Transcript CVFD Training – Ventilation Practices

CVFD Training – Ventilation
Practices
SFFMA Training Objectives:
8-01.01 – 8-01.04
Life Safety Reasons for Fireground
Ventilation
• Increases firefighter safety by reducing interior
temperature, increasing visibility
• Reduces chance of firefighters receiving steam
burns when water applied
(Continued)
Firefighter I
11–2
Life Safety Reasons for Fireground
Ventilation
• Reduces likelihood of sudden, hazardous
changes in fire behavior
• Simplifies, expedites search and rescue
operations by removing smoke, gases that
endanger trapped/unconscious occupants
Firefighter I
11–3
Fire Attack and Extinguishment Reasons for
Fireground Ventilation
• Permits firefighters to more rapidly locate fire,
proceed with extinguishment
• When ventilation opening made in upper
portion of building, chimney effect occurs
(Continued)
Firefighter I
11–4
Fire Attack and Extinguishment Reasons for
Fireground Ventilation
Firefighter I
11–5
Fire Spread Control Reasons for
Fireground Ventilation
• Effective ventilation
– Reduces rate of smoke layer development
– Can reverse process of smoke layer development
– Reduces rate at which fire will spread over area
(Continued)
Firefighter I
11–6
Fire Spread Control Reasons for
Fireground Ventilation
• Even with proper ventilation, if fire not
extinguished soon after ventilation completed,
increased supply of fresh air will feed fire
• Ventilation should occur only after hoseline
crews ready to move in, attack
(Continued)
Firefighter I
11–7
Fire Spread Control Reasons for
Fireground Ventilation
Firefighter I
11–8
Reduction of Flashover Potential Reasons for
Fireground Ventilation
• Flashover
– Transition between growth, fully developed
– As unventilated interior fire burns and flames,
smoke, and gases extend, heat radiates back down
until combustibles heated to ignition
temperatures
– Once ignition temperatures reached, contents will
ignite
(Continued)
Firefighter I
11–9
Reduction of Flashover Potential Reasons for
Fireground Ventilation
• Ventilation helps prevent flashover from
occurring
• Opening single door or window may not
remove enough smoke, heat to prevent
flashover
(Continued)
Firefighter I
11–10
Reduction of Flashover Potential Reasons for
Fireground Ventilation
• If fire producing significant amount of smoke
and heat but limited by available oxygen,
ventilating room may cause rapid ignition of
hot fire gases in upper layer, initiating
flashover
Firefighter I
11–11
Reduction of Backdraft Potential Reasons for
Fireground Ventilation
• When fire confined in compartment and does
not break window or burn through to outside,
will reduce oxygen level until flaming
combustion no longer possible
• If air supply introduced, backdraft occurs
(Continued)
Firefighter I
11–12
Reduction of Backdraft Potential Reasons for
Fireground Ventilation
To prevent backdraft conditions, carefully controlled ventilation must be
provided
Vertical ventilation often safest for this
Signs of potential backdraft
Firefighter I
11–13
DISCUSSION QUESTION
Do you know of any examples of fires in which
backdraft occurred?
Firefighter I
11–14
Property Conservation Reasons for
Fireground Ventilation
• Rapid extinguishment reduces
water, heat, smoke damage
• Timely, effective ventilation
helps extinguish interior fires
faster
• Smoke may be removed from
buildings by natural or
mechanical means
(Continued)
Firefighter I
11–15
Property Conservation Reasons for
Fireground Ventilation
• When smoke, gases, heat removed from
burning building, fire can be confined
• If sufficient personnel, effective salvage
operations can be initiated outside immediate
fire area during fire control operations
Firefighter I
11–16
Considerations Affecting Ventilation
•
•
•
•
Is there need at this time?
Where is ventilation needed?
What type should be used?
Do fire, structural conditions allow for safe
roof operations?
• Are Vent Group personnel trained, equipped
to ventilate building?
Firefighter I
11–17
Life Safety Hazards
• First consideration is safety of firefighters and
building occupants
• Life hazards in burning building generally
lower if occupants awake
• If occupants asleep, a number of possibilities
must be considered
(Continued)
Firefighter I
11–18
DISCUSSION QUESTION
What are some ways to determine if there are
occupants still inside the building?
Firefighter I
11–19
Life Safety Hazards
• Depending on fire conditions, ventilation may
be needed before search and rescue begins
• Hazards from accumulation of smoke, gases in
building
Firefighter I
11–20
Visible Smoke Conditions
• Smoke accompanies most
ordinary forms of combustion
• Density of smoke increases
with amount of suspended
particles
• Smoke conditions vary
according to how burning has
progressed
Firefighter I
11–21
The Building Involved
• In addition to location of fire within building,
building’s age, type, design must be
considered
• Other factors include number and size of wall
openings, type of roof construction, etc.
(Continued)
Firefighter I
11–22
The Building Involved
• If results of preincident planning have been
documented and are available to officers on
fireground, may provide valuable information
affecting ventilation
(Continued)
Firefighter I
11–23
The Building Involved
• High-rise buildings
have extra
considerations
Firefighter I
11–24
Basements and Windowless Buildings
• Without effective ventilation, access into
basement is difficult because firefighters must
descend through worst heat, smoke to get to
seat
• Several features impede attempts at natural
ventilation
(Continued)
Firefighter I
11–25
Basements and Windowless Buildings
• Many buildings have windowless wall areas
• In some cases, creating openings needed may
delay operation considerably
• Ventilating considerations
(Continued)
Firefighter I
11–26
Basements and Windowless Buildings
Firefighter I
11–27
Location and Extent of Fire
• First-arriving units must determine size, extent
of fire as well as location
• Severity, extent of fire depend on number of
factors
(Continued)
Firefighter I
11–28
Location and Extent of Fire
• Phase to which fire has progressed is a
primary consideration in selecting ventilation
procedures
• Ways that vertical fire extension occurs
Firefighter I
11–29
Selecting Place to Ventilate
• Ideal situation one with as much information
as possible about fire, building, occupancy
• Many factors have bearing on where to
ventilate
(Continued)
Firefighter I
11–30
Selecting Place to Ventilate
• Many considerations before ventilating
building
Firefighter I
11–31
Horizontal Ventilation
• Venting of heat, smoke, and gases through
horizontal openings
• Certain structures lend themselves to this
application
(Continued)
Firefighter I
11–32
Horizontal Ventilation
• Many aspects of vertical ventilation apply to
horizontal ventilation; different procedure
must be followed
• Besides direct flame contact, horizontal
extension can occur in several ways
Firefighter I
11–33
Horizontal Ventilation Considerations
— Weather
• Must always be
considered
• Wind has most
potential influence;
can aid or hinder horizontal ventilation
• Wind direction
• Setting up natural horizontal ventilation
Firefighter I
11–34
DISCUSSION QUESTION
What are some other weather conditions that
should be considered before performing
horizontal ventilation?
Firefighter I
11–35
Horizontal Ventilation
Considerations — Exposures
• Internal — Include building occupants, any
uninvolved rooms/portions of building
• External
(Continued)
Firefighter I
11–36
Horizontal Ventilation
Considerations — Exposures
• Because horizontal ventilation does not
release heat and smoke directly above fire
– Routing necessary
– Routes may be same needed for evacuation
– Effects on rescue, exit must be considered
(Continued)
Firefighter I
11–37
Horizontal Ventilation
Considerations — Exposures
• Because heat, smoke, fire can
be discharged below highest
point of building
– Also danger that rising gases
will ignite portions of building above exit point
– Rising gases may be drawn into windows/
attic vents above exit point
(Continued)
Firefighter I
11–38
Horizontal Ventilation
Considerations — Exposures
• Because heat, smoke, fire can be discharged below
highest point of building (cont.)
– They may ignite eaves of building/adjacent structures
– Unless for rescue, building should NOT be ventilated until
charged hoselines in place at entry point
– Charged hoselines should be ready at intermediate point
where fire might spread
(Continued)
Firefighter I
11–39
Daylight Basement Ventilation
Considerations
• Daylight basements
– Occur in homes built on slopes
– Finished basements with large exterior windows,
possibly exterior door(s)
– Easier to ventilate than conventional
• Opening door, breaking windows, etc.
provides adequate ventilation
Firefighter I
11–40
Precautions Against Upsetting
Horizontal Ventilation
• Opening a door/window on windward side of
building prior to ventilation exit opening on
leeward size may pressurize building, intensify
fire, cause fire spread
(Continued)
Firefighter I
11–41
Precautions Against Upsetting
Horizontal Ventilation
• Take advantage of air currents
• If established currents blocked, positive
effects may be reduced/eliminated
Firefighter I
11–42
Advantages of Forced Ventilation
•
•
•
•
•
Supplements, enhances natural ventilation
Ensures more control of air flow
Speeds removal of contaminants
Reduces smoke damage
Promotes good public relations
Firefighter I
11–43