Basic Forest Fire Suppression Course - Online Lessons


4.5 Class "A" Foam

Class A foam was introduced to wildland fire fighting with the intent of using it to quickly and effectively suppress fire. It is a surfactant (Surface Acting Agent) that has the capability of reducing the surface tension of water and increasing it`s effectiveness from 3 to 10 times more than water used alone. The product is versatile and is not strictly limited to either initial attack or mop up, it can be used during both phases of the operation. During initial attack, foam can be used to contain forward progress around the fire perimeter, or in more extreme conditions can be applied directly to values that need protection. Foam application during mop up is most effective when there is limited water supply, or ground conditions are dry.

The characteristics of foam provide it with the ability to stick to fuels and completely surround them. The results provide the following suppression advantageous:

  1. Smothers oxygen supply around fuels. Because foam completely surrounds burning material, the oxygen supply required for the combustion is inhibited and could cause the process to stop.

  2. Isolates fuels sources (burning materials pre - heating other unburned fuels nearby) by removing heat from the surrounding unburned fuels. Accomplished by completely surrounding burning material.

  3. Insulates by completely surrounding fuels and separating them from fire.

The foam induction system (Blizzard Wizard) used by N.S. Department of Natural Resources has been added to pumping system of it`s fleet of fire trucks to provide additional suppression capabilities. The same system can be taken off the truck and used on any Wajax Mk 3 around the fire line. Because foam solution is a degreaser (can remove grease from a metal surface) it must be kept away from the internal mechanism of a working pump.

Once set up, foam is produced using the following procedure: The solution is siphoned from a container into the inductor, and then added to the water supply that has been discharged from the pump into the forestry hose (1.5 inch hose) Water and solution are aerated at the end of the forestry hose producing foam concentrate. After use, all pieces of equipment that come in contact with foam solution should be throughly flushed with clean warm water to prevent corrosion.


  1. Avoid contact with eyes. Eye protection must be worn. Flush eyes immediately if contact is made.

  2. Avoid contact with skin. Wear gloves when using. Wash throughly if contact is made and apply moisture to affected area.

  3. Avoid inhaling. Avoid working in confined area. Vapors could cause breathing problems for some.

  4. Avoid contact with leather boots. Foam will draw moisture from boots and could cause leather to crack.

  5. Exercise caution when handling near water. Secure solution container with a stable base or tie the container to a secure object (tree). Confine spill and begin clean up procedures, if necessary. Spills need to be reported to the Safety Officer or IC.

This completes Lesson 4 - Forest Fire Suppression Tools

Proceed to the Quiz 4