Fire Behaviour
- Heading Fire
- A fire which moves with the wind. It has long flame length, fast spread rate, and a high intensity.
- Flanking Fire
- A fire which moves at right angles to the wind. It has medium flame length, medium spread rate, and a medium intensity.
- Backing Fire
- A fire which moves against the wind. It has short flame length, low spread rate, and a low intensity. The released energy is concentrated closer to the ground and consumes more fuels on the forest floor.
- Spot Fire
- A fire which burns on all sides and exhibits heading, flanking and backing fire behaviour.
Ignition Techniques
- Back Firing
- An ignition techinque using lines of fire which are at right angles to the wind direction. The lines are ignited on the upwind side of a series of firebreaks and allowed to burn in an upwind direction exhibiting backing fire behaviour. Lines should be ignited simultaneously to ensure the timely completion of the burn.
- Strip Head Firing
- An ignition techinque using lines of fire which are at right angles to the wind direction. The lines should be ignited progressively in an upwind direction and burn towards each other exhibiting primarily a heading fire behaviour. Controlling the spacing between the lines ensures that one line burns into a previous line before the fire intensity reaches a high energy level.
- Strip Flank Firing
- An ignition techinque using lines of fire which are parallel to the wind direction. All lines should be ignited simultaneously on the downwind baseline and progress upwind at the same rate. The lines burn towards each other across the wind exhibiting flanking fire behaviour.
- Point Source Firing
- An ignition techinque similar to strip head firing except that spot fires are used instead of lines of fire. A series of spot ignitions spaced along a line spreads slower and builds up intensity slower than does a solid line of fire. The spots along a line are spaced far enough apart such that a spot heads into a downwind spot before its flank merges with an adjacent spot in the line. Controlling the spacing between adjacent spots controls the fire intensity.
- Pile Burning
- A point ignition technique that prolongs the burn time on a collection of heavy fuels to ensure complete combustion.
- Aerial Ignition
- A method of ignition using aircraft and a variety of ignition devices and techniques. A point source firing technique is used with a plastic sphere dispenser. A pile burning technique is used with a helitorch.
Ignition Devices
- Gelled Fuel
- A mixture of diesel fuel, gasoline and a gelling agent. Typical mix ratios are four parts diesel fuel to one part gasoline. The most common gelling agent is Flash 21.
- Aerial Ignition Device
- Small capsules which contain potassium permanganate. Once injected with ethylene glycol, the two chemicals react in a delayed spontaneous reaction to produce an intense ignition source. The capsules are more commonly in spherical form and for that reason are also known as ignition spheres, ping pong balls, Dragon Eggs, or Fireballs.
- Drip Torch
- A handheld ground ignition system that utilizes gelled fuel. The drip torch consists of a reservoir of fuel attached to a nozzle. Fuel is dripped out of the nozzle and past an igniter, allowing flaming drops of fuel to hit the ground. There are very many models available including Panama, Wildfire, and Cascade.
- ATV Drip Torch
- Terra Torch
- A vehicle mounted ground ignition system that propels a stream of flaming gelled fuel. Models include Firecon 1400, Buckmaster MkIII, and the Bishop Terra Torch.
- Helitorch
- An aerial ignition system that utilizes gelled fuel. The helitorch is slung beneath a helicopter and consists of a reservoir for the gelled fuel, a pump to dispense the mixture, and an igniter. It is best suited for discontinous fuels such as slash piles. Models include the Simplex 5400 and the Isolair Firefly II.
- Plastic Sphere Dispenser
- An aerial ignition system which utilizes aerial ignition devices. The dispenser is mounted in a helicopter and controls the injection and dispensing of the capsules. It is also known as a PSD, ping pong ball machine, dragon machine, or premo machine. Dispenser models include the Red Dragon, the Premo MkIII and the Raindance R2.
- Ignition Sphere Launcher
- A ground ignition system that utilizes Dragon Egg ignition spheres. The launcher injects the Dragon Eggs and propels them up to 100 yards using either springs or compressed gas. Handheld models include the PyroShot and PyroShot HS. The Green Dragon is an automated model.
