Chapter 36 Fire Detection, Protection and Suppression Systems Flashcards
False Alarms
caused by malfunctions in system or placement, all alarms should be treated as true emergencies until proven otherwise.
Fire alarm components
- alarm initiation device
- alarm notification device
- fire alarm control panel
Alarm initiation device
either an automatic or manually operated device that when activated causes the system to indicate an alarm.
Alarm notification device
generally an audible device, often accompanied by a visual device, alerts the building occupants when the system is activated.
Fire alarm control panel
serves ast the brain of the system linking the activation devices to the notification devices
Remote annunciator
enable s fire fighters to ascertain the type and location of the activated alarm device as they enter the building.
Fire alarms are powered by?
110 volt line or lithium 10 year lithium battery
single station smoke alarm
most common type of residential
- safety detection device
- an automatic control unit
- audible alarm within a single unit
Ionization
detectors are triggered by the invisible products of combustion. Electrically charged microscopic particles.
Photoelectric
use a light beam and a photocell to detect larger visible particles of smoke. smoke prevents it from striking the photocell
Manual pull-station
such a station has a switch that either opens or closes an electrical circuit to activate the alarm.
Single-action pull stations
require a person to pull down a lever toggle or handle to activate the alarm. sounds as soon as the pull station is activated.
Double action pull stations
require a person to perform wot steps before the alarm will activate. Designed to eliminate false alarms
Tamper alarm
clear plastic covering sounds its own alarm when opened.
Smoke detector
designed to sense the presence of smoke.
commonly found is schools, hospitals business and commercial occupancies
Beam detector
a type of photoelectric smoke used protect large open areas
Obscuration rate
or percentage of light blocked
Heat Detectors
also commonly used automatic alarm initiation devices. provide property protection but cannot provide life-safety protection because they do not react quickly enough to incipient fires.
Spot Detectors
individual units that can be spaced throughout an occupancy, so that each detector covers a specific floor area. Light commercial residential settings
Fixed Temperature heat detectors
the name implies are designed to operate at a preset temperature
1. usually 135 degrees include metal
Rate-of-Rise Heat Detector
will activate if the temperature of the surrounding and rises more than a set amount in a given period of time. “greater than 12 degree in 1 minute”
Bimetallic strip
made of two metals that respond differently to heat: raid causes the strip to bend unevenly which opens and closes switch. also air chamber/diaphragm mechanism. increase in heat increase in pressure activates
Line Detectors
use wire or tubing strung along the ceiling of large opens areas to detect increase in heat
Flame Detectors
specialized devices rare and expensive. they detect electric magnetic light waves produced by flames (air craft carriers)
Gas Detectors
calibrated to detect the presence of a specific gas that is created by combustion or that is used in the facility. Commercial or industrial applications
Air Sampling detectors
continuously capture air samples and measure the concentrations of specific gases or product of combustion.
Automatic sprinkler systems
usually connected to the fire alarm system, will activate the alarm if a water flow occurs.
Malicious False Alarms
when individuals deliberately activate a fire alarm when there is no fire and causes a disturbance.
Unwanted alarms
occurs when an alarm system is activated by a condition that is not really an emergency.
Nuisance Alarms
caused by improper functioning of an alarm system or one of its components
Cross-zoned system
activation of a single smoke detector will not sound the fire alarm
Verification system
there is a delay of 30 to 60 second between activation and notification. (pre alarm before full alarm)
temporal 3 pattern tone
produced by audio device usually with a visual aid for the hearing impaired and blind.
Categories of alarm annunciation systems
noncoded alarm, zoned noncoded alarm, zoned coded alarm, master-coded alarm
noncoded alarm
no info is given on what the device was activated or where it is located.
zoned non coded alarm
control panel indicates the zone in the building that was the source of the alarm. it may also indicate the specific device that was activated.
zoned coded alarm
indicates over the audible warning device which zone has been activated. usually used in hospitals where it is not feasible to evacuate the entire facility.
Master-coded alarm
system is zoned and coded. audible warning devices are also used for other emergency related functions.
local alarm system
does not notify fire dept. occupants must call FD
remote station system
sends signal to fire department.
auxiliary systems
be used in jurisdictions with a public fire alarm box system.
Fire gong
activated by moving water
Proprietary system
building fire alarms are connected directly to a monitoring site that is owned and operated by the building owner. central control panel
central station
third party (ADT) off site monitoring facility that monitors multiple alarm systems.
Basic components of an automatic sprinkler system
sprinkler heads, piping, control valve, and water supply
Automatic sprinkler heads components (3)
- 1/2 inch orifice
- deflector
- release mechanism
Fusible-link sprinkler heads
use metal alloys that melt at certain temps
Frangible bulb sprinkler heads
a glass bulb filled with glycerin or alcohol to hold the cap in place
Chemical pellet sprinkler heads
use a plunger mechanism and a small chemical pellet to hold the cap in place.
Early suppression fast response sprinklers
have improved heat collectors that speed up the response and ensure rapid release of water.
Deluge heads
easily identifiable, they no cap or release mechanism. temp is usually 165 for sprinkler systems.
Mounting positions for sprinklers
- Pendant sprinkler heads- designed to be mounted on the underside of the sprinkler piping hanging down.
- Upright sprinkler heads- designed to be mounted on tope of the supply piping
- Side wall- horizontal mounting projecting out from a wall.
Valves
- OS&Y
2. PIV
OS&Y
has a stem that moves in and out as the valve is opened or closed. mostly inside Found outside in warmer climates
PIV
reads OPEN or CLOSED (SHUT) found outside
Tamper switches
these devices monitor the position of the valve. sends signal to fire alarm control panel
water sources
- municipal
2. FD supported
FDC (fire department connections)
two or more 2 1/2 inch female couplings allows FD to connect and provide water.
Types of automatic sprinkler systems
- wet sprinkler systems
- dry sprinkler systems
- preaction sprinkler systems
- deluge sprinkler systems
Wet sprinkler systems
most common and least expensive type. always filled with water. cant be used in below freezing and can cause leaks
Dry sprinkler systems
pipes are filled with pressurized air instead of water.
Accelerator
installed at the dry pipe valve when pressure drops it is activated
Pre action sprinkler system
a secondary device such as a smoke detector or a manual pull alarm must be activated before water is released into the sprinkler piping.
deluge sprinkler system
is a type of dry sprinkler system in which water flows from all of the sprinkler heads as soon as the system is activated.
Shutting down sprinkler systems
systems are shut down by IC after fire extinguishers.
Standpipe system
Class1, class 2, class 3
Class !
designed for FD personnel only
Class 2
is designed for use by the building occupants. 1 1/2 single jacket hose pre connected to the system
Class 3
features both class 1 and 2 in a single system.
Specialized ext. systems Dry chemical
kept in self pressurized tanks or in tank with an external cartridge of carbon dioxide or nitrogen that provides pressure when the system is activated.
Wet Chemical
used in most new commercial kitchens
Clean Agent
Halon and CO2 give pre alarm 30-60 sec.
