Why Class A is a cut above: there will always be financial reservations about investing in relatively new developments, but the author suggests that new technology has made Class A foam application easy, accurate and more cost-effective than ever before - Ancillary Equipment - Compressed Air Foam Systems

Class A Foam and Compressed Air Foam Systems (CAFS) are attracting increasing interest as a more efficient and environmentally safe method of fighting most types of combustible material fires including structural fires. Testing CAFS equipment to assess the key benefits of using Class A foam with CAFS equipment shows:

* Quicker knockdown times of fires;

* Quicker reduction of heat--cooler environment;

* Less water needed--massive reduction of water damage;

* Reduced environmental damage;

* Firefighters exposed to fewer firefighting hazards;

* Simple to use--no special training required; and

* Reduction in firefighter fatigue due to reduced suppression time and effort.

Class A foam concentrate, available in either 19 litre or 208 litre containers, is made to be diluted with water and applied on ordinary combustible fuels. Originally used for forest fires, it was developed in Canada during the early 1980s. After its introduction, forest firefighters found exposure protection applications for the product on homes situated in the wildland/urban interface. Trial and error testing by fire instructors also indicated that it worked well for direct fire attack on materials round in structural firefighting, including deep-seated hay bales, coal silos and vehicle tyres.

It is classified as a synthetic detergent hydrocarbon surfactant and is similar to a triple strength dish detergent. Its components reduce high surface tension to make water penetrate the crevices found on fuel surfaces. It also contains foaming agents that create bubbles when the foam solution is agitated with air. These keep the water contained within them in contact with vertical surfaces to provide efficient fuel cooling. Class A foam clings to fuels instead of rolling off, preventing the fireground water waste associated with conventional water fire streams.

US FIREFIGHTERS TRAINING WITH CAFS

The foam works well when applied on burning synthetic fuels associated with interior furnishings and finishes (such as foam chair padding), which are hydrocarbon based, giving off much higher rates of heat release and burn at higher temperatures than their non-synthetic counterparts.

Flammable gases distilling from these synthetic materials increase flashover potential for firefighters. The benefit for initial attack teams is that Class A foam provides the extra punch needed to knockdown and secure high-challenge synthetic burning materials.

It is possible decision makers perceive Class A foam concentrate to be expensive and difficult to mix and apply. There may be assumptions that it is similar to Class B (flammable liquid) foam or that CAFS equipment is too expensive and unecessary. However, the initial expense of acquiring foam concentrate, loam hardware and brigade training must be weighed against the benefits they provide. Class A foam and CAFS technology make good economic sense, because it reduces property damage and increases firefighter safety.

The most effective delivery system available today to generate Class A foam is a CAFS. A fire appliance equipped with CAFS equipment contains a high-volume air compressor (1560 cubic metres per minute) integrated with a foam proportioning system and the normal centrifugal fire pump.

HALE MINICAFS UNIT RETROFITTED TO A UK FIRE APPLIANCE

In a CAFS unit, compressed air is injected into foam solution in the apparatus piping, before discharge into the hoseline. Finished foam is discharged into the fire hose or fixed master stream appliance. The advantages of using CAFS, rather than standard branches and foam nozzles to generate finished-foam include:

* Higher quality finished-foam production;

* Lightweight hose lines;

* Increased fire stream discharge distance; and

* Finished-foam consistencies that range from `milky wet' to `shaving cream' dry. The benefits for the fire officer are:

* Increased flame knockdown capability from a limited water supply;

* Better exposure protection;

* Less fatigue from lightweight CAFS hoses (hoselines are filled with a partial volume of air); and

* Increased foam stream penetration to reach the core of the fire.

CAFS equipment is available in a number of different configurations. These range from the Mini-CAFS, a self-contained retro-fittable unit for the compartment of an existing vehicle (typically a small appliance), to the World Series vehicle pump with an integrated CAFS module built-in. There is also a range of engineered packages that the vehicle builder can integrate into the design according to customer requirements such as CAFS90/200.

The potential of CAFS used with Class A foam offers the ability to deliver large quantities of agent over long distances with the absolute minimum manpower to attack structural fires that previously required massive tactical operations.

Either initial attack time should be reduced on most fires, or sustained combat time should be much shorter, with less overhaul and mop-up times for all fires. Implementing CAFS can significantly improve fire suppression capability.

Further information on CAFS equipment is available from Hale Products Europe on tel: +44 (0)1926 623600; fax: +44 1926 623666. info@haleeurope.com or www.haleeurope.com

David Burton is Marketing Manager, Hale Products Europe.

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