TB 90 - Fire Burns Flashcards
Steam can cause full thickness burns to unprotected skin with less than _____ seconds exposure
three seconds
A major cause of burns to firefighters is the disruption of the THERMAL LAYER by the use of _________.
high flow spray nozzles… this causes superheated steam being pushed down to a FF’s level.
(This is considered a CONVECTIVE heat source)
A Firefighter caught in a flashover, just ____ feet inside a room, will be exposed to temperatures of 1,000 to 1,500F, and direct flame impingement for at least ____ seconds.
5 ft
2 sec
The six observable or measurable factors in a Class “A” fire are:
- Input heat
- Fuel
- Oxygen
- Proportioning of the fuel/air mixture
- Mixing of the fuel/air mixture
- Uninhibited chain reactions between active fuel/air molecules
BTU or British Thermal Unit is a basic UNIT OF HEAT.
A BTU is the amount of heat required to raise the temperature of ONE _____ of water _____ degree fahrenheit.
Pound
one
_______ is the THERMAL CAPACITY of a substance. It is the number of BTU’s required to raise the temperature of one pound of a substance one degree fahrenheit
Specific Heat
(the specific heat of WATER is ONE BTU).
Heat is transferred in what three ways?
- Radiation - transmitted similar to LIGHT WAVES
- Convection - heat through motion of a heated FLUID
- Conduction - transfer of heat through MATTER
What is the primary HEAT TRANSFER method within structures and is responsible for the majority of fire and SMOKE SPREAD within structures?
Convection
Fire extension through CONDUCTION occurs only in RARE CIRCUMSTANCES, but still must be considered at many fires.
The primary consideration relative to CONDUCTIVE heat transfer is __________.
-structural integrity
(The transfer of heat from metal connectors to wooden structural members, weakening those connections, is a major cause of structural collapse, particularly involving any type of truss construction.)
HEAT is the MOST DANGEROUS and threatening PRODUCT of COMBUSTION for the following reasons:
- Products of combustion are carried vertically and horizontally (MUSHROOMING) to remote areas of the structure.
- Through convection and radiation new fuel sources are heated to their ignition temperatures and contribute to rapid fire spread and extreme fire behavior.
- Metal to wood structural connections weaken.
Fire Progress and Development in the GROWTH STAGE
The rate of combustion, fire intensity, and the total combustion product output are governed by SIX major factors:
- The AMOUNT of exposed combustible surface.
- The ARRANGEMENT of the combustible surfaces.
- The TYPE of fuel source.
- The NATURE of the combustible surfaces.
- The RATIO of combustible surface to room or area volume. (PRIMARY FACTOR that determines the time to Flashover)
- The amount of available AIR flow or ventilation.
Fire Progress and Development
The PRIMARY FACTOR that determines the time to Flashover or full room involvement, assuming that there is adequate air supply is?
The RATIO of combustibles to room or area volume
Fire Progress and Development
Growth Stage- The rate of sustained combustion is largely determined by available ________.
ventilation or air flow.
Fire Progress and Development
The fully developed stage can be identified by the ________ (upward/horizontal/downward?) portion of the fire curve.
horizontal
What are the stages in the development of a fire?
-Growth Stage
-Fully Developed Stage
-Decay Stage