16 - Ventilation

Question 1

Ventilation definition

Answer 1

Ventilation, as applied to firefighting, is the planned and systematic release and removal of heated air, smoke, and toxic gases from a confined area and the controlled replacement of these products of combustion with a supply of cooler, fresh air.

Question 2

Pressure transfer

Answer 2

Pressure transfers from areas of high pressure to areas of low pressure. Heated had becomes buoyant causing it to rise. If the structure is confined, pressure will increase.

Question 3

Heat transfer, and by what methods?

Answer 3

Heat transfers from areas of high temperature to areas of low temperature.
Diffusion: move from high concentration to lower concentration.
Circulation: induced by pressure

Question 4

Traits of products of combustion

Answer 4

-fire is spread to surrounding materials via convection or radiation.
-pressure takes path of least resistance
-products of combustion are deadly
-products of combustion can spread sure

Question 5

Modern construction

Answer 5

Buildings retain more heat
Synthetic material increase fuel load
Construction is lighter materials so burn time is shorter before failure

Question 6

Advantages of ventilation

Answer 6

Makes structure more tenable, cooler, reducing risk of asphyxiation.
Increases visibility.
Fire can be located and isolated more rapidly.
Reduce smoke damage, salvage begins sooner.
Disturbance of thermal layering minimized.
Decrease horizontal spread.

Question 7

Deciding where to ventilate

Answer 7

Location of the fire
Occupancy and location of occupants
Exposures (int/ext)
Wind direction
Personnel and equipment available
Existing openings
Type of construction
Fire stage and progression

Question 8

Locating a fire techniques

Answer 8

Read smoke conditions
Thermal imaging camera
360 inspection

Question 9

Reading smoke four factors

Answer 9

Volume: larger volume indicates larger fire.
Velocity: faster the speed, greater the size of fire
Density: smoke is denser toward the seat of the fire
Color: determined by the product burning.

Question 10

Smoke colors

Answer 10

Gray: Wood or paper products
Black: hydrocarbons, plastic
Brown: nitrogen oxides
White: steam

Question 11

Black fire

Answer 11

High volume, density, velocity, black smoke. Signs of imminent discover. Only option is to aggressively chill and back out.

Question 12

2 types of exposures

Answer 12

Internal: routes by which heat and smoke travel to the exit may be the same corridor that occupants and ff use.
External: point of exit, products of combustion may course other adjacent structures or above exit to be heated to the point of ignition.

Question 13

Means to achieve Ventilation

Answer 13

Natural
Mechanical
Hydraulic

Question 14

Considerations for vertical ventialtion

Answer 14

You are working above the fire.
Wear full PPE.
Understand construction and effects of fire on roof types.
Know location of fire and wind direction.
Read conditions and roof weakness.
Evacuate roof once ventilation is achieved.
Observe for overhead hazards.
Deadloads on roof.
Snow and ice hazards.
Roof collapse.
Work on windward side.
Have safety line charged.
Always sound the roof before stepping onto it.
Self ventilating already.

Question 15

Types of roof openings

Answer 15

Kerf cut: slot cut to determine fire spread.
Inspection cut: triangle to get a visual.
Louver cut: rectangular opening.

Question 16

Trench (strip) ventilation: what to do

Answer 16

Cut only roof covering/sheathing. Do not cut through supporting members.
Cut across entire width of roof.
Make sure cut is made far enough forn fire spread so it can be finished before fire reaches you.
The ceiling below must also be breached.

Question 17

Conditions know before opening a roof

Answer 17

Know location of fire. Wind direction. Fire spread. Obstructions. Exposures.

Question 18

Opening a roof procedure

Answer 18

Stand upwind, on your roof ladder and Halligan.
Cut furthest away, along but not on a joist.
Cut top most, closest to pitch of roof.
Inspection triangle cut.
Bottom.
Close to the ladder.
Once sheathing is free, pull it up.
If no fire in attic, us like pole to open ceiling.

Question 19

Consideration for pitched roofs

Answer 19

Cut at highest point of structure.
Place ladder upwind of hole.
Sound for rafters. Mark location.
Strip off shingles.

Question 20

Arched roof considerations

Answer 20

If fire spread into trusses, do not go on roof.
Can’t use a ladder so work off ariel platform.

Question 21

Horizontal natural Ventilation procedure

Answer 21

Open leeward side to make use of negative pressure.
Then Open windward side to positively pressurize.

Question 22

Breaking windows

Answer 22

Always coordinate with fire attack. Breaking windows is irreversible, which can cause fire growth if done incorrectly. Breaking all windows simply adds air to the fire.
Keep a safe distance away from the window, position yourself on the windward side. Keep hands higher than the point of impact.

Question 23

Ventilation definition again.

Answer 23

Ventilation, as applied to firefighting, is the planned and systematic release and removal of heated air, smoke, and toxic gases from a confined area and the controlled replacement of these products of combustion with cooler, fresh air.

Question 24

Hydraulic Ventilation

Answer 24

Negative pressure from the interior using a fog stream enveloping 85-90% of an opening to entertain smoke out of the structure.

Question 25

Disadvantages of negative pressure ventilation

Answer 25

Equipment blocks access and egress to the structure. Firefighters must enter the structure to initiate npv. Equipment gets exposed to contamination. Less effective. Must use electrical fans only.

Question 26

What should the sizing of entrnece/exits be for ventilation

Answer 26

Ensure exit openings are proportional to the entrance opening or larger.

Question 27

If the fire exists in an under ventilated state, PPV should ______ be used, because...

Answer 27

Not be used. The addition of air into an under ventilated compartment could possible trigger a backdraft, smoke explosion or flashover. If fire is already self ventilating it may be safe, or it may make the fire more intense.

Question 28

Advantages of ppv. Disadvantages.

Answer 28

Established without entering contaminated environment. Air currents kept to minimum. Equipment doesn't block doorway. -introduces large volume of air into structure, which can intensify and spread fire.

Question 29

Fam placement for ppv

Answer 29

1 - 2 meters from opening. Tilt to adjust until cone covers.

Question 30

Hydraulic Ventilation limitations

Answer 30

Size of room. Size of exit opening. Exterior exposure proximity. Hoselines availability. Fire control. Wind direction. Time of year.

Question 31

High rise ventilation risks

Answer 31

Increased occupancy. Fixed windows. More logistical issues like door control and manpower. More time to establish ventilation.

Question 32

Vertical vent high-rise door control

Answer 32

Open roof access door, then work way down closing doors until fire floor and open those doors.

Question 33

Natural Stack effect

Answer 33

Hotter air inside, cooler air outside. Smoke ventilates out top of structure. Smoke rises until temperature equals ambient air.

Question 34

Reverse stack effect

Answer 34

Cooler air inside, hotter air inside. Smoke cools, and banks down contaminating lower levels.

Question 35

Mushrooming effect

Answer 35

Thermal layering due to physical barrier (no ventilation). Smoke spreads across top floor, then 2nd top and down.