Gel technology is becoming more recognized and used in firefighting, and some believe that gels will replace foam as a water enhancer. Foam and gel manufacturers will say that their product is better than the other and better than competitors. It is important that they believe in their product. But it is even more important that these people understand the limitations of their product and the technology.

In its simplest form, foam concentrate is mixed with water to form air bubbles. These bubbles help cool and smother fires. The surfactant in foam concentrates help break down the surface tension of water. This helps it penetrate the charred material and lets the foam cool the material, eventually put the fire out. Foam also is used on wildland fires when a wet line is needed; foam gives the wet line a much longer hang time on the vegetation than does straight water. This allows for more wet line to be placed in a shorter time.

CAFS let firefighters stretch water resources even more than simple foam. Introducing compressed air into the foam- and water-mixture produces a very thick and light blanket of foam with a greater cooling ability than regular water or low-, medium- or high-expansion foams. CAFS is fast becoming a regular fixture on Type-1 engines in most cities, and the crews are using it for interior attack on structure fires with great results. This requires specific training, but a skilled crew can extinguish a room-and-contents fire just as quickly as before using a fraction of the water.

It is important to remember that Class A foam is designed for Class A fires and Class B foam is designed for Class B fires; the two are not interchangeable. Foam is a great tool for extinguishing fires and protecting vegetation. But there is no wonder tool that does everything. And foam or CAFS have too many limitations that make it unconducive for exposure protection.

Gels come in two types: liquid concentrate and powder. The biggest difference is that the liquid concentrate is educted into the water stream and the powder is batch mixed and pumped through a hose.

Gels are made up of four basic components: water, super-absorbent polymers, a surfactant, and either a mineral oil or a vegetable oil. The concentrate is mixed and then inducted into the water stream. The gel encapsulates water, absorbs heat and sticks to most every surface that would need fire protection. Once the gel has been applied to a surface, warm temperatures and high winds make it evaporate. Misting the dried product with water using a 30% fog pattern will reverse evaporation.

In 1998, gel was first used on an uncontrolled fire in northern Alberta, Canada, and put Barricade Fire Blocking Gel on the map by saving a $60 million pulp and paper mill during a wildfire. Since then, gels have been used to extinguish tire fires with amazing results and very little cleanup. They were originally intended to be an exposure-protection tool. Using gel, one engine crew can pre-treat a structure in 30 minutes with very little water and get up to 24 hours of protection. Homeowners can even spray the gel onto their homes with a garden hose then evacuate to safety. Gel also works in aerial operations on wildfires.

There is no gel that can be used effectively with salt water. Use caution with gel concentrate containing mineral oil, as it will soften petroleum-based product such as asphalt and composite shingle.

There will be a home for both foam and gel in the firefighter toolbox. It is very important to train firefighters to understand how the two different tools should be used and to use them for their intended purpose.

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Darren Hutchinson is president and COO of Quintech Fire Services Ltd.

The 2008 Focus on Foam is sponsored by: