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First-due fire chiefs and company officers often face the serious problem of advanced fires spreading to exposed buildings and combustibles.
Photo sequence shows two wood panels being ignited. The panel at left is unprotected and the one at right is covered with the fire-blocking gel.
Traditional wisdom has abandoned the old water-curtain theory of spraying water between the burning structure and the exposures in danger. A more effective method is to flow water directly onto the surface of the area to be protected. Putting the water on the surface allows it to absorb conducted heat (what the radiant heat turns into when it strikes a solid object). It also protects against direct flame impingement, thereby reducing the effects of the two most common causes of flame spread.
Even this relatively effective method has a down side: it requires manpower at the scene and a good water supply. A manned line will have to be operated onto the structure until the source of the threat has been removed. Most fire officers don't have the luxury of unlimited water and people able to deliver it where it is needed.
With these problems and the possible solution in mind, two Palm Beach, FL, firefighters, Bill and John Bartlett, approached chemists Gerry and Joe Stickl to determine whether a plan they had was feasible. As with most good ideas it is relatively simple.
Using superabsorbent polymer technology and standard fire department equipment, they offered a new product that can be used to protect exposures. The new product is drawn up through standard AFFF-type foam eductors and introduced into the water stream. The superabsorbent particles absorb water (hundreds of times their own weight) in a chemical-physical process called hydration. The resulting viscous solution is a superabsorbent polymer liquid that will be marketed under the trade name Barricade. This fire-blocking gel is essentially a protective coating that can be sprayed onto walls, roofs, brush, shrubbery or any other Class A combustible material. The gel can be quickly sprayed onto structures, compressed gas cylinders, railroad tank cars and motor vehicles to protect them from radiant heat and direct flame impingement.
The reason this viscous solution works is that the millions of tiny superabsorbent particles become filled water and are stacked one on top of the other. This is similar to the stacking effect of AFFF and Class A foams. The big difference between the two is that the gel's "bubblets" are filled with water while the foam bubbles are filled with air. The stacked, water-filled "bubblets" dramatically enhance the thermal protective properties of the new product offers. It also has adhesion characteristics that allow it to be sprayed onto horizontal and vertical surfaces such as walls, roofs, ceilings, overhangs and windows.
In the case of an urban interface fire, threatened buildings and structures as well as trees and shrubs can be pre-treated with the gel well in advance of an approaching fire. Forestry units will also be able to utilize its coating ability to create fire -breaks without damage to the landscape and without the soil disturbance caused by plows and other machinery.
John Bartlett said he believes the product is well suited for use in large-scale "surround-and-drown" fires. Such situations often require large amounts of time and resources because only a small portion of the water being pumped into the burning structure actually reaches the seat of the fire. Most of the water turns to steam in the superheated air above the fire and is carried away with the smoke and rising gases. The binding properties of the fire-blocking gel slows the evaporation process allowing more of the product to make it through to the hot air to the seat of the fire.
For further information about the gel, contact John Bartlett at Fire Protection Inc., P.O. Box 4506, Tequesta, FL 33469. The telephone number is 407-744-0204; fax 407-747-4471.