Browse Back Issues

Recent Comments

Many Jobs Many Sizes

By Chris Cavette

           

Wildland fire apparatus come in all shapes and sizes for all budgets and terrains. Whether large or small, the best designs include features for improved safety and effectiveness.

Wildland fire apparatus are known by a lot of different names. Manufacturers may use one name and specifications, while departments may use another. NFPA standards may use yet another name and set of specifications to describe the same apparatus.

For large-scale wildland fires, many departments use the apparatus designations defined by the National Wildfire Coordinating Group as part of the Incident Command System. (See “What's in a Name?” on page 16.) These designations divide apparatus into different types based on the pump, tank, equipment and other factors. This system is commonly used by government wildland fire agencies.

For more local firefighting, many departments define wildland apparatus based on the overall weight of the vehicle — or more specifically on the weight classification of the vehicle chassis. Thus, light brush engines are usually built on light-duty truck chassis, medium brush engines are built on medium-duty chassis, and heavy brush engines are built on heavy-duty chassis. The chassis weight classification of an apparatus is determined by the size of the water tank and the weight of the equipment, personnel and other components.

Although there's nothing official or exact about this system of designation, it can help departments specify the appropriate size chassis for a particular application.

Light brush engines are the backbone of most wildland apparatus fleets. In many departments they're the only wildland apparatus on the roster and must be able to handle a variety of vegetation fires. These smaller engines are relatively inexpensive and maneuverable, and they can be operated by a crew of one or two.

Light brush engines are useful for attacking fires in grass and low brush. They also can be used in heavier fuels if the fire is small and the wind speed is low. Most light brush engines have water-tank capacities up to about 400 gallons, an engine-driven pump rated 50- to 100gpm, and a booster reel of hose. The bodies usually are mounted low on the chassis with a minimum of compartments. Class A foam, remote-control monitors and 4×4 drive are optional.

The most important consideration for this size apparatus is stability. Although some departments use light brush engines with high-sided bodies or with tanks up to 500 gallons, the overall vehicle weight and center of gravity must be considered. In some cases lightweight body materials can compensate for the extra load, but in other cases departments should consider moving up to a medium brush engine.

Other important considerations include adequate area lighting at the sides and rear of the apparatus to allow safe nighttime operations. Vibration-resistant lights, commonly used on some agricultural and construction equipment, often give good service for off-road operations. Ease of operation is important because of the small crew. Placing the compartments, pump controls and booster reels low provides quick access and is a big advantage.

Medium brush engines are gaining popularity because of their ability to carry more water, equipment and personnel. They're still small enough and light enough to maneuver on narrow roads and across open terrain, but they bring an added firefighting punch and a larger crew.

These mid-sized brush engines are most useful in areas where wildfires involve heavier fuels and have the potential to grow rapidly. They're sometimes also used for limited structural fire suppression in wildland-urban interface areas. Most have water tank capacitiess of about 500 to 650 gallons, a PTO- or engine-driven pump rated 200 to 500gpm, and several hundred feet of booster and flat hose. CAFS is a valuable tool for structure protection. The bodies are usually fully compartmented to carry a variety of equipment. Remote-control monitors and 4×4 drive are optional.

Stability is an important consideration for this size engine because the compartmented bodies tend to be relatively tall. Placing the water tank, pump and other heavy components low on the chassis helps lower the overall center of gravity. Ground clearance is also important, and the apparatus is usually designed with high angles of approach and departure.

Other considerations include the ability to rapidly deploy and repack hose. This is especially important in the bump-and-run tactics used for structure protection during shifting fire conditions. Area lighting is also important, as are adequate warning lights and reflective markings for operations on roadways.

The largest brush engines are designed to carry sufficient water for extended operations in remote terrain. Their oversized water tanks help maximize a department's firefighting capability in the critical first hours before outside help can arrive and while fires are still small.

Heavy and extra-heavy brush engines often are used to fight grass and brush fires in open rangeland where water sources are scarce and the number of personnel is limited. They're also sometimes used in forested areas to allow extended operations. Heavy engines have water tank capacities of about 750 to 1,200 gallons, while extra-heavy engines have tanks of roughly 1,500 to 2,500 gallons. Pumps are engine-driven and sized to match the fuel load — usually 100gpm or less. Hose and equipment are restricted to preconnected attack lines and hand tools. All-wheel drive is standard. Remote-control monitors and CAFS are optional, but they can significantly increase the firefighting capability and decrease firefighter fatigue.

Weight capacity and stability are important considerations for these apparatus because of the tremendous amount of water they have to transport across uneven terrain. Military chassis with heavy-duty, wide-track axles are sometimes used to carry the extra weight and provide a wider base for better side-slope stability. Low-profile tanks with proper baffling also are important. As their name suggests, these rigs are big and heavy. Special driving skills are required.

Standard water tenders equipped with pumps and preconnected hoselines are finding many applications in wildland firefighting situations. These multifunction apparatus can transport, dump or pump water wherever it's needed.

Some departments use attack tenders to provide a mobile water supply for a team of two or three light brush trucks fighting a running grass fire in open terrain. Others use them to support mop-up or controlled burn operations. In situations with road access, attack tenders can hit a fire by themselves using ground sweep nozzles, hand lines or monitors. Most wildland attack tenders have tanks of about 1,500 to 2,000 gallons, one or more dump valves, PTO pumps rated at 500gpm and several preconnected hand lines. This configuration provides a good balance of weight, firefighting capability and water supply. All-wheel drive, foam systems and remote-control monitors are optional.

Although these apparatus are used primarily on paved or graded roads, stability and weight capacity are important considerations. Safe operation involves proper speed control and a knowledge of the vehicle's limitations when negotiating high-crowned roads, soft soils or sharp grade changes.

Other considerations include proper radio equipment to allow communications with other units during rapidly changing fire situations. Adequate warning lights and reflective markings are important for fill site operations along roadways. Area lighting on the sides and rear provide an additional measure of safety at night.

Wildland apparatus operate under different conditions than structural apparatus and they need different specs. The 2006 edition of the NFPA 1906, Wildland Fire Apparatus, defines the specifications for apparatus “designed primarily to support wildland fire suppression operations.” It applies to wildland apparatus contracted for on or after July 1 and includes those with slip-on pump/tank units.

The specifications found in NFPA 1906 differ from those in NFPA 1901, which covers structural apparatus. Among the notable differences are the requirements for pumps, tanks, hose, equipment, ground clearance, side-slope stability and angles of approach and departure. Departments should be familiar with the provisions of the latest edition of NFPA 1906 before they specify wildland apparatus.

Chris Cavette is the senior editor of In Service, an apparatus maintenance section and Web site published by Fire Chief magazine.

Wildland apparatus are sometimes called “brush trucks,” “grass rigs,” “patrol pumpers” or many other names. The use of such designations is acceptable when departments are fighting fires within their own jurisdiction, but when they are participating in large-scale, multiagency wildland fires, the most effective procedure is to use the Incident Command System designations defined by the National Wildfire Coordinating Group.

Under this system, all pumpers are called “engines,” all water-carrying wheeled vehicles are “tenders,” and all water-carrying fixed-wing aircraft are “tankers.” These designations are further broken down by types based on the water capacity, equipment, personnel and other factors. (See table below.)

Using this system gives incident commanders a better understanding of the capabilities of the apparatus available to them, which allows safer and more effective deployment. For example, rather than “We're bringing a brush truck,” departments should say, “We're bringing a Type-6 engine.” That tells an incident commander that the unit has a 150- to 400-gallon water tank, small pump, limited amount of hose, no ground ladders and a minimum crew of two. Such an apparatus would probably be better used for perimeter patrol, mop-up or attack on fires in light fuels than it would be for assignments involving heavier fuels or structural fire suppression.

Not all states follow the NWCG/ICS type designation system, and some states use a modified or abbreviated version of it. Departments need to be aware of the common wildland apparatus designations used in their area.

In a rapidly shifting wildfire situation, it's sometimes hard to think about apparatus safety. That's bad. Most experienced people will tell you that apparatus safety is doubly important during wildland fires. Here are some tips to keep your personnel and apparatus safe:

Departments should enforce policies that all personnel be seated inside the cab with seatbelts fastened when the apparatus is in motion — both on- and off-road. Riding in an exterior position to attack a running fire is dangerous and doesn't meet NFPA requirements. If a mobile attack is necessary, a remote-control bumper-mounted monitor is the safest method. If a handline is used, the person with the nozzle should walk ahead and to one side of the apparatus in sight of the driver. The nozzle person should watch the fire and terrain and direct the driver with hand signals.

Many wildland apparatus accidents occur when operators drive too fast for the road or terrain. Excessive speed results in excessive side forces during turns and also limits the amount of time the driver has to react to changing situations. Water tenders are especially prone to rollovers caused by excessive speed, and departments should set maximum speed limits for these and other heavy vehicles.

NFPA now requires fine-mesh screens on the engine air intake to prevent embers from igniting the air cleaner filter element. The openings on most punched metal screens are too large to stop embers, so a secondary metal mesh screen may have to be installed.

Smoke and blowing embers can potentially set fire to the interior of the cab. Always keep the windows rolled up, whether the apparatus is moving or parked.

Wildland fire apparatus should always be positioned in the direction of the designated escape route. Trying to turn around on a narrow road or in a driveway wastes valuable time and blocks the route for others.