CFD - Kev > Chapter 14 - Fire supression > Flashcards

Chapter 14 - Fire supression Flashcards

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1
Q

Ways to interrupt the fire tetrahedron

A
  • Temperature reduction
  • Fuel removal
  • Oxygen exclusion
  • Chemical flame inhibition
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2
Q

Temperature reduction

A

Extinguishment is cooling with water. Enough water must be applied to absorb the heat being generated and stop the gas phase chemical reaction.
- Reduces temp of a fuel to a point where is does not produce sufficient vapours to burn
- Can control burning gases and reduce temp of hot products of combustion in the upper gas layer
- Reduces heat flux from upper layer
- Reduces potential of flash over

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3
Q

Water

A
  • Absorbs significant heat with its greatest effect when it is vaporized into steam. When converted to steam, it absorbs 5 times more energy than warming the liquid to the boiling point.
  • It also rapidly expands approx. 1700 times. Avoid when doing interior FA due to reduced visibility, steam burns, and disruption of thermal layer
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4
Q

Fuel removal

A
  • More common tactic at ground cover fires, exterior stacked material fires, vehicle fires and flammable liquid/gas fires (careful of run off)
  • Stopping the flow of a liquid fuel
  • Closing valves to stop the emission of gaseous fuels
  • Moving solid fuels out of the path of the fire
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5
Q

Oxygen exclusion

A

Reducing available O2
- Method used for stove top fires, when a cover is placed on a pan of burning grease
- Flooding a compartment with CO2 displaces O2 but makes environment oxygen deficient
- Blanketing some fuels with foam can displace O2 (none will work on fuels that are self oxidizing such as ammonium nitrate found in fertilizer)
- Door control to limit O2 to fire

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6
Q

Chemical flame inhibition

A
  • Dry chemicals, Halons, clean agents, inhibit or interrupt the combustion reaction and stop flame production.
  • Effective on flaming fires.
  • Impractical on smoldering fires because there is no effective means to cool the fuel and stop the chemical chain reaction.
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7
Q

Use a TIC or apply a small amount of water on the surface of the door in order to check for heat. If door is very hot, water will evaporate and convert to steam.

A

True

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8
Q

Fast air movement in at the bottom and smoke moving out at the top indicates an active fire in the structure

A

True

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9
Q

High volume of turbulent smoke and a low neutral plane (pre flashover conditions), apply water to the hot gas layer and do not enter

A

True

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10
Q

Gas cooling

A

Way of reducing heat release from the hot gas layer. Effective technique when faced with a shielded fire (a fire you cannot see from the door way because it is located in a remote part of the structure or objects are shielding the fire).
- Water droplets will fall out of the smoke layer in greater quantities as the layer cools

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11
Q

Direct attack

A

Using a solid or straight stream uses water most efficiently on free burning flames. Water is applied directly onto the burning fuels until fire is extinguished.

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12
Q

Indirect attack

A

Can be made from inside or outside structure. Directing the stream toward the ceiling to cool the room or by banking the stream off walls. Produces more steam and should be coordinated with ventilation.
- Do not upset the thermal layering; the steam produced will begin to condense, causing the smoke and heat to drop rapidly to the floor and move sluggishly thereafter

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13
Q

Combination attack

A

Combines cooling the hot gas layer using indirect attack with direct attack on the fuels burning near the floor level. Nozzle pattern U, N, Z, T or rotational manner.

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14
Q

Transitional attack

A

Uses an exterior fire attack through a ventilation opening to help a fire transition from vent limited to fuel limited. Reduces potential of flashover and makes a more survivable interior environment. Following this, an interior attack crew can more easily make entry and reach the seat of the fire.

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15
Q

Standpipe systems

A
  • May be required in structures 3 stories or higher.
  • Most located in stairwells, corridors, or protected stairways.
  • If unprotected, connect on floor below. If found in protected, can connect on fire floor.
  • Flake extra attack hoseline on first landing above fire floor so it will feed more easily into the fire floor
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16
Q

Below ground fires

A

Some of the most difficult and dangerous fires for FF
- If basement unfinished, exposed floor joists are exposed and will fail sooner than a ceiling protected with drywall.
- Supporting joists can collapse before the floor decking was burned through
- Interior and exterior enclosed stairwells can act as flow paths for smoke, flames, and heated gases

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17
Q

Basement fires are hot, and opening a vent point to allow O2 to enter is going to create more problems unless ventilation is coordinated with water applications

A

True

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18
Q

Exposure protection

A

Preventing a fire from spreading to unaffected areas. Unaffected areas are referred to as exposures and may exist inside or outside of a structure.

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19
Q

Interior exposure

A

Generally involves closing doors or other openings between the fire area and the unaffected area and the proper use of tactical ventilation to ensure limited smoke movement. Controlling ventilation with positive pressure in adjoined, uninvolved areas of a structure can also pressurize those areas and isolate the fire to one area. Passive forms of exposure protection such as fire rated walls and doors are also used to prohibit fire and smoke movement.

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20
Q

Exterior exposures

A

Either remove the endangered persons, property, or items or apply a protective spray of water or foam extinguishing agent between the fire and the exposure.

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21
Q

Supporting fire protection systems

A

Should work with the system to control the fire. Most designed with control mode sprinklers. Only intended to control fire growth and prevent flashover. Complete suppression before turning off the system or unless given orders by IC.

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22
Q

FDC

A

Fire department connection
- Allow a pumper to supplement the water supply and pressure in a structures sprinkler or standpipe system.

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23
Q

Closing a main control valve

A

One means to stop the water flow from activated sprinkler heads (can also use wedges). Located between the sprinkler system and the main water supply. Control valve usually located directly under the sprinkler alarm valve, the dry pipe or deluge valve, or outside the building near the sprinkler system it controls.

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24
Q

Types of control valves

A

Outside screw and yoke (OS&Y) valve
Post indicator valve (PIV)
Wall post indicator valve (WPIV)
Post indicator valve assembly (PIVA)

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25
Fire department personnel are not responsible for turning utilities back on and should not attempt to do so.
True
26
Only use the main power shutoff at the meter or the breaker box to shut down electricity to a structure.
True
27
Solar panels and photovoltaic panels
Most have 2 shutoff switches one on each side of the power inverter. Also a shutoff switch on the electric meter. Closing these will shut off power inside the structure, but it will not turn off the solar panel array as long as there is any amount of natural or artificial light, the panel is always on and generating power. Avoid these when performing tactical ventilation.
28
Natural gas
Pure form is Methane. Flammability range of 5% to 15% but is nontoxic. Lighter than air so it tends to rise. Classified as a asphyxiant because it may displace air in a confined space and lead to suffocation. - No odour but utility companies add Mercaptan, which gives it a rotten egg smell. - Meter usually located outside structure near the foundation. Can be inside in basement or mechanical space. - When open, the tang (rectangular bar) is in line with the pipe.
29
Liquefied petroleum gas (LPG)
Also known as bottled gas. LPG refers to fuel gases stored in a liquid state under pressure. 2 main gases BUTANE and PROPANE(most used). - propane has no natural odour, but added mercaptan gives it the distinct smell. Non toxic. - LPG 1.5 times heavier than air. - explosive range of 2-9.5%. - lpg leak produces a visible cloud of vapour that hugs the ground
30
Vehicle fires
Variety of power sources; gasoline, diesel, electricity, hybrids, compressed or liquefied natural gas (CNG or LNG), biofuels, and hydrogen
31
continued..
- When approaching, avoid front and back. Careful of struts that can explode. - Broken fuel lines can be crimped or plugged - broken or punctured fuel tanks can be plugged with rubber/plastic/wooden plugs, sealed with fuel resistant sealing compound
32
Vehicle fire attack
- uphill to avoid leaking fuels running downhill - attack at a 45 degree angle to protect from pneumatic or hydraulic struts - issue "all clear" when all occupants are out - if combustible metal compounds become involved, apply large amounts of water while applying Class D extinguishing agent to the metal
33
Overhaul of vehicle fires
Disconnecting battery, securing air bags, and cooling fuel tanks and any intact sealed components.
34
Before attempting forcible entry, cool the front and rear bumper struts to prevent accidental activation from heat exposure.
True
35
Engine compartment fires
- direct hose stream through the grill or air scoop - piercing nozzle (careful if hybrid or EV car for risk of electrocution) - make or cut opening - use a pry tool to create an opening between the hood and fender
36
Natural gas vehicle fuel (CNG and LNG)
- diamond logo may be affixed to the front and rear of vehicle - fuel tanks usually located in trunk area, under side panels or in open bed of pickup trucks - can rupture if exposed to fire resulting in an explosion
37
LPG vehicle fuel
- known as propane, 3rd most common after gasoline and diesel - allow fire to self extinguish - can use foam or water when necessary - stay clear of vapour clouds
38
EV or hybrid
- batteries can be in engine compartment, trunk area, or under vehicle - most contain a 12 volt battery system - takes approx 5 minutes for energy in the system to dissipate - do not cut orange high voltage cables
39
Ethanol/methanol
Gasoline blends.
40
Biodiesel
Blend of liquids from natural plants and diesel. Yellow liquid. Flash point of 130C (266F).
41
Hydrogen
Colourless, odourless, and non-toxic. Ignition temp of 500C (932F). Flammability range of 4-75%. - do not extinguish fire, instead protect exposures and allow fuel to burn off - do not cut C posts which contain the vents
42
Because small structures are generally used for storage, you should assume that chemicals, flammable/combustible liquids, explosives, or illegal materials may be inside the buidling
True
43
3 main influences on ground cover fire behaviour
Fuel Weather (most significant) Topography
44
3 basic types of ground cover fires
Ground fire- burn in the layer of dead organic matter (called humus) that generally covers the soil in forested areas. Slow moving, smoldering fires Surface fire- the surface or crawling fire most common type, burning on the soil surface consuming low lying grass, shrubs, and other vegetation. Crown fire- crown or canopy fires are wind driven, high intense fires that move through tree tops of heavily forested areas.
45
Gnerally, O2 and fuel are always present where ground cover fires is found.
Adding a natural or human made ignition is the last remaining element needed to stare fire
46
Topography
Refers to earths surface features. Steepness of slope affects the rate and direction of a fires spread. Faster uphill than downhill.
47
Parts of a ground cover fire
Origin- area where fire started Head- part of ground cover fire that spreads most rapidly Finger- Long narrow strips of fire extending from the main fire Perimeter- outer boundary Heel- rear of a ground cover fire, opposite of the head Flanks- are the sides of the fire Spot fire- flying sparks or embers landing outside the main fire Islands- patches of unburned fuel inside the fire perimeter Green- area of unburned fuels next to the involved area Black- area in which the fire has consumed or blackened the fuels
48
Direct attack
Action taken directly against the flames at its edge or closely parallel to it
49
Indirect attack
Used at varying distances from the advancing fire. Used against fires that are too hot, too fast, or too big.
50
Flank attack
Normally used for moderately intense fires and can be either direct or indirect. Begins at the anchor point (road, highway, body of water, previous burn)
51
Parallel attack
Form of indirect attack. Creating a control line quickly using bull dozers or other heavy equipment.
52
Fire lines
Parts of control lines along which fuel and sometimes earth are removed to create a fire stop. Starting from an anchor point. - as FF use shovels to create the fire line, they can throw the dirt onto the fire to cool and smother the fire
53
LACES
Lookout Anchor points Communications Escape routes Safety zones
54
Most vehicle fires
- 2 x 44mm hand lines (attack/back up) - for large vehicle fires use 65mm hand line - NEVER turn your back on the fire
55
Vehicle fire attack
Approach vehicle with charged hoseline upwind, uphill at a 45-90° to avoid possible strut or bumper explosion injury Using a Straight stream (Bumper), approach the vehicle by applying water to the ground to push/sweep any possible fuel leaks or debris towards the under carriage of the burning vehicle As you advance on the vehicle, adjust the nozzle from a straight stream to a 30° fog application; direct water application at the vehicle from bumper-to-bumper Continue to adjust the nozzle pattern while approaching the vehicle until you have a 60° fog pattern. Put the hose over your shoulder and the nozzle in to the vehicle compartment
56
Note
* There is no national requirement in Canada for markings to indicate the type of fuel used to power cars, trucks, and buses * As a result, you may have no visual indicators or idea about a vehicle's fuel source
57
Tactics for Bio-Diesel Vehicles
* Dry chemical * CO2 * Water * Foam (Class B)
58
Class A foam
The CFD employs the use of Class A foam on vehicle fires to penetrate the burning material and cool/dilute fire gases produced during a vehicle fire The main difference between Class A and Class B foam is that Class A foam attracts carbon and Class B repels it
59
Stacked and Piled Materials
- Use solid stream from a distance; then shift to a fog pattern - Once fire is reduced, move the nozzle closer using the fog pattern for protection - Break up or pull apart the material with a trash hook or pike pole
60
If there is any question of the hazard...
Protect Exposures Prevent Fire Spread Allow Structure to Self- Extinguish
61
Foam Fire Fighting
Separating - Creates barrier between fuel gases and ignition sources Cooling (CFD apparatus) - Lowers temperature of fuel and adjacent surfaces (Class A foam) Smothering - Prevents air from reaching the fuel and mixing with vapors and prevents release of flammable vapors Penetrating (CFD Apparatus) - Lowers surface tension of water and allows it to penetrate fires in Class A materials (Class A foam)
62
Making entry
A - air (open bale) V- volume P- pattern
63
Ignition Temperatures
Some of the factors causing variation in ignition temperatures are: * Size: Generally, the smaller the fuel particle, the easier it will ignite. * Shape of fuel or vegetation * Moisture content (heat of vaporization): This is the most important aspect of fire ignition temperatures * Quantity of fuel being heated * Velocity of air around the particle: Move convective laterally and increase rate of spread. This “heat” is necessary to start the reaction. Once started, fire produces its own life, thereby giving heat.
64
Wildland fuels can be divided into two main categories
Dead and alive. - single most important factor that determines fire behaviour is fuel moisture content.
65
Fuels
Fine- 1 hour fuels (grass, duff, small twigs) Light- 10 hour (twigs, stems) Medium- 100 hour (branches, small trees, logs) Heavy- 1000 hour (logs, trees, deep duff, peat)
66
Fuels are further classified as aerial, surface or ground (sometimes called subsurface).
True
67
Four variables influence fire weather:
1. Relative humidity * Greater than 60% - Humid * Less than 30% - Dry * Less than 20% - Very dry 2. Temperature 3. Wind 4. Precipitation
68
Rule-of-Thumb for Spread Increase
A fire burning uphill on a moderate slope (0% to 40%) will double in speed when going to a steep slope (40% to 70%), and it will double again when going from a steep to a very steep slope (70% to 100%).
69
Fire Danger Rating
* The probability of a fire starting * The estimated burning intensity * The rate of fire spread - low, moderate, high, extreme
70
Fire Status – Four Levels
Out of Control: Fire spread is not being contained. Being Held: The fire is not likely to spread under prevailing weather conditions. Under Control: There is no further spread of the fire. Extinguished: No heat on the fire exists.
71
Factors To Consider In Deciding Line Width
Typically, a fire line width of 1.5x the height of the burning material is a good place to start.
72
Safety Zones
A basic guideline for determining a required size of the zone is that no personnel or equipment should be within 4 times the flame height of anywhere the fire will be burning along the edge of the safety zone.
73
Retreat and return
Means firefighters retreat to safety zones and allow the fire to move through that area. When it is safe to do so, firefighters may return to protect structures or extinguish remaining fires.
74
Aspect
The direction with respect to sunlight and wind
75
South and west-facing slopes usually are covered with fine fuels due to reduced soil moisture as a result of solar heating
North and east-facing slopes can grow larger fuels due to the greater soil moisture.
76
Local wind behaviour
A good rule of thumb is, winds will be upslope during the warmer parts of the day and will change to down-slope during the cooler periods.
77
What extinguishing agent should be applied to the surface of a liquefied natural gas (LNG) fire found following a vehicle accident? p702
Use purple-K dry chemical agent or high expansion foam. Purple-K, also known as PKP, is a dry-chemical fire suppression agent used in some dry chemical fire extinguishers. It is the second most effective dry chemical in fighting class B (flammable liquid) fires after Monnex (potassium allophanate), and can be used against some energized electrical equipment fires (USA class C fires). It has about 4–5 times more effectiveness against class B fires than carbon dioxide, and more than twice that of sodium bicarbonate.
CFD - Kev
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