Transcript Refresher - Ventilation Basics

Refresher - Ventilation Basics
Brantley County Fire Departments
Monthly Training
Conducted by the Atkinson Volunteer
Fire Department
July 2008
Welcome
• Introductions
• Housekeeping
July, 2008
Atkinson Volunteer Fire Department
2
Terminal Objective
The student will demonstrate the principles
of ventilation, a basic understanding of
building construction, the safety precautions
to be taken when ventilating a structure, and
how to use the various types of ventilation
through classroom participation and
discussion.
July, 2008
Atkinson Volunteer Fire Department
3
Enabling Objectives
• Discuss principles of ventilation
• Identify the 5 classifications of building
construction
• Identify several different roofing styles
• Identify safety precautions that should be
taken when undertaking ventilation
operations
July, 2008
Atkinson Volunteer Fire Department
4
Enabling Objectives
• Discuss different methods of conducting
ventilation
• Discuss techniques for ventilating different
structure types and roof styles
July, 2008
Atkinson Volunteer Fire Department
5
Principles of Ventilation
What is Ventilation?
The planned, methodical, and systematic
removal of pressure, heat, smoke, toxic
gases, and flame from an area through
predetermined paths and the replacement of
these products with cooler fresh air
July, 2008
Principles of Ventilation
7
How does it work?
• Heat and smoke rise
• Path of least resistance
• Smoke moves horizontally and vertically –
mushrooming
July, 2008
Principles of Ventilation
8
Why do we ventilate?
•
•
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•
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Removal of smoke, heat, and fire gases
Improve visibility
Reduce potential harm to victims
Reduce stress on firefighters
Assist with fire control and extinguishment
July, 2008
Principles of Ventilation
9
Advantages
• Increased visibility
– See the victim
– Find the seat of the fire
• Increased effectiveness of fire attack
• Reduced possibility of flashover or
backdraft
• Aids in property conservation
– Small amount of ventilation damage results in
larger reduction in overall fire damage
July, 2008
Principles of Ventilation
10
Results Depend On
• Size and type of occupancy
• Extent and location of fire
• Whether fire is free-burning or smoldering
July, 2008
Principles of Ventilation
11
Ventilation Concerns
• Fire travel by convection – greatest
firefighting problem
– May cause exposure fires and additional fires
in fire structure
• Improper ventilation may increase fire
spread
July, 2008
Principles of Ventilation
12
General Rule
To open the fire building so that all
accumulations of heat and combustion
products leave by means of natural
convection
July, 2008
Principles of Ventilation
13
Building Construction
5 Classifications
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Type I – Fire Resistive
Type II – Noncombustible
Type III – Ordinary
Type IV – Heavy Timber
Type V – Wood Frame
July, 2008
Building Construction
15
Type I – Fire Resistive
• Made of noncombustible materials
• Structural elements subject to damage by
heat must be protected by noncombustible
coverings
• 2 to 4 hour fire resistance rating
• Shopping malls, office buildings, etc…
July, 2008
Building Construction
16
Type II - Noncombustible
• Made of noncombustible materials
• Structural elements subject to damage by
heat generally not protected by
noncombustible coverings
• 0 to 2 hour fire resistance rating
• Warehouses, repair shops, etc…
July, 2008
Building Construction
17
Type III - Ordinary
• Exterior walls made of noncombustible
materials
• Interior walls generally made of wood
• 0 to 1 hour fire resistance rating
• “Main Street USA”
July, 2008
Building Construction
18
Type IV - Heavy Timber
• Exterior walls made of noncombustible
materials
• Interior structural members made of heavy
timbers
• Mills
July, 2008
Building Construction
19
Type V – Wood Frame
• Made of combustible materials
• May have up to 1 hour fire resistance
rating
• Residential structures
• Most Type V structures built today use
lightweight construction methods
July, 2008
Building Construction
20
Roof Styles
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Hipped
Gable
Gambrel
Saltbox
July, 2008
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•
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•
Mansard
Flat
Shed
Arched
Building Construction
21
Hipped Roof - Simple
• All four sloping
sides meet at a
ridge across the
top. Front slope
is usually
broader than the
side sections
July, 2008
Building Construction
22
Hipped Roof - Pyramidal
• All four sloping
sides come to a
point at the top
of the roof
July, 2008
Building Construction
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Gable
• Two flat slopes that
are joined together to
form a ridge, thus
creating a peak or
triangle on the wall of
the front façade
July, 2008
Building Construction
24
Gambrel
• Each side has two
slopes; a steeper
lower slope and a
flatter upper one;
associated with barns
July, 2008
Building Construction
25
Flat
• Contains no slope.
May or may not have
eaves
July, 2008
Building Construction
26
Saltbox
• A gabled roof with
asymmetrical sides. It
is said to resemble an
eighteenth century
salt box
July, 2008
Building Construction
27
Mansard
• A roof forming a
double slope, two
slopes on each of the
four sides. The lower
slope being steeper
than the other
July, 2008
Building Construction
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Shed
• One high pitched
plane covering the
entire structure.
Often used for
additions and
porches
July, 2008
Building Construction
29
Arched
• Roof that curves from
wall to wall, may go
completely from
ground to ground.
Used in aircraft
hangers, bowling
alleys, and older
grocery stores
July, 2008
Building Construction
30
Roof Construction
• Rafter and beam
• Lightweight wooden truss
• Steel truss
July, 2008
Building Construction
31
Lightweight Wood Truss
• Engineered with lumber sized smaller than
traditional dimensional lumber
• Accounts for over 60% of all new construction
• Very short life expectancy when exposed to fire
July, 2008
Building Construction
32
Lightweight Wood Truss
• Held together with
gusset plates
instead of nails
July, 2008
Building Construction
33
Safety Precautions
Safety Precautions
• Always wear full PPE, to include SCBA
• Always vent at highest point possible
• Have hoselines in place to make interior
attack
• Work with wind at back or side
• Never flow water into vent hole with
personnel inside building
• Check roof stability before starting
operations
July, 2008
Safety Precautions
35
Safety Precautions
• Restrict number of personnel to minimum
needed to accomplish task
• Work from roof ladder when cutting hole
• Watch out for overhead power lines
• Have secondary escape routes in place
• Check equipment before going on roof
• Do not cut main structural supports
July, 2008
Safety Precautions
36
Safety Precautions
• Watch out for unsafe or deteriorating
conditions
• Note and avoid any existing dead loads or
obstructions
• Maintain communications
• Remove crew from roof when vent
operations concluded
July, 2008
Safety Precautions
37
Lightweight Construction
• Notify IC when lightweight truss
construction found
• Avoid working around areas with roof
mounted equipment
• Always expect imminent collapse when
lightweight truss construction is being
impinged by fire
• Work off of aerial ladders where possible
July, 2008
Safety Precautions
38
Backdraft
Sudden violent reignition of a closed
compartment fire when a new source of
oxygen is introduced
July, 2008
Safety Precautions
39
Backdraft Signs
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Smoke visible, but no flames
Yellowish colored smoke
Windows darkened over
Smoke puffing from openings (breathing
building)
• Smoke under pressure
July, 2008
Safety Precautions
40
Rollover
Smoke and fire gases advancing along a
ceiling until stopped by walls
July, 2008
Safety Precautions
41
Flashover
• The sudden rapid ignition of all contents of
a room or area
• Seconds to escape
July, 2008
Safety Precautions
42
Flashover Signs
• Rollover progressing close to floor
• Large amounts of flame and heat with little
smoke
• Tunnel Effect
July, 2008
Safety Precautions
43
What Can Go Wrong
• Fatality
– September 14, 2002
• A firefighter died after falling through roof while
observing another firefighter conducting ventilation
operations. The deceased firefighter was not
wearing SCBA.
– Source – NIOSH Fatality Assessment and Control
Evaluation Investigation Report 2002-40
July, 2008
Safety Precautions
44
What Can Go Wrong
• Near Miss
– March 1, 2003
• Firefighters were conducting search operations in
low attic when one firefighter felt a jerk to his
helmet. The firefighter immediately dropped to the
floor and the interior crew exited the building.
Observation of struck firefighter’s helmet revealed
where chainsaw from vent operations struck him.
– Source – National Firefighter Near Miss Reporting
System Report 05-0000339
July, 2008
Safety Precautions
45
What Can Go Wrong
• Near Miss
– January 13, 2007
• Firefighters were conducting trench ventilation
operations on a church made from lightweight
truss construction. Personnel were operating from
an aerial ladder when 40 feet of roof collapsed,
sending a 30 foot fireball into the sky.
– Source – National Firefighter Near Miss Reporting
System Report 07-0000726
July, 2008
Safety Precautions
46
What Can Go Wrong
• Near Miss
– December 19, 2005
• Firefighters were conducting vent operations on an
ice covered roof and were having trouble getting
back to their ladders. Personnel from a
neighboring department were able to move an
aerial ladder to the crew to aid in exiting roof.
– Source – National Firefighter Near Miss Reporting
System Report 07-0000854
July, 2008
Safety Precautions
47
What Can Go Wrong
• Near Miss
– December 7, 2007
• Firefighters were conducting training on ventilation
operations when the chain and chain guide came
off chainsaw.
– Source – National Firefighter Near Miss Reporting
System Report 07-0001157
July, 2008
Safety Precautions
48
Ventilation Methods
Direction of Travel
• Horizontal
• Vertical
July, 2008
Ventilation Methods
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Horizontal Ventilation
• Uses natural
openings in
occupancy
• Doors and windows
• Effective in
basements and high
rise structures
July, 2008
Ventilation Methods
51
Horizontal Ventilation
• Technique
– Open leeward side openings first, highest
point possible
– Open windward side openings next, lowest
point
– Coordinate openings used with Command
– Select openings used with future ventilation
operations in mind
July, 2008
Ventilation Methods
52
Horizontal Ventilation
• Advantages
– Quick to deploy
– Minimal effort to conduct
– Relatively Safe
July, 2008
Ventilation Methods
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Horizontal Ventilation
• Disadvantages
– Limited to natural openings
– Access to openings may be hindered
– Does not use natural flow of heat and smoke
– May change dynamics of fire attack
– May cause increase in fire spread
– Can be affected by prevailing weather
conditions
July, 2008
Ventilation Methods
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Vertical Ventilation
• Considered most
effective avenue to
exhaust smoke and
fire gases
• Openings made
above fire
• Highest point closest
to fire
July, 2008
Ventilation Methods
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Vertical Ventilation
• Technique
– Utilize existing openings first
– Consider using stairwells and shafts
– When creating opening, make one large
opening rather than several small openings
– Get off roof when completed
July, 2008
Ventilation Methods
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Vertical Ventilation
• Advantages
– Allows heat and smoke to follow natural
movement pattern
– Best for reducing potential for backdraft
– Can assist in localizing fire due to ventilation
hole placement
July, 2008
Ventilation Methods
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Vertical Ventilation
• Disadvantages
– Time Consuming
– Inherently dangerous
– Equipment malfunctions
– Building construction
July, 2008
Ventilation Methods
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Ventilation Methods
• Natural
• Mechanical
• Hydraulic
July, 2008
Ventilation Methods
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Natural Ventilation
• Uses existing air flow and convection
currents
• Openings may be existing or created
• Horizontal or Vertical
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Negative pressure
• Positive pressure
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Negative Pressure
– Pulling smoke and fire
gases out of
occupancy through
use of a vacuum
condition
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Negative Pressure – Technique
– Horizontal ventilation style
– Fan Placement
– Supplements other ventilation methods
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Negative Pressure – Advantages
– Effective when other methods are not
– Helps maintain positive control of operations
– Supplements other ventilation directions and
methods
– Can be faster than natural ventilation
– Applicable to all types of structures
– Reduces churning of air in structure
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Negative Pressure – Disadvantages
– May cause fire to spread and intensify
– Needs external power source
– Can interfere with ingress and egress to
structure
– Requires firefighter to stand during placement
– Requires opening to be sealed around fan
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Positive Pressure
– Pushing smoke and
gases out by creating
an overpressure
condition inside
occupancy
– Considered the current
method of choice for
horizontal ventilation
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Positive Pressure – Technique
– Horizontal ventilation style
– Fan Placement
– Exhaust opening near seat of fire
– Close off areas not to be vented
– Most effective when doors and windows still
intact
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Positive Pressure - Advantages
– Method of choice
– Does not interfere with ingress or egress
– Quick set-up
– Does not require entry into occupancy
– Does not require explosion proof fans
– Does not require gases to pass through fan
July, 2008
Ventilation Methods
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Mechanical Ventilation
• Positive Pressure – Disadvantages
– Requires special equipment
– May cause fire spread
– Noise
– Must have preexisting air flow path
July, 2008
Ventilation Methods
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Hydraulic Ventilation
• Utilizes Venturi
Principle to create
vacuum which pulls
smoke and fire gases
out of occupancy
July, 2008
Ventilation Methods
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Hydraulic Ventilation
• Technique
– 30 degree fog pattern on nozzle
– Cover at least 85% of window
– Leave window corners open
– Nozzle should be at least 2 feet from window
July, 2008
Ventilation Methods
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Hydraulic Ventilation
• Advantages
– Rapid to deploy
– Minimal equipment requirements
– Effective in any occupancy type
July, 2008
Ventilation Methods
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Hydraulic Ventilation
• Disadvantages
– Water Usage
– Water Damage
July, 2008
Ventilation Methods
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Ventilation Techniques
Horizontal Ventilation
• Step 1
– Position yourself
to the side of the
opening selected
to be removed
July, 2008
Ventilation Techniques
75
Horizontal Ventilation
• Step 2
– Maintain control
of tool and break
window at highest
point reachable
July, 2008
Ventilation Techniques
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Horizontal Ventilation
• Step 3
– Remove rest of
glass in window
July, 2008
Ventilation Techniques
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Horizontal Ventilation
July, 2008
Ventilation Techniques
78
Mechanical Ventilation
• Negative Pressure
– Secure fan at top of
opening
– Seal rest of opening
– Remove all drapes,
shades, etc… from
around opening
– Check direction of
exhaust before
starting
July, 2008
Ventilation Techniques
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Mechanical Ventilation
• Positive Pressure – Single Fan
– Ensure fan is ready for operation prior to
placement at opening
– Have fan at ventilation point running at idle
– When called for, increase speed of fan
– Position fan 6 to 10 feet from opening
– Ensure discharge opening is smaller than fan
opening
July, 2008
Ventilation Techniques
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Mechanical Ventilation
• Positive Pressure – Single fan
July, 2008
Ventilation Techniques
81
Mechanical Ventilation
• Positive Pressure – Multiple Fans
– Fans Side by Side
• Double Doors
• Large Windows
• 6 to 10 feet from opening
– Fans Stacked
• First fan 3 to 5 feet from opening
• Second fan 6 to 10 feet from opening
July, 2008
Ventilation Techniques
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Mechanical Ventilation
• Positive Pressure – Multiple Fans stacked
July, 2008
Ventilation Techniques
83
Vertical Ventilation
• Pre-existing openings
• Created openings
July, 2008
Ventilation Techniques
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Vertical Ventilation
• Pre-existing openings
– Skylights
– Stairwell or Elevator shafts
– Scuttle hatches
– Attic vents
July, 2008
Ventilation Techniques
85
Vertical Ventilation
• Tools Needed
– Pike pole, 6 foot minimum
– Pick head axe
– Power saw
• Chainsaw with depth gauge
• Rotary saw
– Ladders
– Charged hoseline
July, 2008
Ventilation Techniques
86
Vertical Ventilation
• General Procedure
– Determine where to ventilate
• As close to fire as possible
• Highest point possible
– Extend ladder 3 to 5 rungs above roof edge
– Sound roof
– Deploy roof ladder
– Sound to determine roof supports
July, 2008
Ventilation Techniques
87
Vertical Ventilation
• General Procedure – con’t
– Mark out location for opening
– Remove roofing material (shingles, etc…)
– Cut opening, 4x4 feet in size
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Furthest cut
Top cut
Bottom cut
Closest cut
– Pry up cut material
July, 2008
Ventilation Techniques
88
Vertical Ventilation
• General Procedure – con’t
– Inform Command when ready to open ceiling
below opening
– Open ceiling when ordered to
– EXIT ROOF when done
July, 2008
Ventilation Techniques
89
Vertical Ventilation
• Safety concerns
– WEAR ALL PPE
– Ensure roof stability BEFORE getting on roof
– 2 means of egress from roof
– Minimum personnel needed
– DO NOT flow water into opening
– Notify Command if lightweight truss
construction discovered
July, 2008
Ventilation Techniques
90
Vertical Ventilation
• Safety concerns – con’t
– Work with wind at back or side
– Use ladders or other means to keep from
sliding off roof
– Be aware of electrical lines and antennas
– Do not carry running power tools up ladder
July, 2008
Ventilation Techniques
91
Trench Ventilation
• Defensive
tactic used to
stop fire
spread
• Very labor
intensive
• Cut is 4 feet
wide going
from roof edge
to roof edge
July, 2008
Ventilation Techniques
92
Ventilation Specifics
1 or 2 Family Dwelling
• Numerous roof styles and designs
• Most new houses are lightweight
construction
• May have basements
• Can be multiple stories
• May or may not have sprinklers
July, 2008
Ventilation Specifics
94
1 or 2 Family Dwelling
• General method of choice
– Horizontal (Natural/Mechanical)
• Basement fires
– Consider cutting first floor over fire and near
window
– Vent basement with PPV from exterior
basement entrance
July, 2008
Ventilation Specifics
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1 or 2 Family Dwelling
• Attic Fires
– Verify type of construction if possible
– Attack from below if safe to do so
– Horizontally vent using gable vents or attic
vents
• Pull vents from aerial if possible
July, 2008
Ventilation Specifics
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1 or 2 Family Dwelling
• Vent while making entry
• Coordinate with Command concerning
openings to ventilate
• Open only where necessary when
necessary
July, 2008
Ventilation Specifics
97
Multiple Family Dwelling
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Multiple construction methods
Multiple roof styles
Multiple stories
Larger fire load
May be sprinklered
Lightweight construction becoming more
prevalent
July, 2008
Ventilation Specifics
98
Multiple Family Dwelling
• General method of choice
– Dependent on construction type
– Dependent on fire floor
• Horizontal for lower floors
• Vertical for upper floors
July, 2008
Ventilation Specifics
99
Multiple Family Dwelling
• Open cockloft fire
– Open existing openings first
– Consider trench cut to stop fire movement
July, 2008
Ventilation Specifics
100
Commercial Building
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Come in all shapes and sizes
Can fall into any construction classification
Generally large square footage
Most have flat roofs
May or may not be sprinklered
Generally have multiple stories
July, 2008
Ventilation Specifics
101
Commercial Building
• Be aware of
– Dead loads on roof
– Unprotected structural members
– Lightweight construction methods
– Concrete roofs
July, 2008
Ventilation Specifics
102
Commercial Building
• Ventilation method will depend on fire
location and construction classification
• When venting roof
– Use existing openings first
• Skylights
• Elevator shafts
• Stairwells
• Preplan
July, 2008
Ventilation Specifics
103
Shopping Centers
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Assume no fire stop in place
Avoid spongy or sagging sections of roof
Use existing openings first
Be aware of roof attachments and
overhangs
• As last resort cut roof openings
July, 2008
Ventilation Specifics
104
Fire Resistive Structures
• Windows are opening of choice
• Building may have fire pressurization or
smoke removal system in place
• Preplan
July, 2008
Ventilation Specifics
105
Size Up
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Which ventilation method will work best
Are resources available
What are fire conditions
Where is the fire
Is roof stable enough
How long will it last
July, 2008
Ventilation Specifics
106
Pitched Roofs
• Can go from very shallow to very steep
• Generally covered with asphalt shingles
– May also have wooden shakes, metal sheets,
or clay or ceramic tile
• Most common pitch roof style is gable
• Most newer structures are constructed of
lightweight construction
July, 2008
Ventilation Specifics
107
Pitched Roofs
• Use roof ladder regardless of pitch
– Use aerial if pitch too steep
• Tool of choice
– Chainsaw
• Full PPE
July, 2008
Ventilation Specifics
108
Mansard Roof
• Variable pitch
– Traditional Mansard has 2 angles
– Modern Mansard has steep side and flat
center
• Generally covered with shingles on angles
and tar and gravel on flat portions
• Large open voids under roof
• Work off aerial if roof ventilation is needed
July, 2008
Ventilation Specifics
109
Flat Roof
• Generally seen in multi occupancy type
structures
• Often have large dead loads
• Tar and Gravel over Concrete
• Use existing openings rather than cut new
ones
• Preplan
July, 2008
Ventilation Specifics
110
Problems
• Steel Plating
– Placed over existing roof openings
– May cover entire roof
• Covered Windows
– Steel grating
– Masonry block
• Roll up security gates
July, 2008
Ventilation Specifics
111
Questions???