Questions and Answers
What methods do finished foam employ to extinguish or prevent fire? (Select all that apply)
What does separating do in fire extinguishment?
Creates a barrier between the fuel and burning vapors.
What is the purpose of cooling in fire extinguishment?
Lowers the temperature of the fuel and adjacent surfaces.
What does suppressing do in fire extinguishment?
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Through a ________ process, a foam solution creates a finished foam product that forms a smothering blanket over the burning fuel.
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The finished foam blanket excludes ___ and inhibits the burning process.
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The rate at which a foam blanket reduces in effectiveness is proportional to what?
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A good _____ is required to maintain an effective cover over either Class A or Class B fuels.
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What type of bubbles provide long-lasting foam blankets?
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Foam concentrates must match the _____ to which they are applied to be effective.
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What type of foam concentrates will not extinguish polar solvent fires?
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What refers to the increase in volume of a manufactured foam solution when aerated?
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What is the standard for Low-, Medium-, and High- Expansion Foam?
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NFPA 11 states that low-expansion foam has an air/solution ratio up to 20 parts _____ for every part of _____.
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How is medium-expansion foam most commonly used?
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What is the rate for high-expansion foam?
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How long can most modern foam concentrates be stored?
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Class A foam concentrates are mixed in proportions of:
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Most foam nozzles produce more stable finished foams at which percentage concentration?
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Employing percentages greater than ___ percent with standard fog nozzles does not appear to increase fire-fighting performance.
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Exposure protection may be enhanced by applying Class A foam through fog nozzles at ___ percent or greater proportioning settings.
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Fire attack and overhaul with standard fog nozzles requires a foam concentrate of:
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What are needed to produce a foam blanket?
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Foam concentrates are divided into two general categories: those intended for use on Class A fuels and those for use on:
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Foam proportioner is defined as a device that mixes foam concentrate in the proper ratio with:
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Alcohol-resistant AFFF foam may be used in subsurface injection applications on certain light hydrocarbons such as:
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Milspec-listed AFFF concentrates must pass more stringent firefighting tests than UL-listed AFFF concentrates. As a result, milspec-listed concentrates contain more:
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Regular protein foam concentrate is used on all types of fuels.
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What is the mixing of water with foam concentrate to form a foam solution?
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The effect of a surfactant on the water/foam solution allows water to spread more rapidly over the surface of Class A fuels and penetrate organic fuels, referred to as _____ reduction.
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Environmental impact of foam concentrates and foam solution varies. The primary concern is the impact of:
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Study Notes
Foam Concentration and Application
- Class A foam concentrates are mixed in concentrations of 0.1 to 1 percent.
- Stable finished foams are produced more effectively at 1% concentration compared to 0.4-0.5%.
- Concentrations greater than 0.5% do not improve firefighting performance with standard fog nozzles.
- Enhanced exposure protection occurs with Class A foam applied through fog nozzles at settings of 1% or more.
Specific Concentration Guidelines
- Fire attack operations use 0.2 to 0.5 percent foam concentrate.
- Exposure protection operations use 0.5 to 1 percent foam concentrate.
- Most operations with air-aspirating foam nozzles apply 0.3 to 1 percent foam concentrate.
- Compressed-air foam systems generally utilize 0.2 to 0.5 percent foam concentrate.
Foam Types and Properties
- Mechanical foam concentrates are categorized for Class A fuels (ordinary combustibles) and Class B fuels (flammable/comustible liquids).
- Finished foam is created following aeration of a foam solution, which is a mixture of foam concentrate and water.
Properties of Foam and Effectiveness
- Effective foam production requires foam concentrate, water, air, and mechanical aeration.
- Film-forming AFFF concentrates provide superior firefighting properties due to their film-forming and foaming chemicals.
- Regular protein foam concentrates are suitable only for hydrocarbon fuels; they lack fuel resistance.
Temperature and Performance
- Class A foam does not adhere to surfaces exceeding 212°F.
- Most finished foam loses effectiveness when the fuel temperature reaches or exceeds 212°F, breaking down rapidly near 150°F.
Foam Durability and Environmental Considerations
- The life of finished foam is influenced by factors like heat, fuel type, and environmental conditions.
- Foam drainage is affected by fuel temperature and the characteristics of the foam; the rate of drainage impacts overall effectiveness.
Alcohol-Resistant Foams
- Alcohol-resistant foams can produce a membrane over polar solvents, enhancing effectiveness against hydrocarbon fuels.
- Alcohol-resistant AFFF can be gently applied to form a membrane over polar fuels, avoiding aggressive plunging of foam.
Applications and Challenges
- High-expansion foams are suitable for confined spaces and specific industrial uses; outdoor use is often not recommended due to environmental factors.
- Vapor mitigation foam concentrates work on unignited spills; they are less effective in direct firefighting situations.
Critical Firefighting Techniques
- Finished foam extinguishes fires through separation, cooling, and suppressing methods:
- Separating creates a barrier between fuel and vapors.
- Cooling lowers the temperature of fuel and surfaces.
- Suppressing prevents additional flammable vapors from igniting.
Future Developments and Research
- Ongoing advancements in foam technology, such as AR-AFFF, are designed to combat acidic or alkaline reactions while maintaining performance in various conditions.
Key Takeaways on Foam Concentrate Use
- Selecting appropriate foam concentrates requires consideration of the type of fuel and the intended application.
- Effective firefighting performance is contingent on proper mixing ratios, environmental factors, and foam properties.### Foam Expansion
- Foam expansion refers to the process where a foam solution expands by incorporating air, creating a foam that can effectively suppress fires.
NFPA 11 Overview
- The National Fire Protection Association (NFPA) published NFPA 11, a standard that outlines requirements for Low-, Medium-, and High-Expansion Foam in 2002.
Low-Expansion Foam
- Low-expansion foam features an air/solution ratio of up to 20:1, meaning for every part of foam solution, up to 20 parts air are introduced.
Medium-Expansion Foam
- Medium-expansion foam is most commonly deployed at an air/solution ratio ranging from 20:1 to 200:1, primarily utilizing hydraulically operated nozzle-style delivery devices for application.
High-Expansion Foam
- High-expansion foam can achieve an air/solution ratio between 200:1 and 1,000:1, allowing for extensive coverage in large volumes.
Storage Durability
- Modern foam concentrates are designed for long-term storage, with a shelf life exceeding 10 years, ensuring reliability in emergency situations.
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Description
Test your knowledge on the methods of fire extinguishing foam. This quiz covers key concepts such as separating, cooling, and suppressing to understand how they work to extinguish or prevent fires. Challenge yourself and see how well you know these techniques!
