However water by itself is not recommended for use on

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Aqueous Film-Forming Foam (AFFF). However, water by itself is not recommended for use on class B fires. Class C of Fire Class C fires are energized electrical fires that are attacked at prescribed distances by using nonconductive agents such as CO 2 and Halon 1211. The most effective tactic is to de-energize the system and handle the fire as a class A fire. When fires are not deep seated, clean agents that pose no cleanup problem, such as Halon 1211 or CO 2 , are the preferred extinguishing agents. However, water in any form, is dangerous when used on electrical equipment. (c) UPES, Not for Reproduction/ Sale
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UNIT 7: Aircraft Rescue and Fire Fighting Services Notes ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ Class D of Fire Class D fires are combustible metals, such as magnesium and titanium. Water in large quantities, as high velocity fog, is the recommended extinguishing agent. When water is applied to burning class D materials, there may be small explosions. The fire fighter should apply water from a safe distance or from behind shelter. Extinguishing Agents There are many materials that may be used as fire-fighting agents. The primary agents discussed in the following paragraphs are the most extensively used. Water Water is a cooling agent, and it is easily available. If the surface temperature of a fire can be lowered below the fuel's ignition temperature, the fire would be extinguished. Water is most efficient when it absorbs enough heat to raise its temperature to 100°C or boiling point. The steam carries away the heat, which cools the surface temperature. Water in the form of fog is very effective for fire-fighting purposes. Additionally, water fog can provide protection to fire fighters from heat. However, the fog must be applied directly to the area to be cooled if its benefits are to be realized. Water in the form of a straight stream (also called solid stream) is used to reach into smoke-filled spaces or areas at a distance from the fire fighter. When a straight stream is needed as an extinguishing agent, it should be directed into the seat of the fire. For maximum cooling, the water must come in direct contact with the burning material. A straight stream is best used to break up and penetrate materials. Aqueous Film-Forming Foam (AFFF) AFFF is composed of synthetically produced materials similar to liquid detergents. These film-forming agents are capable of forming water solution films on the surface of flammable liquids. AFFF concentrate is non-toxic and biodegradable in diluted form. When proportioned with water, AFFF provides three fire- extinguishing advantages. (c) UPES, Not for Reproduction/ Sale
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Notes ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ Aviation Safety & Security Management 1. An aqueous film is formed on the surface of the fuel that prevents the escape of the fuel vapours. 2. The layer effectively excludes oxygen from the fuel surface.
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  • Fall '19
  • Instrument approach, Runway, Rajiv, Aviation Safety & Security Management

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