15 June 2001

For information contact: Lynn Solorio, Community Relations Coordinator, Carus Chemical Company, phone: 815/224-6682; e-mail:

Fighting fire with fire . . . and ping-pong balls?

Using fire as a tool to manage the environment is nothing new. Native Americans used fire to control the trees and grasses long before the white man settled in North America.

Evidence suggests that less than 200 years ago, vegetation was very different from what it is today. In many areas of the country, pine trees grew to be three feet in diameter and over 100 feet tall. The ground below these pines was covered with native grasses. Completely missing from the landscape were the briars, brambles, and brush we see on a walk through the woods today. In the past, the pine above and the grass below was maintained by frequent, naturally occurring wildfires. Fire was also often "encouraged" by Native Americans.

The primary reason why the woods of today are so different from the woods of the past is the lack of fire in the environment today. For years we worked hard to fight forest fires, not appreciating the role fire plays in the delicate ecological balance of the planet. Experts today recognize fire as an element necessary to sustain our environment.

Fire, and the means of harnessing and managing it, is state-of-the-art. It has truly developed into a science, and scientists are using chemistry to control fire.

Forest fires: wild vs. "prescribed"

In the United States, fire is used extensively as a tool to manage the national forest and range lands. Kevin Hamilton of Boise, Idaho, Aviation Specialist for the Federal Bureau of Land Management, acts as an advisor to the firefighter professionals who work with "prescribed burning" -- defined as using fire to reach an objective. This is in direct contrast to "wildfires," which occur either naturally (lightning strikes) or are man-made (careless smoking or misuse of other ignition materials). Some of the same firefighting techniques, most of which involve chemicals, are used in both wildfire control and prescribed burning.

Though any incidence of fire in a park or forest would seem catastrophic to the layman, park rangers often intentionally start and carefully monitor small fires that offer specific benefits to wildlife and the forests themselves. Strangely enough, one reason for conducting a prescribed burn on a given area is to improve the taste and nutrition of plants used as food by wildlife. Prescribed fire also reduces the amount of fuels that could be consumed by a wildfire, thereby reducing hazards to wildlife and vegetation. Fire is often necessary to provide a natural seedbed for pine trees, and it encourages sprouting by hardwoods such as oak, thus renewing the forest. According to Hamilton, prescribed burning is used both to backlight wildfires and to reduce fuel; in other words, specialists start fires to deliberately burn the debris on the woodland floor that might otherwise fuel an uncontrolled, forest-destroying blaze.

Fighting fire with fire

A prescribed or controlled burn is planned only when the most favorable, precise climate and environmental conditions exist. The time of year, relative humidity, air mass stability, temperature, fuels, wind speed and direction, all must be precisely right if a prescribed burn is to be considered. A well-equipped and extensively trained fire fighting force must supervise the fire. Flame height is carefully controlled, as is the rate of spread and the total area burned.

The best-known (and most old-fashioned) firefighting technique is to simply douse the flames with water. However, water is not the only, or necessarily the best, way to control fire. As firefighting has developed into a science, the techniques and equipment utilized are continually upgraded and modernized to keep pace with technology and the needs of the environment.

Using the science of chemistry to control fire

In one technique, firefighters use foam to blanket the flames and reduce combustion. This method is not always effective as it relies on moisture and so, like water, it is a short-term solution.

In order to contain a rapidly spreading fire, firefighters in forests and parks often light backfires, intentionally setting fire to whatever might burn inside a control line to create a barrier between the fire and the line.

Fire retardants (defined as any substance except plain water that, by chemical or physical action, reduces the flammability of fuels or slows their rate of combustion) are also used to control wildfires. These substances, in either liquid or slurry form, can be applied aerially or from the ground.

Another aerial fire control technique uses a helitorch, a giant drip torch and drum of gelled gasoline slung under a helicopter. This system emits a steady stream of burning globs of fuel. A drawback to this method is that it is very difficult to effectively regulate the spacing between these fuel globs.

One controlled burn technique gaining popularity among park rangers and fire specialists across the U.S. is the Delayed Aerial Ignition Device or DAID (the process o f dropping or dispensing an igniting device or material from an aircraft). Forest service managers, park rangers, firefighters, and helicopter pilots commonly refer to this tactic as "the ping-pong ball method."

What do ping-pong balls have to do with firefighting?

Heres how the ping-pong ball drop method works: On board a helicopter, a trained fire specialist is operating a device packed with small plastic spheres filled with a precise amount of potassium permanganate, an inorganic chemical oxidant. The little plastic spheres are about the size and shape of ping-pong balls, thus the name. An arm of the machine holds each ball and injects it with a measured quantity of ethylene glycol, and the ball is rolled down a chute and immediately jettisoned from the helicopter. Within 30 seconds, the chemicals in the ball react thermally to produce a small fire. As the ball hits the forest floor and bursts into flame, it produces the required fire at the exact

location where it is needed. The plastic ball and its contents are completely consumed by this burning. The end result is a spot of fire that, when multiplied by the number of balls dropped, enables forest service managers to ignite areas of land quickly and safely.

According to the Private Forest Management Team at Auburn University, the ping-pong ball operation is very safe and cost effective. Aerial ignition dramatically reduces the time needed for an area to burn out. The smoke produced is emitted over a shorter period of time and more of it is drawn in an upward column, thereby reducing the impact of any adverse effects on air quality. Aerial drops are particularly effective for fire control work in inaccessible areas. The method also provides a no-hands (and therefore safer) means of starting fires to burn debris.

Although the ping-pong balls are most commonly dropped from helicopters and small airplanes, one company is looking into the possibility of developing machinery that, stationed on the ground, can actually lob the balls into a fire.

The ping-pong ball method is used widely in the United States. Eddie Morris, Helicopter Program Manager for the Atlanta office of the U.S. Forest Service, explains that the machinery used is in such demand that rangers and firefighters in the U.S. Forest Service, the U.S. Park Service, and the Bureau of Indian Affairs are often required to share the fire control equipment. And according to Lewis Puckett, President of Aerostat, Inc., the U.S. distributor of the potassium permanganate-filled spheres (i.e., ping-pong balls) and the machinery that drops the balls out of helicopters, " We probably have 300 machines out there, and we cant keep up with the demand for the darned things."

America is not the only country where firefighters are taking this proactive approach to fire control. A state forester in Australia, Anthony Signor, said the use of aerial and ground hazard reduction burning programs, including back burning using the ping-pong ball method, has increased significantly in Australia in recent years. Signor said that the program, combined with the backup of a well-equipped and trained fire fighting force, "helped prevent wholesale bushfire damage to vegetation and ground cover."

Carus Chemical Company, headquartered in LaSalle-Peru, Illinois, is the worlds leading manufacturer of potassium permanganate. Carus manufactures potassium permanganate mainly for environmental applications: to improve the quality of drinking water, to treat municipal and industrial wastewater, in air purification systems, and in the remediation (clean-up) of contaminated sites. Although not presently involved in the production of the potassium permanganate-filled "ping-pong balls," Carus is interested in supporting the scientific knowledge of how to use chemistry to improve firefighting techniques.

Carus Chemical is a member of the American Chemistry Council and is an active participant in the industrys award-winning Responsible Care® initiative, working to make life better, healthier, and safer through chemistry.

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