Firing Devices (Fusees, Drip Torches)
Firing devices such as fusees and drip torches are widely used in both wildfire control and suppression and prescribed fire tactics.
In fire suppression tactics both devices are commonly used to burn wildland fuels that remain between the fire and the indirect fireline to secure that fireline. If the area between the fire and fireline is relatively small, then firefighters burn these areas out as fireline is being constructed. However, if the unburned area adjacent to the fireline is large, burn out operations may be delayed until a section of fireline is complete. This delay allows firefighters to reorganize and concentrate on lighting the unburned fuels and containing the fire within the fireline.
Adequate communication between all personnel involved in the operation is necessary during a firing operation. Whichever firing devise is used, communication is required with adjacent resources before and during lighting operations. Both suppression and prescribed fire operations require good planning before burning operations begin.
Selecting the firing device
Availability
The selection of a firing device is based upon availability, fuel moisture and arrangement, and the size of the fire.
Fusees are much lighter and more portable than drip torches. A half dozen are easily carried by a firefighter. When safe, firefighter can use a fusee to light fuels between the fire and the fireline. Burning off the fuels can prevent the fire from jumping the fireline and make a safer environment for firefighters. If the fire does happen to cross the fireline, the firefighters have the option of stepping into the adjacent burned area.
If a fire crew does not have any firing devices on hand, embers can be retreived from the fire itself and scattered throughout the unburned fuels as the crew builds fireline.
Fuel moisture
Fusees can be ineffective if fuels are too wet; for instance, early in the morning and late in the afternoon. During those times when fusees are ineffective firefighters have to either wait until the fuels dry out to light unburned sections between the fire and the fireline or use a different firing device. If the decision is to continue to burn the fuels, then a drip torch is an appropriate tool. The advantage of the drip torch is that it is a mix of 2/3 diesel to 1/3 gasoline. Diesel burns slowly, allowing the heat to dry the fuels and also heat the fuels enough to start the fire. Gasoline is used because it ignites the diesel more easily. The diesel-gasoline mixture is often very effective at burning out even the most troublesome fuels, because a large mass of heat can be quickly created which then effectively preheats adjacent fuels.
Fire size
The size of area with unburned fuels is another consideration for deciding between fusees and drip torches. Drip torches spread diesel-gasoline on wildland fuel and is more efficient than fusees when the area covered by fuels is relatively large. With a fusee, a firefighter must often stop and hold the heat from the fusee on the fuels for a minute or two until it is self-sustaining, whereas the drip torch leaves a diesel-gasoline mix on the fuels long enough to initiate a self-sustainiing fire.
In a prescribed burn, drip torches are the tool of choice since relatively large areas are treated. By applying a variety of burn patterns and having either a backfire spreading downhill or a backfire spreading into the wind, or running uphill or with the wind, fire spread and fire intensity can be controlled.
The use of drip torches in fire suppression or prescribed fire operations requires a lot of planning and more complex logistics. First, it can take several days to obtain the necessary number of drip torches. Second, a supply of fuel cans, of a size that can be carried in firefighters packs into the operation area, with appropriate backpack frames will also be needed if there is no helicopter support available. Third, in some cases the fire managers have to find a helicopter that is available and affordable to sling fuel to the fire location. Fourth, a ready supply of fuel, both diesel and gasoline, and the personnel to mix and transport it is needed. The igition crew and support personnel must have the appropriate training and briefing to complete the operation safely and efficiently.
In a really large prescribed burn, where it is ineffective, not feasibly possible, or unsafe to have personnel walk through an area with drip torches, a drip torch may be used to burn adjacent to the fire boundary while a specially equipped helicoper lights the interior.
Encyclopedia ID: p338
