Chapter 16 Ventilation

Question 1

What is Thermal layering

Answer 1

Thermal layering is the layering of heated gases according to temperature – the hottest gases tend to be on the top layer

Question 2

The firefighter must consider what four factors pertaining to the smoke:

Answer 2

• VOLUME
• VELOCITY
• DENSITY
• COLOR

Question 3

When reading smoke what is the relation between volume and velocity

Answer 3

“Volume sets the stage for Velocity”

Question 4

what Various products produce different colors of smoke. Take in mind though – it may not always indicate the true combustible burning.

Answer 4

Wood & paper products - Gray Smoke
Hydrocarbons, plastic - Black Smoke
Nitrogen Oxides - Brown/Copper Smoke
Steam – White

Question 5

What is BLACK FIRE and what is your only choice pertaining to it

Answer 5

is the term we give to high volume, high velocity, and extremely dense, black smoke. It is a sure indicator of an impending flashover. Treat black fire just as actual flames.

Your only choice is to “aggressively cool and back out”

Question 6

What are the Two types of exposures Firefighters will encounter

Answer 6

1. Internal
   ● The routes by which the heat and smoke travel to the exit may be the same corridor that the occupants and firefighters may be using for evacuation. Higher portions of a building could ignite with the use of horizontal ventilation. The path of the fire gases, as they exit the structure, carries the fire to other locations of the building.
2. External
   ● At the point of exit, the products of combustion may cause other structures adjacent or parts of the same structure above the exhaust opening to become heated to their ignition points.

Question 7

What are the 2 types of tactical ventilation and through what means can they be achieved

Answer 7

Vertical and Horizontal ventilation can be achieved through Natural, Mechanical, and Hydraulic means.

Question 8

What is a consideration when breaking the windows on a structure

Answer 8

Breaking all the windows on a structure will not increase the ventilation. Instead, it will only add more air to the fire causing it to grow. Do NOT break windows unless it is a planned and coordinated effort with fire attack or to use the Quick Attack Monitor for transitional attack. Even then you would only break one window where the fire is in order to knock it down directly with a straight stream

Question 9

What is a key point of ventilation?

Answer 9

Keep in mind – ventilation must be
coordinated with Fire attack –
it is a systematic and controlled
process involving coordination
of which areas to ventilate (ex.
breaking windows, opening
doors, roof cuts etc.)

Question 10

What are 3 types of Mechanical ventilation

Answer 10

1. Positive Pressure
2. Negative-Pressure
3. Hydraulic

Question 11

Where the fire exists in an under-ventilated state or where any warning signs preceding back draft are apparent, then PPV…

Answer 11

should not be used. It is well established that the addition of air into an under-ventilated compartment could possibly trigger a back draft, smoke explosion or even flash over.

Question 12

What are some advantages of PPV

Answer 12

can be establish without entering contaminated environments
Air currents are kept to a minimum
Equipment does not block doorways
Internal combustion equipment operates more efficiently (gas operated fans)
Equipment cleaning and maintenance is reduced
Noise levels are reduced within the fire building
It is effective in all types of occupancies
Heat and smoke can be directed away from paths of egress
It can be controlled
It is more effective than NPV or HV

Question 13

What are disadvantages of PPV

Answer 13

Must be coordinated with other sector
Introduces large volumes of air into a structure that if misdirected will intensify
and spread the fire.
Requires special equipment
Depends on a power source (water, electricity, fuel).

Question 14

When can HVAC systems be utilized to remove smoke and heat from a specific area in a high-rise

Answer 14

If personnel on site know how to operate the HVAC system.
The HVAC system is capable and design for that purpose
HVAC systems can range from simple manually controlled air movement systems to very sophisticated automated systems that have smoke removal capability and smoke control zones.

Question 15

What type of ventilation is Hydraulic ventilation and when is it used

Answer 15

Hydraulic ventilation is a form of
Negative Pressure Ventilation (NPV). Hydraulic ventilation is
performed by interior attack teams to quickly clear heat and smoke from a room.

Question 16

If Fire control has not been established, the use of Hydraulic ventilation may cause the fire to intensify or overtake the attack crews what can the fire attack crew do in this scenario

Answer 16

However, a fire attack crew inside the compartment on fire can knock down the flames, then turn the nozzle toward an opening (window) and hydraulically ventilate the room to get rid of the heated steam caused by hitting the seat of the fire. This is a great way to knock down a fire and clear a room before outside crews are set up for ventilation.

Question 17

How is hydraulic ventilation performed

Answer 17

A fog stream is directed through a window to cover 85-90% of the opening. The
moving water entrains air and generates a negative pressure. Before using hydraulic
ventilation in the fire room, it is important to initiate cooling the environment or hitting
the seat of the fire.
The Sector using Hydraulic ventilation should contact Fire Command prior to
ventilating,

Question 18

when Vertical ventilation must be established through stairways or hoist ways what order should flow path be established

Answer 18

Open the door at the point of exit first, and then work your way back to the fire floor ensuring doors to other floors are closed.

Question 19

Describe positive pressure ventilation.

Answer 19

Positive pressure - creates differentials in air pressure and forces air out.

Question 20

Describe negative pressure ventilation.

Answer 20

Negative pressure - fans pull smoke away from the interior.

Question 21

Describe hydraulic ventilation.

Answer 21

The hydraulic ventilation technique is used by interior attack teams using a fog
stream set on a wide pattern to cover 85% to 90% of an opening. It clears the
interior of smoke and heat by drawing air past the fog stream.

Question 22

Give four limitations of horizontal ventilation.

Answer 22

Four limitations of horizontal ventilation are listed below:
a. Horizontal ventilation will send the smoke, gases, or heat into the same corridors that fire fighters and building occupants are using. Rescue considerations come first.
b. Remember that hot gases rise during ventilation and may ignite neighboring structures. Make sure charged hose lines are in place before horizontal ventilation is started - unless the building must be opened to begin rescue operations.
c. Do not ventilate the windward side of a structure before opening the leeward side; you may disturb the delicate balance of thermal layers.
d. Do not obstruct the ventilation opening. Remember, air can’t get through an obstruction, keep low and out of the natural ventilation flow path.

Question 23

List five advantages of forced ventilation.

Answer 23

Five advantages of forced ventilation are listed below:
a. It is controllable.
b. It can supplement natural ventilation.
c. It is faster than natural ventilation.
d. It reduces smoke damage.
e. It aids in property conservation.

Question 24

List three disadvantages of forced ventilation.

Answer 24

Three disadvantages of forced ventilation are listed below:
a. It can “feed” the fire with fresh oxygen.
b. It requires a power source.
c. It requires special equipment.

Question 25

Define leeward and windward.

Answer 25

Windward: the side of the building the wind is striking Leeward: the opposite side of the building the wind is striking. In short, fresh air enters a structure windward and leaves it leeward.

Question 26

List five disadvantages of hydraulic ventilation.

Answer 26

Five disadvantages of hydraulic ventilation are listed below: a. Water damage to interior increases b. May deplete water supplies c. Not suitable for winter climates because of ice production d. Firefighters have to stay in a contaminated atmosphere to achieve ventilation e. Ventilation time relies on SCBA and it’s service time

Question 27

What factors should you consider when deciding where to ventilate a structure?

Answer 27

The factors that you should consider when deciding where to ventilate a structure are: a. Location of the fire- b. Location of occupants c. Interior and exterior exposures- d. Type of construction e. Purpose or use of occupancy- f. Extent to which the fire has progressed g. Condition of the building and its contents- h. Existing openings i. Direction of the wind- j. Available personnel and equipment

Question 28

Describe both vertical and horizontal ventilation and when they should be used.

Answer 28

Horizontal - Horizontal ventilation is defined as the horizontal channeling of heat, smoke and gases through wall openings such as windows and doors allowing cooler air to enter. a. Horizontal ventilation should be used when: i. buildings in which the fire is not large enough to require opening the roof ii. buildings with windows or doors close to the seat of the fire iii. buildings in which the fire involvement is below the top floor iv. Buildings in which fire has not entered structural voids or concealed spaces. Vertical - Is defined as the vertical channeling of heat, smoke and gases which is achieved by creating an opening above the fire either by means of existing openings or by cutting the roof. b. Vertical ventilation may be used in the following cases: ▪ Buildings with fire in the attic, the cockloft, or the top floor ▪ Windowless buildings with few exterior doors ▪ Buildings with large vertical shafts ▪ Buildings in which fire has entered structural voids or concealed spaces.

Question 29

Describe forced ventilation.

Answer 29

Forced or mechanical ventilation involves the use of fans, blowers, nozzles, and other mechanical devices to create or redirect the flow of air inside an involved space. Forced ventilation removes or reduces the effect of unstable and erratic winds. It provides a dependable, controllable airflow that gives us, greater control of heat and smoke movement.

Question 30

True or False. Trench ventilation is an offensive form of ventilation.

Answer 30

False: Trench ventilation, is a defensive form of ventilation

Question 31

List some of the safety precautions for vertical ventilation.

Answer 31

a. ALWAYS REMEMBER THAT YOU ARE WORKING OVER THE FIRE. b. Always wear full PPE and SCBA. c. Understand building construction and the effects of fire on the type of roof construction. d. Know the location of the fire, the wind direction and smoke conditions on the roof. e. Continuously read the roof for construction and weakness. f. Continuously observe the safety of roof crews. g. Evacuate the roof once ventilation has been established. h. Always test the roof by sounding. i. Observe overhead wires near the roof. j. Obstructions or dead loads on the roof. k. Snow and Ice create fall hazards as well as increasing the dead load on the roof and obscuring signs of roof weakening. l. Parapet walls create fall hazards onto untested roofs. m. Roof collapse (partial or complete). n. Maybe necessary to breach ceiling to accomplish ventilation o. Work on the windward side of the hole

Question 32

List some problems you may face with Hi-rise ventilation?

Answer 32

o Increased occupancy that is exposed to heat, smoke and fire gases o Fixed windows may alter the most efficient ventilation flow path. o Increased logistical issues – greater amount of door control, required manpower and equipment for effective ventilation. o More time is required to establish ventilation due to the size of structure.

Question 33

What is mushrooming?

Answer 33

Is the lateral and downward migration of smoke when it encounters a physical barrier

Question 34

**Definition of Ventilation**

Answer 34

**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.