Objectives
1 of 3
Understand ventilation as a fire service
tool.
 Know the principles, advantages, and
effects of ventilation.
 Know the origins and effects of heat,
smoke, and toxic gases.
 Differentiate between flashover, backdraft,
and rollover.

Objectives
3 of 3
Identify safety considerations when
venting operations are in progress.
 Identify the factors affecting ventilation.
 Describe ventilation techniques.
 Identify the types of ventilation.
 Identify the mechanics of ventilation.

Introduction
Ventilation is the planned and systematic
removal of pressure, heat, gases, and smoke.
 Ventilation is a very complex subject area with
many factors.
 Ventilation is a part of the coordinated fire

attack.

Ventilation will be in place before fire attack!!
Principles, Advantages, and
Effect of Ventilation
1 of 3
Ventilation is the relief of the products of
combustion from an enclosed area.
 This is a very essential part of fire
suppression effort.
 This prevents fire from heating up other
parts of the structure.

Principles, Advantages, and
Effect of Ventilation
2 of 3
As heat is exhausted and dissipated its
ability to spread the fire is reduced
 Ventilation channels smoke out of the
structure.
 As smoke builds up vision is obscured.
 Heavy smoke conditions can obscure light
completely.

Principles, Advantages, and
Effect of Ventilation
3 of 3
Unburned hydrocarbons irritate eyes.
 Smokes contain many deadly
substances.
 Removal of smoke will add survival time
to a victim, increasing the chance of
successful rescue.

Heat, Smoke, and Toxic Gases
When fire burns, air heats, expands,
becomes lighter, and rises.
 Heated air spreads by convection and
radiation.
 Fire gases consists of many deadly
products of combustion.
 Newer approach to construction makes
ventilation even more important.

Considerations for Proper
Ventilation
1 of 3
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Important to understand behavior of fire
gases.
Smoke rises and mushrooms.
Vertical ventilation is the removal of gases and
smoke through vertical channels.
Horizontal ventilation is channel smoke through
horizontal openings.
Without ventilation, heat, smoke and steam
have no where to go.
Path of Travel for Smoke
Considerations for Proper
Ventilation
2 of 3
An opening is needed for smoke and byproducts to exit as attack team moves in.
 Ventilation can be as critical as applying
water.
 Many factors must be considered when
venting.

Considerations for Proper
Ventilation
3 of 3
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A size up of the structure is very important.
Height of building will also have an impact.
Wind can alter ventilation.
Bad weather affects smoke’s ability to travel.
Through proper ventilation the fire’s ability to
extend can be removed.
Fire and Its By-Products
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During combustion energy is released.
Molecules reunite to form new substances.
These substances can be caustic to humans.
Ventilation will remove some substances.
Ventilation has many other benefits.
Flashover, backdraft, and rollover can occur
without ventilation.
Fire Phenomena

Flashover.

Backdraft (smoke explosion).

Rollover.
Flashover
Light, smoke, and heat are liberated as
part of the combustion process.
 Everything in a confined area ignites at
almost the same time.
 It is important to know the mechanics of a
flashover to understand its development.

Backdraft (Smoke Explosion)
1 of 2
A rapid ignition of smoke.
 Incomplete combustion occurs as
oxygen levels decrease.
 As fire consumes greater amounts of
oxygen, the production of CO increases.
 With the heat, pressure builds in the
confined space.

Backdraft (Smoke Explosion)
2 of 2
When an opening occurs, a billow of
smoke escapes.
 Cooler air causes air to contract.
 Mixture increases CO concentration.
 Once CO concentration reaches the flame,
components are primed for ignition.

Signs of Potential Backdraft
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Smoke-stained windows.
Puffing of smoke at seams and cracks.
Smoke pushing out under pressure.
No visible flames.
Heavy black smoke.
Tightly sealed building.
Large, open area or void.
Extreme heat.
Rollover
Heated products of combustion rise to
higher levels.
 Heated gases reach their ignition and
begin to spread across the room along the
ceiling.
 When the upper thermal layer is
disrupted, the heat is forced down.

Expanding Heat and Steam
What Needs to be Vented?
Without ventilation expanding heated
steam and smoke will roll over.
 Small voids and compartments need to
exhaust increasing pressure.
 Areas such as cockloft need to be
checked.
 Horizontal and vertical voids.

Areas to Vent
Mechanics of Ventilation
Ventilation is simply the movement of
air from high pressure to lower
pressure.
 Knowing the natural tendency of air
movement is important.
 Improvement of air conditions is crucial.
 Horizontal and vertical ventilation
conform to the same rules.

Mechanics of Ventilation

SYSTEMATIC removal of products of
combustion.
 Ventilation controlled fire.
Ventilation controlled fire
Ventilation Techniques

Break glass.

Ax.

Open doors.

Portable ladder.

Rope and a tool.
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Aerial ladder tip.
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Hook or pike pole.
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Negative pressure.
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Iron or Halligan.
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Positive pressure.
Types of Ventilation

Ventilation can occur using several
methods:
– Natural.
– Mechanical:
 HVAC.
 Smoke fans.
 Positive pressure.
 Hydraulic.

Objectives:
– Describe all safety concerns with vertical
ventilation
– Describe advantages and disadvantages of
vertical ventilation
– Describe common procedures for vertical
ventilation
– Demonstrate ability to determine roof
integrity
– Identify proper tools used during vertical
ventilation
Vertical Ventilation
This next section will cover Vertical
Ventilation, both on Residential and
Commercial Buildings
 We will cover the basics on how to
ventilate these types of buildings
 There are several types of material that is
used for the roof decking
 We will start out with the Residential
Roofs

Vertical Ventilation
Residential Roofs
 These types of roofs can be either flat or
pitched
 The procedure is fairly simple
 Whether the roof is pitched or not, the
procedure is the same


Vertical Ventilation
Tools
– Cutting
 Pick head or flat head
axe
 K12 Circular Saw (All
Engine Companies)
 Chain Saw (T82)
– Stripping
 Pike Pole
 Rubbish Hook (T82)

Existing Roof Openings
– Scuttle Hatches
 Commercial Occupancies
– Skylights
 Residential and
Commercial
– Air Handlers
 Residential and
Commercial
– Exhaust Vents
 Commercial
– Attic Vents
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Safety Concerns
–
–
–
–
One of the most dangerous jobs on the fire scene
Use of power tools
Visibility
Smoke/Heat
 Full PPE
– Access/Egress
 Multiple points
– Roof Integrity
 SOUND IT!!, SOUND IT!!, SOUND IT!!
–Accessing the Roof
 Minimum on 2 access/egress points
–Place on different walls of building
 Ground or Aerial Ladders
–Aerial Placement
 Interior roof access
–Scuttles

Size Up the Roof
– Construction type and features
 Ridge Line/Truss Direction
 Weight Bearing Walls
 Lightweight Construction
 Age of Building/Roof
 Loads on Roofs
 Drop Offs
– Existing Openings
 Skylights, Scuttles, etc

Size Up
– Roof Covering
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Tile vs. Shingles
Torch Down
Metal
Synthetic Foam Membrane
– Signs of Integrity
 Sagging Roof lines
– Vents growing
 Fire Smoke Venting

Getting on the Roof
– Sound the Roof
 Before you step on the roof
 Strike the roof with a tool (axe, rubbish hook)
 Feel and sound solid
 Regularly sound the path you choose and stick to
the sounded path.
 Scan the roof continuously

Working on the Roof
– NEVER cross roof
diagonally
– Walk on ridges, trusses,
outside walls
– Work from roof ladders if
possible
– Work from aerials if
possible
– Consider safety hoseline
(controversial)

Open the Roof
– BE SAFE ALWAYS
– Never cut in line with your body or that of
your partner
– Work in teams of two minimum
– One person cuts, the other backs him up
– If you fall and begin to slide, flatten out and
your partner will jump on you

Open the Roof
– Inspection Holes
 Helps find direction
of trusses
 Triangle in shape
 1-2 foot per side

ALWAYS work on
the WINDWARD
– (Wind at your back)

Don’t get caught
down wind – that is
where the fire is
going

Louver Opening
– Fast and Efficient =
less time on roof
– Must know direction of
trusses/rafters
– NEVER stand on the
hole you are cutting
– Always work back to
your egress
Vertical Ventilation
The goal is to get a hole at least 4’ x 8’
 It can be cut in line with the trusses or
perpendicular to the trusses
 If the cut is made perpendicular to the
trusses, you have to cross at least three
trusses. Three on the top and three on the
bottom
 If the cut is made in line with the trusses,
you will only have to cross the truss once
at the top and one at the bottom


Louver Opening
1st Cut
Mark Trusses
2nd Cut
3rd Cut
4th Cut
Last Cut

After the hole is cut
– Open the ceiling
– Contact Command
– GET OFF THE
ROOF!!

Trench Opening
– Typically used in
commercial
– Long, narrow opening
– Assist in stopping the fire
spread
– Long time to accomplish =
long time on roof
– Can also be louvered
VERTICAL VENTILATION

Trench Opening
Hoseline

Trench Opening
– Defensive cut.
– Q-deck / rolled roof.
– Considered outdated
by some tactic and
strategy subject
matter experts.
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Summary
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–
–
–
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BE SAFE
Size up the roof
Sound the roof
Make your hole
Get OFF!!!
Fire Walls
Hose line
Hydraulic Ventilation
Negative Pressure Ventilation
Smoke Ejector
Structural Ventilation
Safety Considerations
Will ventilation permit the fire to extend?
 Will the escape route be cut off?
 Will ventilation endanger others?
 Are firefighters working in teams?
 Is there proper supervision?

Obstacles to Ventilation
Access.
 Security devices.
 Height.
 Poor planning.
 Unfamiliar building layout.
 Ventilation timing.
 Cut a roof/open a roof.

Factors Affecting Ventilation
Partial openings.
 Partially broken
windows.
 Screens.
 Roof materials

Dropped or
hanging ceilings.
 Building size.
 Weather.
 Opening windows.

AN ANALYSIS OF POSITIVE
PRESSURE VENTILATION
HushCompartment
#4
QuantumCompartment
#5
POSITIVE PRESSURE
VENTILATION
TODAYS FIRES PRODUCE 20,OOO
BTU’s PER POUND COMPARED TO
8,000 BTU’s 10 TO 15 YEARS AGO.
 USE OF PLASTICS AND MODERN
CONSTRUCTION MATERIALS

POSITIVE PRESSURE
VENTILATION

INCREASED CO AND TOXIC GASES

NEW TECHNOLOGY IN PROTECTIVE
EQUIPMENT.

TYPE V CONSTRUCTION- LIGHT WEIGHT
ADVANTAGES
ADVANTAGES OVER NATURAL
VENTILATION ARE OBVIOUS
 PPV VS. NEGATIVE PRESSURE

– PERSONNEL ARE NOT EXPOSED TO
INTERIOR ATMOSPHERES
– FIRE GASES ARE NOT EXPOSED TO
BLOWERS
ADVANTAGES
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- BLOWERS RUN MORE EFFICIENTLY
- INTERIOR DOORWAYS AND HALLS ARE
UNOBSTRUCTED
- NO NEED FOR DROP CORDS OR “Z” BARS
- LESS NOISE AND CONFUSION
- REDUCED AIR AGGITATION INSIDE
STRUCTURE
ADVANTAGES
- SUPERIOR IN SPEED AND EFFICIENCY
 - TWICE AS EFFICIENT IN REMOVING
CONTAMINATES
 - HEAT AND SMOKE DIRECTED AWAY
FROM EXITS OR UNBURNED AREAS

ADVANTAGES
MORE EFFICIENT IN ROOMS WITH
VAULTED CEILINGS
 EQUALLY EFFECTIVE WITH HORIZONTAL
OR VERTICAL VENTILATION
 HAS MINIMAL EFFECTS ON SMOLDERING
DEBRIS- IFSTA

CHAPEL HILL STUDY
1300 SQ. FT. SINGLE FAMILY DWELLING
 NATURAL VENTILATION- CO LEVELS
OVER 600 PPM IN 3.5 MINUTES AFTER
IGNITION. REMAINED AT OVER 100 PPM
FOR 20 MIN. DESPITE VENTILATION
EFFORTS

CHAPEL HILL STUDY
PPV PRIOR TO FIRE ATTACK.
 400 PPM IN 3.5 MIN.
 0PPM IN 16 MIN.

PPV AFTER FIRE ATTACK
 600PPM IN 5 MIN.
 0PPM AFTER 16 MIN.

CHAPEL HILL STUDY
DECREASE IN SMOKE CONDITIONS AND
OTHER TOXIC GASES-CYANIDE
 REDUCED TOXICITY FOR VICTIMS
 EASIER FOR FIREFIGHTERS TO LOCATE
VICTIMS
 50% OF RESIDENTIAL DEATHS DUE TO
CO INTOXICATION

CHAPEL HILL STUDY
MOST RESIDENTIAL FIREFIGHTER
DEATHS ARE DUE TO DISORIENTATION
AND EXHAUSTING AIR SUPPLIES
 IF USED IN HORIZONTAL APPLICATIONSREDUCED COLLAPSE

GUILFORD COLLEGE STUDY
TWO STORY 1800 SQ. FT. SINGLE
FAMILY DWELLING
 PPV PRIOR TO WATER
 PPV AFTER WATER
 ATTEMPT TO MOVE FIRE WITH PPV

GUILFORD COLLEGE STUDY
INCREASED VISIBILITY AND REDUCED
HEAT
 INITIALLY AND TEMPORARILY
INCREASES HEAT IN THE BURN ROOM
 PPV PLACED BEFORE WATER IS MORE
EFFECTIVE IN HEAT REMOVAL IN
AREAS DIRECTLY EFFECTED BY THE
FIRE

GUILFORD COLLEGE STUDY

“ AT NO TIME WAS FIRE VISUALLY SEEN
BEING PUSHED THROUGHOUT THE
STRUCTURE EVEN WITH AN EXHAUST
PORT OPENING IN THE INCORRECT
PLACE, OR INCORRECT SIZE.”
U.S. COAST GUARD STUDY
FIREFIGHTER SKIN TEMP. PRIOR TO
EVOLUTION WITHOUT PPV WAS 90.8
DEGREES- 100.3 AFTER
 SKIN TEMP. 94.8 WITH USE OF PPV

HISTORY
INTRODUCED BY THE LOS ANGELES CITY
FIRE DEPARTMENT OVER THIRTY YEARS
AGO
 VERY CONTROVERSIAL
 USUALLY DUE TO DEPARTMENTS THAT
ARE NON-RECEPTIVE TO CHANGE

IMPLEMENTATION

SOP’s MUST BE USED TO PREVENT
TRAGIC CONSEQUENCES

PERSONNEL MUST BE WELL TRAINED ON
MECHANICS AS WELL AS THEORY
IMPLEMENTATION
THOROUGH SURVEY
 EXHAUST OPENING BETWEEN ¾ TO 1
AND ¾ THE SIZE OF THE OPENING
 EXHAUST OPENING AWAY FROM
POTENTIAL VICTIMS
 PLACE FAN ON UNINVOLVED SIDE OF
THE STRUCTURE

- 9,000 TO 15,000 CFM MINIMUM

IMPLEMENTATION

IF POSSIBLE, USE PPV ON THE
WINDWARD SIDE OF STRUCTURE

ENTER STRUCTURE 15 SECONDS
AFTER IMPLEMENTATION
IMPLEMENTATION
PULL CEILING IMMEDIATELY AFTER
ENTERING STRUCTURE
 OPEN LINE OF COMMUNICATIONS
 PROBLEMS WITH PPV ARE USUALLY
ASSOCIATED WITH LACK OF TRAINING
OR DISREGUARD OF THE CONCEPT

IMPLEMENTATION
NOT RECOMMENDED FOR CURTAIN WALL
OR BALLOON TYPE CONSTRUCTION
 GIVES AN INITIAL INCREASE OF OXYGEN
TO FIRE
 CREWS MUST BE ABLE TO READ SMOKE
CONDITIONS
 KNOW YOUR EQUIPMENT

BEDROOM
2
BEDROOM
1
GARAGE
KITCHEN
ROOM
FAMILY ROOM
BEDROOM
3
DINING
BATHROOM
BEDROOM
BEDROOM
2
3
DINING
ROOM
KITCHEN
FAMILY ROOM
BEDROOM
1
GARAGE
BATH
BEDROOM
BEDROOM
2
3
DINING
ROOM
KITCHEN
FAMILY ROOM
BEDROOM
1
GARAGE
BATH
OTHER APPLICATIONS
DUMPSTER OR CAR FIRES
 OVERHAUL

Ventilation nightmare
SUMMARY
ESTABLISHED A NEED TO VENTILATE
 PPV REDUCES CO AND OTHER TOXIC GAS
LEVELS
 IMPROVES FIREFIGHTER SAFETY BY
INCREASING VISIBILITY
 SAFER AND FASTER THAN VERTICAL
VENTILATION

SUMMARY
MORE EFFECTIVE THAN NEGATIVE
PRESSURE VENTILATION
 REDUCES FIREFIGHTER BODY
TEMPERATURES
 LESS TIME ON TASK
 EFFECTIVE WHEN CLEAR
UNDERSTANDING OF CONCEPT AND
MECHANICS

SOP Review
Vertical Ventilation
Residential Roofs
 These types of roofs can be either flat or
pitched
 The procedure is fairly simple
 Whether the roof is pitched or not, the
procedure is the same
