Brush Up

By Chris Cavette

Light brush trucks are the backbone of wildland firefighting. They are versatile, inexpensive, and can be put into action with a crew of only one or two. Whether departments call them patrol pumpers, grass rigs or any one of half a dozen other names, light brush trucks often can go where larger apparatus can't.

Writing the specifications for light brush trucks might not take as much time as some other apparatus, but departments need to consider several points. Here are some tips to help make your next brush truck safer and more effective.

Attacking a fire in heavy brush with a small pump is dangerous and a waste of time. Likewise, attacking a fire in light grass with a big pump is inefficient and a waste of water. Select a pump with a flowrate appropriate for the vegetation fuel load in your area.

Running out of water after only a few minutes of operation just slows the attack and may give the fire enough time to grow out of control. As a rough rule of thumb, specify a tank with enough capacity to allow at least five minutes of continuous operation at the flowrate selected — 10 minutes would be better.

Overloading the truck with too much water and equipment is unsafe and can break the suspensions or frame rails. Departments need to specify a truck with sufficient payload capacity to handle the expected load. This is especially important when installing new bodies or skid-mount units on trucks that have been obtained second-hand.

Positioning the tank, pump, booster reels and other components low on the chassis helps keep the vehicle center of gravity low for better side stability. It also can improve visibility to the rear and reduce the height of the vehicle for better overhead clearance.

Mounting components low also makes everything easier to reach to help reduce firefighter fatigue. One popular configuration mounts the booster reel at the rear of the body. In this position, the hose can be deployed easily to either side of the truck without getting run over or snagged by the rear tires.

NFPA 1906 applies to light brush trucks and all other wildland fire apparatus. It defines requirements for slip-resistant steps, warning lights, reflective markings and other safety considerations. It also requires that each crew riding position have a seat and seatbelt within a fully enclosed personnel area “that provides total enclosure on all sides, top and bottom, and has positive latching on all access doors”. Sitting or standing anywhere on the exterior of the apparatus is extremely dangerous.

Floodlights at the rear and on both sides of the apparatus can make night operations easier and reduce accidents. Severe service lights with rubber shock mounts can give good life and are designed to run directly off the vehicle electrical system.

Sometimes wildland apparatus need to attack small structure fires. Adding a preconnected 1H-inch attack line can significantly increase the available flowrate to quickly knock down a fire. Keep the hosebed low and easily accessible to allow rapid hose reloading for “bump and run” operations during shifting wildfire conditions.

Most people agree that nozzle-aspirated foam is about twice as effective as water in fighting fires and that compressed air foam is four times as effective. Foam penetrates fuels and coats surfaces to help knock down fires, prevent rekindles and reduce radiant heat exposures. Some gels have the same effect. Most light brush trucks and many skid-mount units can be specified with foam systems.

Departments that want credit from the Insurance Services Office for wildland engines should consider the minimum rating requirements. This is especially important in areas protected by small volunteer stations where the only apparatus is a brush truck.

For ISO's “Minimum Facilities and Practices to Get a PPC Rating” go to www.isomitigation.com/ppc/2000/ppc2002.html.

To view ISO information on “Minimum Criteria for Class 9” (the lowest ISO classification — and the one that usually applies to brush trucks) go to www.isomitigation.com/ppc/2000/ppc2003.html.