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Why buy a compressed air foam system for class A application?
Class A foam enhances the effectivity of water by 300 percent
C
ompressed air foam systems (CAFS) have been used internationally for many years and there are a number of world class fire fighting vehicles operating in South Africa that are fitted with CAFS , so CAFS are not new to South Africa. However, many departments are still to discover the effectivity and operational soundness in adding CAFS to their fire fighting toolbox. What comprises a CAF system? CAFS consists primarily of the following components, either fitted directly to the onboard pump or on a transportable pumping system: 1. Water – from the tank, open source, portable dam or hydrant 2. Foam concentrate – from a foam tank or an external source 3. Fire pump, vehicle mounted or portable 4. Induction system to measure and introduce the correct volume of foam concentrate to water 5. Air compressor Note: There are a number of portable single load CAF systems available on the market but, for the sake of this article, we are addressing the CAFS fitted to a vehicle and that offers sustainable operations. How do CAF systems work? CAFS work by operationally combining all the above noted components. Water is pressurised through the pump, foam is injected in the water stream and air is added to the foam solution in order to generate finished foam. By introducing air into the foam solution, a stable foam structure is produced that is more durable and is capable of absorbing the caloric output of the fire.
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Furthermore, because of the addition of air, the foam quality can be selected from wet (0,2 percent induction for overhaul); fluid (0,5 percent for initial attack) and dry (1,0 percent for exposure protection).
Why CAFS? The technical reasons why CAFS are so effective is best demonstrated live, following a classroom theory introduction. Fire Raiders would welcome the opportunity to visit your department for in-depth presentations that finitely show how and why CAFS work and work so effectively. For the sake of this article, we will only cover the very basics of CAFS. Although water remains the primary choice for the fire service to suppress fires, there are many factors that you might want to consider when deciding to use only water for your suppression efforts. The limiting factors of using water independently are, amongst others: • Water has a high surface tension thus preventing penetration Volume 3 | No 12