Mfb Recruit Course 121 Structural Exam

Front 1

What is Fire?

Back 1

A rapid combination of oxygen and fuel in the presence of heat, characterised by flame, a body of incandescent heat that contains and sustains reaction, omitting light & heat.

Front 2

What is 'Vapour Density'?

Back 2

VD of air is 1. If the VD of a gas/vapour is greater than air (e.g 1.8) it is heavier than air, and if the VD of a gas/vapour is less than 1 (e.g 0.8) it is lighter than air. Most flammable gasses have a VD greater than 1.

Front 3

What is 'Specific Gravity'?

Back 3

The weight of a solid/liquid in relation to water. If greater than 1 the substance will sink, If less than 1 the substance will float on the surface.

Front 4

What is a carbon compound?

Back 4

Most flammable compounds built contain carbon. Carbon oxidises to form either carbon Dioxide or Carbon Monoxide.

C (solid) + o2 = Co2 (when sufficient o2 present)

2C (solid) + o2 = 2Co (monoxide) when insufficient o2 present

H2o, Co2 % 2CO = basic products of combustion.

Front 5

What is a Hydrocarbon?

Back 5

Compounds of hydrogen and carbon are known as hydrocarbons and make excellent fuels

Front 6

What are the 4 stages of combustion?

Back 6

1. Incipient Stage
2. Smouldering Stage
3. Flame Stage
4. Heat stage

Front 7

What are the two different flame types?

Back 7

1. Diffused flame (yellow) - only the outermost layer is exposed to the o2 mixture.
2. Premixed Flame (blue) - gas/vapour mixed with o2 and provide the mixture to be within flammability limits.

Front 8

What are the compounds/products of complete combustion?

Back 8

Water (h2o), Carbon Dioxide (Co2) and Nitrogen Oxides are released

Front 9

What are the compounds/products of in-complete combustion?

Back 9

Water (h2o), Carbon Dioxide (Co2), Nitrogen Oxides, Carbon Monoxide, Carbon & other products

Front 10

What is a consideration for flammable vapours?

Back 10

Some Solids and liquids give off flammable vapours at room temperature.

Front 11

What is Pyrolisis?

Back 11

Breakdown/Decompostion of a product through the application of heat which forms flammable vapours. This can occur at 80 degrees, and will occur in wood at 150 - 200 degrees.

Front 12

What are two examples of pyrolisis?

Back 12

1. Oil soaked rags & coal heaps

- air penetrates and o2 reacts with oil/coal

- heat is given off but can't dissipate

- heat builds to point of auto ignition temp.

2. Haystacks and mulch heaps

- Bacteria releases heat, by-products of bacteria action react with o2 and release more heat

- heat can not dissipate , rises to auto ignition temp.

Front 13

What is an endothermic reaction?

Back 13

The initial heating of any material to release gas/vapour. Absorbs energy from its surroundings, making the surroundings cooler (e.g like ice melting)

Front 14

What is an Exothermic reaction?

Back 14

When heat is given off as a result of a reaction. Feel hot because they are giving off heat to the environment. (combustion of wood)

Front 15

What is heat?

Back 15

A measurement of energy, temperature is relative to the amount of energy the body has.

Front 16

What is a Flashpoint?

Back 16

Flashpoint of a substance is the lowest temp at which it gives off sufficient vapour to form a flammable mixture in the air, so on the application of an ignition source the vapours will flash but not continue to burn.

Front 17

What is a Flame or Firepoint?

Back 17

The lowest temperature which a substance gives off enough vapour to ignite on application of an ignition source, and continue to burn when the ignition source has been removed.

Front 18

What is an Auto-ignition Point?

Back 18

The lowest temp required to cause self sustained combustion in any substance in the absence of a spark/ignition source.

Front 19

What is the heat release rate?

Back 19

HRR = Heat/time

The greater the heat release rate produced the quicker the air will be consumed within the confined space

Front 20

What is conduction?

Back 20

The transfer of heat through a solid material from a region of higher temperature to a region of lower temperature.

Front 21

What is convection?

Back 21

Transfer of heat through a liquid or gas due to the circulation of the liquid or gas. Accounts for the majority of heat movement and spread throughout a structure.

Front 22

What is radiation?

Back 22

Transfer of heat energy by rays. Is a major factor in fire growth within a compartment

Front 23

What is direct burning?

Back 23

The physical contact of the flame with other available fuel

Front 24

Heat transfer summary

Back 24

1. Increases fire intensity
2. increases heat
3. increases fire gases and their temperature
4. reducing visibility
5. reduces chances of survival of trapped persons
6. compromises firefighter safety

Front 25

What are the steam expansion rates for 100 degrees and 450 degrees?

Back 25

100 degrees - 1:1700

450 degrees - 1:3500

Front 26

What 3 points can distinguish a fire in a structure from a fire in the open?

Back 26

1. Supply of oxygen to fire may be limited. Outdoors oxygen supply is virtually inexhaustible
2. Fire gases given off are trapped within an enclosure and build up. Outdoors they can dissipate.
3. Convected heat, in the form of hot fire gases, can accumulate within structure, resulting in much faster fire development than in the open, producing unique hazards.

Front 27

What are the stages of a compartment fire?

Back 27

1. Developing stage
2. Flashover Stage
3. Fully Developed stage
4. Decay Stage

Front 28

What is the Neutral Pressure Plane?

Back 28

Interface of the two regions of pressure, where the upper and lower pressures equalise & internal pressure is equal to pressure outside the compartment. This is not at a fixed height, as the volume of smoke and hot fire gases increase, the NPP will descend. The higher the NPP is the better the conditions will be for fire fighting.

Front 29

What is a flashover?

Back 29

The sudden and sustained transition from the developing stage to the fully developed stage of a fire within a compartment.

Front 30

What are the signs of a flashover?

Back 30

1. An adequately ventilated fire
2. Painful radiant heat forcing crews down low
3. Hot surfaces
4. Lowering of the neutral plane with flame fingers penetrating the smoke.
5. Increased turbulence of the NPP
6. Increased rate of pyrolysis leading to ignition of ALL combustible items in the compartment.
7. Flaming occurs throughout the whole volume of the compartment

Front 31

What is a Backdraught?

Back 31

The sudden introduction of oxygen in a burning room full of superheated gases which have been starved of oxygen. Oxygen mixes with the superheated gases creating an explosion of fire.

Front 32

What are the indicators of a Backdraught?

Back 32

1. History of fire
2. Fire with little or no ventilation
3. lack of visible flame
4. thick rolling black, yellow and white smoke
5. dirty brown smoke
6. smoke pulsating through small gaps & openings
7. Air being drawn in (whistling sound)
8. Heavy soot & blackening of windows
9. very low NPP

Front 33

What is Fire Gas ignition?

Back 33

Formation of variable sized flammable fire gases can occur in any compartment within a structure when a fire is present. They may be ignited by sparks or flying embers, which the resulting deflagration is likened to that of a backdraught. This occurs in a separate compartment to the fire.

Front 34

What is a Ventilation Controlled Fire?

Back 34

Where a fire has access to copious amounts of fuel with possible restrictions to air.

Front 35

What is a Fuel Controlled Fire?

Back 35

A fire having ample access to sufficient air to allow complete combustion.

Front 36

What is a ventilation induced flashover?

Back 36

A fire in a ventilation controlled state unable to flashover due to insufficient air supply can rapidly increase in intensity when ventilation is introduced by - opening doors, windows

- window failure

- burning through roof/ceiling

Front 37

What is achieved by Water Extinguishment?

Back 37

Reduces fuel - steam dilutes flammable gases

Reduces heat - Absorbs heat when water turned into steam

Reduces Oxygen - Steam limits the amount of oxygen reaching fire by smothering

Front 38

What are the three methods of extinguishment?

Back 38

Direct

Indirect

Gas cooling

Front 39

What is direct extinguishment?

Back 39

Method where the extinguishing agent is applied directly onto the burning fuel using a jet or spray

Front 40

What is indirect extinguishment?

Back 40

Method of applying water spray onto superheated surfaces and/or overheated gases in a compartment to create a mass of steam that displaces oxygen to smother the fire. Performed from outside the compartment.

Front 41

What is Gas cooling?

Back 41

Water spray into overhead superheated gases, to cool them below their ignition temperature to prevent further fire spread & potential for flashover. Need to adjust duration and frequency of water application to suit - fire intensity and amount of hot fire gases, temperature of the hot fire gases, size and volume of the compartment.

Front 42

What are the stats for the 38mm firefighting line?

Back 42

- 700kpa at the branch

- 115 - 450 L/min

- 2 lengths at 1000kpa

Front 43

What does B-SAHF stand for?

Back 43

Building

Smoke

Air Track

Heat

Flame

Front 44

What are the actions when gaining entry & whilst inside a compartment?

Back 44

1. Always apply correct door entry techniques
2. Ensure the fire does not get behind you, that rapid advance of the fire does not cut you off, or that your means of retreat are not blocked by falling debris
3. Keep the door of a room on fire closed until you are ready to attack the fire.