Frequently Asked Questions about CAFS

What is compressed-air-foam?

Compressed Air Foam applied on a tree

Compressed-air-foam is the result of injecting nitrogen (or air) into a solution of water and foam concentrate. The foam concentrate has been specifically developed for class A type fuels found in the Wildland/Urban Interface (WUI) and has an expansion rate that allows water, in the form of bubbles, to be used more effectively. One gallon of water can be expanded nearly 20 times as foam and unlike water, foam clings to a structure and the surrounding fuels. Foam is used extensively by wildland fire management agencies for both suppression and pre-suppression activities in the WUI.

How does Class A foam protect my home from fire?

Foam from a FFD CAF system is applied in advance of an oncoming wildfire. The tightly packed bubbles within the foam adhere to your home's surfaces and surrounding vegetation, gradually releasing the moisture they contain. The bubble's structure both absorbs and reflects heat up to 5 times more efficiently than plain water. It also provides a barrier to oxygen, necessary to sustain combustion. The surfactants and organic carbon molecules contained in the foam solution allow for the slow release of water to penetrate the fuels onto which it is applied such as trees and shrubs around your home. The bubble mass also provides a protective barrier for unburned fuels and fuel complexes which are difficult to keep wet and isolated from heat and flying embers such as brush, the under side of patio decks and air vents on roofs.

Why is FFD compressed-air-foam better than aspirated type foam?

Compressed air foam is 4 to 5 times more effective than water in cooling heat and extinguishing fire because of the structure of the bubbles.  Aspirated foam has a wet and frothy structure and is only twice as effective as water--not significantly better. Aspirated foam is generated by a special nozzle and expands less than compressed-air-foam using the same foam solution. Aspirated foam applications are popular with professional firefighters who need a wet frothy foam for immediate results when fighting fire. The FFD generated foam is tailored for protecting (pre-suppression) in advance of an oncoming fire. Compressed-air-foam is much lighter (expanded more) with the same volume of water and gives you longer protection because it runs off surfaces more slowly.

What about foam concentrate attachments for my garden hose?

Foam concentrate attachments for garden hose application connected to your home's main water supply have many drawbacks. If you are on well water, power failures, frequent during a wildfire, could leave your electric pump idle leaving you with no fire protection. Water pressure on municipal systems can drop significantly during a wildfire as well caused by a sudden increase in demand from other fire fighting activities.  Low water pressure will greatly affect the performance of any system driven from a garden hose.  Finally, if the bubble structure of the garden hose delivered foam is not tightly packed, the applied foam may run off of targeted surfaces more rapidly providing a shorter duration of protection and very possibly a poorer level of protection at any time.

What properties of foam does FFD consider?

FFD believes that the following foam properties are most important in providing pre-suppression and suppression fire protection: expansion, density, drain time and surface tension. Expansion ratios are divided into 3 categories relating to how much foam is generated. FFD systems are low expansion systems and generate nearly a 20:1 expansion rate.The foam's densely packed bubble structure has a drain time of nearly 1 hour under ideal conditions. The surface tension of water is quite high. The surfactants in Class-A foam concentrate reduce that surface tension more than 50%, allowing for greater penetration of smaller water particles that penetrate both live and dead fuels.

How difficult is a Foam Fire Defense system to use?

An FFD system is simple to use. There is little time to think when wildfire occurs so we've designed the system to require no special training, Like washing your car, you roll out the FFD hose with the spray nozzle in the off position to prevent it from snaking around. Then you open the valve at the unit, return to the nozzle, open it, and spray down your home. That's how simple the FFD system is. Our hose is larger in diameter than a garden hose (1-1/2 ") and the full bore nozzle has a pistol grip for operator comfort and control. The pressure at the nozzle end is greater than an average garden hose, so when opening the main valve, do so slowly and with a firm grip. It's that simple.

How long does the foam last once it's been applied?

Foam dispensed by a FFD system will usually be visible for approximately an hour. Foam, however, contains a large volume of water, which seeps slowly into the surfaces and fuels it is applied to. Hot temperatures and windy conditions affect the stability of foam which is normally applied about 3 inches thick on roofs and any horizontal surface. In-house tests have shown a 1-1/2 inch thick layer of foam on an asphalt roof with a surface temperature of 98 degrees lasted approximately 55 minutes, after which there was no foam visible on the target surface, but the asphalt shingles were saturated with water. Consequently, the heat absorption potential of the foam-treated shingles was increased.

There is a protein foam variant that is extremely durable but stains whatever it's applied to. This durable foam can last 24 hours or more. The structure owner must realize that this stain requires professional cleaning and quite possibly a new paint job. 

What kind of foam concentrate is used with the Foam Fire Defense system?

Phos-Chek WD881 is specified to be used in the FFD system. This foam concentrate has been tested and meets all the requirements of NFPA 1150. It is also certified by the USDA Forest Service. It is considered a Class A foam concentrate that is readily biodegradable with no flash-point and is used on wildland fires around the world.