• Installed in one- and two-family dwellings

• Designed to give occupants of dwelling chance to escape, prevent total involvement in room of origin

• Employ quick-response sprinklers(Continued)

Firefighter II16–74

Residential Systems

• Use several types of piping systems

• Must have pressure gauge, flow detector, means for draining and testing system

• Can be either connected directly to public water supply or to dwelling’s domestic water system (Continued)

Firefighter II16–75

Residential Systems

• Require control valve to turn off water to sprinkler system and to domestic water system if connected; if sprinkler system supplied separately from domestic water system, sprinkler control valve must be supervised in open position (Continued)

Firefighter II16–76

Residential Systems

• Operate in same manner as other wet-pipe/dry-pipe systems

• May be equipped with fire department connection (FDC); FDC may be 1½-inch (38 mm) connection

Firefighter II16–77

Summary

• Many of the buildings to which firefighters are called for emergency operations are protected partially or fully by automatic fire detection and/or suppression systems.

(Continued)

Firefighter II16–78

Summary

• Firefighters need to familiarize themselves with the types of systems installed in their area of responsibility. They should also learn the locations of these systems as well as the capabilities and limitations of each type of system.

Firefighter II16–79

Review Questions

1.How does a photoelectric smoke detector work?2.How do flame detectors work?3.Describe the three basic types of auxiliary automatic alarm systems.

(Continued)

Firefighter II16–80

Review Questions

4. What is a proprietary automatic alarm system? 5.Describe commonly used release mechanisms to activate sprinklers.