Unit 1 - Basic Concepts of Wildland Fire
Unit Objectives 1. Define basic terminology used in wildland fire. 2. Identify the elements of the fire triangle. 3. Describe three methods of heat transfer.
Parts of a Fire
Origin
Head
Flank (Flanks)
Rear or Heel
Perimeter
Finger
Island
Spot Fire Spotting occurs when small burning embers land outside the fire perimeter and start small fires.
Head Left Flank Right Flank Rear or Heel Origin Which flank is more active? Where would you start to fight this fire?
What are these two fire parts called? Pocket on right, finger on left
Fire Behavior Terms
Fire burning without flame and barely spreading. Smoldering Fire burning without flame and barely spreading.
Fire burning with a low flame and spreading slowly. Creeping Fire burning with a low flame and spreading slowly.
Fire spread rapidly with a well defined head. Running Fire spread rapidly with a well defined head. *Click on image to play video
Spotting Fire producing sparks or embers that are carried by the wind or convection that start new fires beyond the main fire Spotting occurs when small burning embers land outside the fire perimeter and start small fires. *Click on image to play video
Torching orching is characterized when trees occasionally burn from bottom to top. Torching can happen with individuals trees or small clusters of trees. Torching is frequently isolated and intermittent. This may be an indicator that fire behavior is increasing
Crowning Fire advances from top-to-top of trees or shrubs more or less independently of the surface fire. Fix so that the movie picture is visible while in non playing form Crowning occurs when a surface fire moves into and burns in the canopy of trees, independent from the surface. This is a very hazardous situation and tactics usually will involve air support and indirect attack *Click on image to play video
Flare up Sudden acceleration of fire spread or intensity, but of relatively short duration.
Firewhirl A spinning, moving column of ascending air rising within a vortex and carrying aloft smoke, debris, and flames. *Click on image to play video
What type of fire behavior is this? Fix so that the movie picture is visible while in non playing form *Click on image to play video
What type of fire behavior is this? *Click on image to play video
Other useful firefighting terms Anchor point Control line Fireline Mop-up Contained Controlled Chain
The Fire Triangle In order for a fire to occur, the three things must be present: Enough oxygen to sustain combustion. Enough heat to raise the material to its ignition temperature. Some sort of fuel or combustible material. All three elements must be present at the same time to have a fire. Fire will burn until one or more of the elements is removed. The interaction of the three equal sides of the fire triangle: heat, fuel and oxygen, are required for the creation and maintenance of any fire. When there is not enough heat generated to sustain the process, when the fuel is exhausted, removed, or isolated, or when oxygen supply is limited, then a side of the triangle is broken and the fire is suppressed.
What is the missing part of the fire triangle? Lightning, campfire, matches, train emissions, volcanos,etc. What are some sources of heat?
Heat Transfer Radiation Convection Conduction
Radiation Radiant heat can dry surrounding fuels and sometimes ignite the surrounding fuels
Convection The hot gases and embers which compose the smoke column can dry and ignite other fuels. *Click on image to play video
Conduction Heat is conducted from one fuel particle to another through direct contact.
What type of heat transfer do the arrows indicate? Convection Conduction Radiation
Exercise (open book) 1. What are the three methods of heat transfer? 2. The fire triangle consists of oxygen, heat, and ____________? 3. When is a fire controlled? 4. Should you fight fire without an anchor point? Why?
Review Unit Objectives 1. Define basic terminology used in wildland fire. 2. Identify the elements of the fire triangle. 3. Describe three methods of heat transfer.