Safequip Class A foam very successful as wetting agent for wildfires
Local South African Bureau of Standards (SABS) approved manufacturer and wholesale distributor of firefighting equipment Safequip reports that firefighting foams are still widely used as a firefighting agent, but are underutilised in the South African forestry industry.
Safequip foaming agent specialist Johan Pretorius says that although foams are generally intended to extinguish Class B fires, which are fuelled by flammable or combustible liquids such as oil and gasoline, they are also successfully used as wetting agents for extinguishing Class A fires, which are fuelled by ordinary combustible materials such as wood, paper or cloth.
Pretorius explains that Class A foams were developed for fighting wildfires. Class A foams lower the surface tension of the water, which assists in the wetting and saturation of Class A fuels with water. This aids fire suppression and can prevent re-ignition. Favourable experiences led to its acceptance for fighting other types of Class A fires, including structure fires.
He notes that Safequip’s Aqueous Film Forming Foams (AFFF), which consists of its FCF6UL, FCF3UL and FCF1UL products, have proved to be excellent Class A wetting agents or foams when used in the correct concentrations.
“Our FireChem Class A foam is an ideal product for forest fire extinguishing as it can be applied using non-air aspirating equipment such as airdrop applications done by aircraft.”
Pretorius further explains that experience, as well as tests, have indicated that the addition of a proper wetting agent to water, when properly applied, will increase the extinguishing efficiency of water with respect to quantity used as well as time saved.
Class A foams as wetting agents
Some wetting agents have foaming characteristics as referred to in the National Fire Protection Association (NFPA)-18 standards.
When mixed with water and air, FireChem Class A Foam will produce a foam that retains the wetting and penetrating characteristics of the wetting agent and provides an efficient smothering action to extinguish both Class A and Class B combustibles or provides a fluid insulation for protection against fire exposure.
When mixed with water in the correct proportion, FireChem changes the properties of water. As a wetting agent, it reduces the surface tension of the water and produces foam, which allows the water to cling to vertical or horizontal surfaces without run off. The high surface tension of water causes untreated water to bead-up on the surface of the burning fuel and roll off of the fuel surface without penetrating and absorbing heat or cooling the fire. This problem requires that more water be used to extinguish the fire. The Class A foam solution reduces the tendency of water to bead-up by lowering its surface tension. This allows greater penetration into the burning surface which in turn absorbs more heat and cools the fire much more rapidly, with less water.
Class A foams provide quicker control and increased penetrating power for deep seated fires.
FireChem Class A Foam may be used as a wetting agent, a firefighting foam, or as a fire barrier to pre-treat Class A combustibles. By blanketing a structure that is in the path of a fast moving woodland fire, the foam can actually act as a barrier to prevent the structure from reaching an ignition temperature. This blanket is also capable of preventing airborne embers from igniting the structure.
The foaming properties of Class A foam is dependent on many different factors which include the type of discharge device, the system operating pressure and the amount of foam concentrate in the water.
Advantages and features of FireChem Class A foam:
- Water treated with Class A foam will wet Class A fuels up to 20 times more efficiently than untreated water
- Reduces suppression and mop-up time
- Relatively easy to pre-mix
- Best for use on all types of Class A fires, forest fires and effective Class B Spill Fires
- Can provide a short term fire barrier
- Proportioning and application rates are not critical as with Class B foams
- Raises moisture content in material
- Water treated with Class A foam concentrate is three to five times more effective on Class A fires than untreated water
- Can be used with either fresh or salt water
- Can be used with non-air-aspirating or air-aspirating handline nozzles
- Suitable for use with helicopter Bambi bucket
- Suitable for use with Compressed Air Foam Systems (CAFS)
- Suitable for use on rubber (tires), coal, paper and many other types of Class A fuels
- Suitable for use through medium expansion nozzles on Class A or contained Class B flammable liquids
- Helicopter Bambi Bucket – mix ratio 0.5% to 1%
- Handline, air-aspirating nozzle – mix ratio0.5% to 1%
- Handline, non-air-aspirating nozzle – mix ratio 2% to 3%
- Compressed Air Foam System (CAFS) – mix ratio 2% to 3%
Properties of FireChem Class A Foam as a wetting agent
Application Rate: Three parts of wetting agent to 100 parts of water
Surface Tension: It reduces the surface tension of water from 72 dynes/cm² to less than 33 dynes/cm². This gives great penetrating powder to water.
pH Value: The pH value of wetting agent is between 6.5 to 8.5
Corrosion: It does not have any corrosive properties
FireChem Class A Foam is a 100% biodegradable, non-corrosive, non-toxic firefighting foam concentrate and can be treated in sewage treatment plants.
Fire hoses in a nutshell
Fire hoses that are not properly maintained can deteriorate and eventually burst. Gaskets in female couplings need to be checked and replaced when they are worn or damaged. The hose is the lifeline of a firefighter. When fire fighters respond they rely on the hose to deliver the water to attack the fire and also protect them. Hoses are highly engineered and designed to perform under adverse conditions. Damaged hoses may result in premature and unexpected failure, leaving the fire fighter exposed to the fire.
Most common causes for failure are:
Mechanical: Such as abrasion from being dragged, cuts from sharp objects such as broken windows, particles of grit caught in the fibres, being run over by a vehicle or hose couplings being damaged by dropping them on the ground.
Ultraviolet radiation: From direct sunlight.
Chemicals: Such as battery acid and antifreeze
Heat: By being exposed to the open fire, burning embers and hot coals.
Cold: Where freezing can rupture the liner.
Mildew: Fungus feeds on nutrients in many natural fibres which can cause the fibres to rot and deteriorate.
Safequip offers the Forester hose, which is a percolating hose with a robust, all-synthetic jacket. It is suitable for forest and field firs with the outer coating remaining wet during use. The Forester is rot proof, weather resistant, light and flexible and South African Bureau of Standards 1456 Part 3 approved.