Fire 1

Question 1

Basic fire progression

Answer 1

The progression of a fire in a compartment can be divided in to four phases:
Developing fire.
Flashover.
Fully developed.
Decay.

Question 2

Fire progression

Phase 1 Developing fire

Answer 2

This is where the fire ins initially developing, usually starting at a relatively slow rate, and increasing with time.

Question 3

Fire progression

Phase 2 Flashover

Answer 3

Flashover is a thermally driven event. Once the compartment fire has grown enough it will flashover the entire compartment.
This changes from ‘a fire in a room to a room on fire’.

Question 4

Fire progression

Phase 4 Decay

Answer 4

This is where the fire will gradually die back as the fuel is consumed..

Question 5

Signs of flashover

Answer 5

Ventilation controlled, vented fire.
Painful radiant heat with crews forced low by the high temperatures.
Low turbulent neutral plane.
Fingers of flames through smoke.
Hot surfaces.
Increased rate of pyrolysis.
Increased turbulence of the neutral plane.

Question 6

Describe backdraught

Answer 6

Limited ventilation can lead to increased pressure as large amounts of gases build up. When air is introduced this fuel rich atmosphere reaches its flammable range.
All these gases then combust resulting in deflagration moving through the compartment and out the opening.
This is known as backdraught.

Question 7

Signs of backdraught

Answer 7

First consider:
How long has the fire been burning?
What sort of materials are involved?
Signs include:
Ventilation controlled, non-vented fire.
Lack of visibility.
Dirty smoke.
Smoke pulsating through small gaps & openings.
Air being drawn in (whistling noise)
Indicators of extreme heat - blistering of paint, high levels of heat indicated behind closed doors, crazing of glass in windows, blackening.

Question 8

Describe fire gas ignition

Answer 8

Flammable gases can build up in a separate compartments through voids, roof spaces or pyrolysis through walls.
Fire gas ignition is when these gases combust due to some form of ignition.
Looks similar to backdraught.

Question 9

Difference between backdraught/flashover and fire gas explosion

Answer 9

Both a backdraught and flashover occur within (or from) a fire room itself. A fire gas explosion is a event that occurs in a separate compartment.

Question 10

Purpose of a direct attack

Answer 10

The purpose of a direct extinguishment is to extinguish a fire by direct surface cooling of the burning combustibles using a jet or spray.
Settings are:
Stream attack of 115 - 475lpm
Stream, flow rate determined by intensity of the
fire.

Question 11

Purpose of a direct attack

Answer 11

The purpose of a direct extinguishment is to extinguish a fire by direct surface cooling of the burning combustibles using a jet or spray.
Setting are:
700kPa at the branch, stream, 115 - 475lpm.
Stream, flow rate determined by intensity of the
fire.

Question 12

Purpose of an exterior application

Answer 12

The purpose of an exterior water application is to support interior operations by applying water onto the fire as soon as possible.

Question 13

Purpose of an indirect attack

Answer 13

The purpose of an indirect attack is to extinguish a fire by creating large amounts of steam. This has the joint effect pf gas and/or surface cooling and excluding oxygen from the compartment. This method is generally used when the fire is fully involved or to suppress a suspected backdraught risk.

Question 14

Purpose of gas cooling

Answer 14

Gas cooling hose stream techniques are used to control the fire environment while firefighters advance during fire attack or to perform search & rescue. By cooling hot fire gases below their AIT, firefighters can prevent further fire spread and the potential for flashover.
Setting are:
700kPa at the branch, 115-23-lpm, 30-60 degree cone angle.

Question 15

Door entry procedure

Answer 15

1) Assess which way the door opens and position accordingly.
2) Using the branch, coat the door in water. The level of evaporation is a clue to the heat level behind (neutral plane).
3) Using the branch, short pulse twice above the doorway. This will cool and dilute the first escaping gases as you open the door.
4) Halfway through the second pulse, open the door long enough to insert the branch and direct a long pulse into the overpressure, observe conditions, then close.
5) Make a DECISION to enter or remain outside (and repeat process).

Question 16

Fire progression

Phase 3 Fully developed

Answer 16

After flashover the fire is fully developed, it will consume all available fuels in the compartment, leading to phase 4.