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NFPA 11: Standard for Low-, Medium-, and High-Expansion Foam
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What is NFPA 11?
NFPA 11: Document Scope

1.1* Scope. A.1.1 Fire-fighting foam is an aggregate of air-filled bubbles formed from aqueous solutions and is lower in density than flammable liquids. It is used principally to form a cohesive floating blanket on flammable and combustible liquids and prevents or extinguishes fire by excluding air and cooling the fuel. It also prevents reignition by suppressing formation of flammable vapors. It has the property of adhering to surfaces, which provides a degree of exposure protection from adjacent fires. Foam can be used as a fire prevention, control, or extinguishing agent for flammable liquid hazards. Foam for these hazards can be supplied by fixed piped systems or portable foam-generating systems. Foam can be applied through foam discharge outlets, which allow it to fall gently on the surface of the burning fuel. Foam can also be applied by portable hose streams using foam nozzles or large-capacity monitor nozzles or subsurface injection systems. Foam can be supplied by overhead piped systems for protection of hazardous occupancies associated with potential flammable liquid spills in the proximity of high-value equipment or for protection of large areas. The foam used for flammable liquid spills is in the form of a spray or dense “snowstorm.” The foam particles coalesce on the surface of the burning fuel after falling from the overhead foam outlets, which are spaced to cover the entire area at a uniform density. (For systems required to meet both foam and water spray design criteria, see NFPA 16.) Large-spill flammable liquid fires can be fought with mobile equipment, such as an aircraft crash truck or industrial foam truck equipped with agent and equipment capable of generating large volumes of foam at high rates. Foam for this type of hazard can be delivered as a solid stream or in a dispersed pattern. Standards for industrial foam trucks include NFPA 1901, and standards for aircraft crash trucks include NFPA 414. Foam does not break down readily and, when applied at an adequate rate, has the ability to extinguish fire progressively. As application continues, foam flows easily across the burning surface in the form of a tight blanket, preventing reignition on the surfaces already extinguished. Foam is not suitable for three-dimensional flowing liquid fuel fires or for gas fires. To determine where foam protection is required, see applicable standards such as NFPA 30. Foam can be applied to protect the surface of a flammable liquid that is not burning. The foam concentrate manufacturer should be consulted to determine the optimum method of application, rate of discharge, application density, and frequency of reapplication required to establish and maintain the integrity of the foam blanket. 1.1.1 This standard covers the design, installation, operation, testing, and maintenance of low-, medium-, and high-expansion and compressed air foam systems for fire protection. 1.1.2 It is not the intent of this standard to specify where foam protection is required.

This standard covers the design, installation, operation, testing, and maintenance of low-, medium-, and high-expansion foam systems for fire protection. Criteria apply to fixed, semi-fixed, or portable systems for interior and exterior hazards.

Official document scope
What does NFPA 11 address?

General requirements include system components and system types, specifications and plan installation, testing and acceptance, and maintenance. Separate chapters address specific issues associated with low-expansion system design, medium- and high-expansion systems, compressed air foam systems, and low-expansion foam systems for marine applications.

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