What is necessary when applying fire fighting foam – Full Guide

Firefighting foam is a crucial tool in modern fire suppression strategies, employed to effectively combat and control various types of fires. However, What is necessary when applying fire fighting foam? This article will reveal considerations and techniques involved in the application of firefighting foam.

The application of firefighting foam requires careful consideration of several key factors, including the type of foam, the nature of the fire, and the specific firefighting objectives

So when applying firefighting foam, it is crucial to consider factors such as selecting the appropriate foam type, maintaining the correct proportion of foam concentrate and water, calibrating equipment for optimal performance, employing suitable application techniques based on the fire and foam type, being mindful of environmental impacts, prioritizing safety measures with proper personal protective equipment, and ensuring the responsible disposal of foam concentrates and wastewater to minimize adverse effects.

Additionally, understanding the specific fire class, whether it be A, B, or C, guides the choice of foam formulation for effective suppression. The calibration of firefighting equipment, including nozzles and applicators, is essential to deliver foam at the recommended flow rate and expansion ratio, ensuring comprehensive coverage of the fire. 

Firefighters must undergo training to master the application techniques that vary according to the fire scenario, whether it involves gently applying foam for liquid fuel fires or employing high-expansion foam in confined spaces.

Importance of Proper Application Fire Fighting Foam

Importance of Proper Application Fire Fighting Foam

Firefighting foam is a critical component in the arsenal of tools used to combat various types of fires. Its effectiveness lies in its ability to suppress and extinguish fires by forming a protective barrier, cutting off the oxygen supply, and cooling the fuel source. 

Proper application of firefighting foam is essential to maximize its efficiency and ensure the safety of both firefighting personnel and the surrounding environment.

Here are the importance of proper application of Firefighting foam:

1. Fire Suppression and Extinguishment:

Properly applied firefighting foam creates a cohesive blanket that suppresses the release of flammable vapors and smothers the fire, leading to effective extinguishment. This is particularly crucial in combating flammable liquid fires, such as those involving fuels and chemicals.

2. Oxygen Exclusion:

Firefighting foam acts as a barrier, preventing the entry of oxygen into the fire. By depriving the fire of this essential element, foam helps break the fire triangle and disrupts the combustion process, aiding in quicker and more efficient suppression.

3. Cooling Effect:

Firefighting foam has a cooling effect on the fuel source, reducing the temperature and preventing re-ignition. This is especially beneficial in incidents involving Class A fires (ordinary combustibles) where the cooling effect helps in preventing the fire from spreading.

4. Protection of Personnel:

The correct application of foam enhances the safety of firefighting personnel by providing a barrier between them and the hazardous conditions. It reduces the risk of flashovers and backdrafts, allowing firefighters to operate more effectively in challenging and dangerous environments.

5. Environmental Protection:

Using the appropriate firefighting foam and applying it correctly minimizes the environmental impact of fire incidents. By preventing the spread of hazardous materials and runoff contamination, proper foam application contributes to environmental conservation and protection.

6. Equipment and Infrastructure Protection:

Foam can be instrumental in protecting critical equipment and infrastructure from fire damage. By forming a protective layer, it prevents the fire from reaching sensitive equipment and minimizes the risk of collateral damage.

7. Versatility Across Fire Classes:

Firefighting foam is versatile and effective across various fire classes, including Class A (ordinary combustibles), Class B (flammable liquids), and Class C (electrical fires). Its adaptability makes it a valuable tool in diverse firefighting scenarios.

Types of Fire-Fighting Foam

Types of Fire-Fighting Foam

1. Class A Foam

Class A foam is specifically designed for combating fires involving ordinary combustibles such as wood, paper, cloth, and other common materials. These foams are formulated to enhance water’s effectiveness, making it more adept at penetrating and wetting Class A fuels. 

The primary objective of Class A foam is to reduce the surface tension of water, allowing it to penetrate porous materials more effectively. This improved penetration enhances the water’s ability to cool the fuel source and extinguish the fire.

Key Characteristics and Applications of Class A Foam:

1. Enhanced Penetration:

Class A foam reduces the surface tension of water, enabling it to penetrate and saturate porous materials, which is crucial for extinguishing fires involving ordinary combustibles.

2. Increased Cooling Effect:

By improving water penetration, Class A foam enhances the cooling effect on the fuel source, aiding in the suppression and extinguishment of Class A fires.

3. Versatility:

Class A foam is versatile and can be used with various firefighting equipment, including handlines, nozzles, and compressed air foam systems (CAFS).

2. Class B Foam

Class B foam is specifically formulated for flammable liquid fires, including those involving fuels, oils, and various chemicals. Unlike Class A foam, Class B foam is designed to create a blanket on the surface of flammable liquids, suppressing the release of vapors and preventing reignition. 

These foams are categorized further into subtypes based on their compatibility with different types of fuels and flammable substances.

Key Characteristics and Applications of Class B Foam:

1. Vapor Suppression:

Class B foam forms a cohesive blanket over the liquid surface, suppressing the release of flammable vapors and preventing their ignition. This is crucial in controlling and extinguishing fires involving flammable liquids.

2. Burnback Resistance:

Class B foam provides burn back resistance, reducing the likelihood of reignition by creating a barrier that separates the fuel from potential ignition sources.

3. Subtypes for Specific Fuels:

Class B foams are available in various formulations tailored for specific flammable liquids, ensuring optimal performance in different scenarios. Examples include alcohol-resistant foam (AR-AFFF) for alcohol-based fuels and fluoroprotein foam for certain hydrocarbons.

4. Application Methods:

A Class B foam can be applied using a variety of equipment, including foam nozzles, monitors, and foam proportioning systems. It is commonly used in industries where flammable liquids pose a significant fire risk.

Generally, Class A foam is designed for ordinary combustibles, improving water penetration and cooling, while Class B foam is formulated for flammable liquid fires, creating a vapor-suppressing blanket and providing burn-back resistance. 

Both types of foam play crucial roles in the firefighting arsenal, addressing specific challenges posed by different fire classes.

3. Class AB Foam

Class AB foam, also known as “Aqueous Film-Forming Foam (AFFF),” is a versatile firefighting foam designed to address both Class A (ordinary combustibles) and Class B (flammable liquids) fires. This type of foam is particularly effective in situations where the presence of both solid combustibles and flammable liquids necessitates a dual-purpose solution. 

It combines the features of Class A foam, which enhances water penetration and cooling, with the vapor-suppressing and burnback-resistant properties required for Class B fires.

Key Characteristics and Applications of Class AB Foam:

1. Dual-Class Capabilities:

Class AB foam is formulated to provide effective firefighting capabilities for both Class A and Class B fires. This dual-class versatility makes it a valuable tool in situations where the nature of the fire involves a combination of ordinary combustibles and flammable liquids.

2. Improved Water Penetration:

Similar to Class A foam, Class AB foam reduces the surface tension of water, allowing it to penetrate and saturate porous materials. This is particularly beneficial in situations where the fire involves solid combustibles.

3. Vapor Suppression for Flammable Liquids:

Class AB foam exhibits characteristics similar to Class B foam, creating a protective film on the surface of flammable liquids. This film suppresses the release of vapors, preventing ignition and providing burnback resistance.

4. Compatibility with Various Fuels:

Class AB foam is formulated to be compatible with a wide range of flammable liquids, making it suitable for use in diverse industrial settings where different types of fuels may be present.

5. Application Methods:

Class AB foam can be applied using various firefighting equipment, including handlines, foam nozzles, monitors, and proportioning systems. Its adaptability allows for flexibility in response to different fire scenarios.

6. Common Use in Mixed Fire Incidents:

Class AB foam is commonly used in scenarios where the presence of both solid combustibles and flammable liquids requires a comprehensive firefighting approach. This makes it a go-to solution for incidents in industrial facilities, chemical plants, and similar environments.

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Understanding Fire Types

Understanding Fire Types

1. Class A Fires:

Class A fires involve ordinary combustibles such as wood, paper, cloth, plastic, and other common materials. These fires are characterized by the presence of solid materials that leave ash when burned. Class A fires are typically found in homes, offices, and various everyday environments. 

Effectively combating Class A fires requires the use of water or Class A firefighting foam to cool the fuel source and suppress the flames.

Key Characteristics of Class A Fires:

1. Fuel Type:

Involves ordinary combustibles, including wood, paper, cloth, and plastics.

2. Ash Production:

Leaves ash when burned.

3. Common Locations:

Occurs in residential settings, offices, schools, and places with typical household or office materials.

4. Recommended Extinguishing Agents:

Water is the primary extinguishing agent for Class A fires. Class A firefighting foam can also be effective by enhancing water penetration and cooling.

2. Class B Fires:

Class B fires involve flammable liquids and gases, including gasoline, oil, grease, propane, and other substances that can ignite and burn. These fires are characterized by the presence of liquid or gas fuels, and they can spread rapidly. 

Traditional methods like water may not be effective for Class B fires, as they can cause the spread of flammable liquids. Instead, Class B fires are typically extinguished using specialized firefighting foam designed to suppress vapors and prevent reignition.

Key Characteristics of Class B Fires:

a. Fuel Type:

Involves flammable liquids and gases, such as gasoline, oil, grease, and propane.

b. Liquid or Gas State:

The fuel is typically in a liquid or gas state.

c. Rapid Spread:

Class B fires can spread rapidly due to the volatile nature of flammable liquids.

d. Avoidance of Water:

Water is generally avoided for Class B fires, as it may cause the spread of flammable liquids.

e. Recommended Extinguishing Agents:

Specialized Class B firefighting foam is commonly used to suppress vapors and prevent reignition. Dry chemical extinguishers and carbon dioxide (CO2) are also effective for some Class B fires.

Understanding the distinctions between Class A and Class B fires is crucial for selecting the appropriate firefighting methods and extinguishing agents. Combining the right techniques and materials ensures a more effective response to different fire scenarios, safeguarding lives and property.

Appropriate Foam Types for Each Fire Class

Appropriate Foam Types for Each Fire Class

Selecting the appropriate foam type for each fire class is crucial in firefighting to ensure effective suppression and extinguishment. The two primary classes of foam relevant to fire types are Class A foam and Class B foam.

1. Class A Foam:

Fire Class: Class A fires (involving ordinary combustibles such as wood, paper, cloth, plastics).

Appropriate Use:

  • Class A foam is designed to enhance the effectiveness of water in suppressing and extinguishing Class A fires.
  • It reduces the surface tension of water, allowing it to penetrate porous materials like wood and paper more effectively.

Common Applications:

  • Residential fires, office fires, wildfires, and any incidents involving ordinary combustible materials.

2. Class B Foam

Fire Class: Class B fires (involving flammable liquids and gases such as gasoline, oil, grease, and propane).

Appropriate Use:

Class B foam is formulated to create a cohesive barrier on the surface of flammable liquids, suppressing vapors and preventing reignition.

It provides burnback resistance and is essential for dealing with the volatility of flammable liquids.

Common Applications:

  • Industrial settings, fuel storage facilities, chemical plants, and any incidents involving flammable liquid or gas fires.


  • Different formulations of Class B foam exist, such as Alcohol-Resistant Aqueous Film-Forming Foam (AR-AFFF) for alcohol-based fuels and Fluoroprotein Foam for certain hydrocarbons.

3. Class AB Foam:

Fire Class: Dual-purpose for both Class A and Class B fires.

Appropriate Use:

  • Class AB foam combines the characteristics of Class A and Class B foams, making it versatile for situations involving both solid combustibles and flammable liquids.

Common Applications:

  • Industrial incidents where a combination of ordinary combustibles and flammable liquids is present.
  • Other Specialized Foams:

4. Metal-Affected Foam (MAF):

  • For fires involving alkali metals, which can react violently with water or Class A foam.

5. High-Expansion Foam:

  • For situations where a large volume of foam is needed to fill enclosed spaces, such as basements or tunnels.

Selecting the appropriate foam type depends on a thorough understanding of the specific fire class and the materials involved. Firefighters and emergency responders should be trained to identify the type of fire and use the corresponding foam to achieve the most effective firefighting results

Necessary Equipment and Tools

1. Foam Proportioning Systems:

Foam proportioning systems are devices designed to accurately mix firefighting foam concentrate with water in the correct ratios to produce the desired foam solution. These systems ensure the proper concentration of foam is applied to the fire.

  • Key Components:
    • Proportioner: The core component that controls the ratio of foam concentrate to water.
    • Inline Inductors: Devices that introduce foam concentrate into the water stream.
    • Foam Chambers: Enclosures where the foam solution is generated before being directed to the fire.
  • Types:
    • Fixed Proportioning Systems: Installed in fixed locations, such as industrial facilities or fire suppression systems in buildings.
    • Mobile Proportioning Systems: Portable units mounted on vehicles for rapid deployment in the field.
  • Applications:
    • Large Fires: Used in situations where a significant volume of foam is required, such as industrial fires or incidents involving flammable liquid storage.

2. Foam Generators

Foam generators are devices that produce and deliver firefighting foam to the fire. They play a crucial role in the application of foam on the fire ground.

  • Key Components:
    • Foam Chamber: Where foam concentrate and water are mixed to create the foam solution.
    • Air Aspirating Nozzle: Introduces air into the foam solution, producing foam bubbles.
    • Distribution Device: Directs the foam onto the fire surface.
  • Types:
    • High-Expansion Foam Generators: Produce large volumes of foam for situations where extensive coverage is needed, such as in confined spaces.
    • Low-Expansion Foam Generators: Used for general firefighting applications and providing a stable foam blanket.
  • Applications:
    • Enclosed Spaces: Effective in scenarios where the fire is in a confined area, such as tunnels, basements, or storage tanks.

3. Nozzles and Applicators

Nozzles and applicators are devices used to discharge the foam solution onto the fire. They come in various designs to suit different firefighting applications.

  • Key Components:
    • Control Valve: Regulates the flow of foam solution.
    • Pattern Control: Adjust the spray pattern of the foam.
    • Pickup Tube: Draw the foam concentrate into the water stream.
  • Types:
    • Fixed Nozzles: Mounted in specific locations for permanent fire protection systems.
    • Handheld Nozzles: Portable devices used by firefighters for manual application.
    • Compressed Air Foam Systems (CAFS) Nozzles: Combine foam concentrate, water, and compressed air for enhanced firefighting capabilities.
  • Applications:

              Structural Fires: Used in both indoor and outdoor firefighting scenarios to apply foam directly to the fire or fuel source.

Step-by-Step Guide to Fire-Fighting Foam Application

Step-by-Step Guide to Fire-Fighting Foam Application

A. Assessing the Situation:

  • Size-Up the Fire:
    • Evaluate the size, intensity, and nature of the fire. Consider factors such as the type of fuel involved, the presence of hazardous materials, and potential fire spread.
  • Identify the Fire Class:
    • Determine the fire class (Class A, B, or both) to understand the appropriate firefighting approach and foam type required.
  • Assess Surroundings:
    • Consider the environment, including the presence of confined spaces, potential fire spread, and the safety of personnel.
  • Evaluate Wind Conditions:
    • Determine the direction and speed of the wind to plan the application of firefighting foam effectively and prevent unintended consequences.

B. Selecting the Right Foam Type:

  • Identify Fire Class:
    • Choose the appropriate foam type based on the identified fire class. Use Class A foam for ordinary combustibles and Class B foam for flammable liquids and gases.
  • Consider Fuel Compatibility:
    • If dealing with flammable liquids, select the appropriate Class B foam subtype, such as Alcohol-Resistant Aqueous Film-Forming Foam (AR-AFFF) or Fluoroprotein Foam, based on fuel compatibility.
  • Evaluate Environmental Impact:
    • Consider the potential environmental impact and select foam types that minimize harm to the surroundings, especially in cases of hazardous materials involvement.
  • Assess Equipment Availability:
    • Ensure that the required foam concentrate and equipment are available and compatible with the chosen foam type.

C. Setting Up Equipment:

  • Deploy Foam Proportioning System:
    • Set up and activate the foam proportioning system to ensure the correct mixing of foam concentrate with water. Adjust the proportioning ratio based on the manufacturer’s recommendations.
  • Position Foam Generators:
    • Place foam generators strategically to achieve optimal coverage. Consider the type of generator (high-expansion or low-expansion) based on the fire location and containment requirements.
  • Configure Nozzles and Applicators:
    • Connect and configure nozzles and applicators based on the intended application method. Adjust the foam flow rate and pattern control settings for effective foam deployment.
  • Establish Foam Blanket:
    • Apply the foam to create a protective blanket over the fuel source, ensuring thorough coverage. Start at the base of the fire and work toward the top to smother the flames.
  • Monitor and Adjust:
    • Continuously monitor the foam application and adjust equipment settings as needed. Ensure that the foam blanket is maintained to prevent re-ignition.
  • Reassess and Revise Strategy:
    • Periodically reassess the situation and revise the firefighting strategy as necessary. Consider changing foam types or application methods based on the evolving fire dynamics.

Common Mistakes to Avoid in Firefighting Foam Applications

Common Mistakes to Avoid in Firefighting Foam Applications

A. Overuse of Foam:

  • Failure to Assess Fire Size:
    • Mistake: Applying excessive foam without accurately assessing the size of the fire can lead to unnecessary waste of firefighting foam concentrate.
    • Recommendation: Conduct a thorough size-up of the fire to determine the appropriate amount of foam needed for effective suppression.
  • Lack of Foam Blanket Monitoring:
    • Mistake: Neglecting to monitor the foam blanket and continuing to apply foam after the fire is extinguished can result in overuse and environmental concerns.
    • Recommendation: Regularly assess the effectiveness of the foam blanket and cease application once the fire is under control.
  • Inefficient Application Techniques:
    • Mistake: Improper application techniques, such as using excessive pressure or applying foam too quickly, can lead to wasteful consumption.
    • Recommendation: Train personnel in proper foam application techniques, including nozzle control and pattern adjustment, to optimize foam coverage.

B. Incorrect Foam Concentrations:

  • Proportioning System Errors:
    • Mistake: Improper calibration or setting errors in foam proportioning systems can result in incorrect foam concentrations, reducing firefighting effectiveness.
    • Recommendation: Regularly inspect and calibrate foam proportioning systems to ensure accurate mixing ratios as per the manufacturer’s guidelines.
  • Failure to Adjust for Environmental Factors:
    • Mistake: Neglecting to adjust foam concentrations based on factors like temperature and wind conditions can affect the foam’s performance.
    • Recommendation: Consider environmental factors when determining the appropriate foam concentration, and make necessary adjustments for optimal firefighting results.
  • Inadequate Training:
    • Mistake: Insufficient training on foam concentrate ratios and proper mixing procedures can lead to errors in foam concentration.
    • Recommendation: Provide comprehensive training to firefighting personnel on the correct use of foam proportioning systems and the importance of accurate foam concentrations.

C. Inadequate Equipment Maintenance:

  • Neglecting Regular Inspections:
    • Mistake: Failing to conduct regular inspections of foam equipment, including nozzles, applicators, and proportioning systems, can lead to malfunctions.
    • Recommendation: Establish a routine maintenance schedule and conduct thorough inspections to identify and address any equipment issues promptly.
  • Ignoring Manufacturer Recommendations:
    • Mistake: Disregarding the manufacturer’s maintenance guidelines for foam equipment can result in reduced performance and reliability.
    • Recommendation: Adhere to the manufacturer’s recommended maintenance procedures, including lubrication, cleaning, and replacement of worn parts.
  • Poor Record-Keeping:
    • Mistake: Lack of proper record-keeping for equipment maintenance can lead to oversight and neglect of crucial maintenance tasks.
    • Recommendation: Maintain accurate records of equipment inspections, repairs, and maintenance schedules to ensure timely and thorough upkeep.

By avoiding these common mistakes, firefighting teams can enhance the efficiency and effectiveness of foam application, ensuring a safer and more controlled response to fire incidents.

Frequently Asked Questions

What types of fires can be extinguished with firefighting foam?

What types of fires can be extinguished with firefighting foam

Firefighting foam is versatile and can be used to extinguish various types of fires. It is effective for Class A fires (involving ordinary combustibles like wood and paper) and Class B fires (involving flammable liquids and gases such as gasoline, oil, and propane). 

Foam can also be used in situations where both Class A and Class B fuels are present, making it a dual-purpose solution known as Class AB foam.

How does the foam application process differ for different fire classes?

The foam application process varies based on the fire class. For Class A fires, the foam is applied to enhance the water’s effectiveness in penetrating and cooling ordinary combustibles.

For Class B fires, the foam is designed to form a blanket on the surface of flammable liquids, suppressing vapors and preventing reignition. The application techniques, equipment, and foam types used differ to address the specific characteristics of each fire class.

What safety measures should be taken during foam application?

Safety is paramount during foam application. Key safety measures include:

  • Wear appropriate personal protective equipment (PPE), including protective clothing and respiratory gear.
  • Maintaining a safe distance from the fire to avoid exposure to heat and hazardous conditions.
  • Following established procedures for foam application and firefighting techniques.
  • Communicating effectively with team members and maintaining situational awareness.
  • Adhering to relevant safety regulations and guidelines.

Are there any environmental concerns with using firefighting foam?

Certain firefighting foams, particularly those containing per- and polyfluoroalkyl substances (PFAS), have raised environmental concerns due to their persistence and potential adverse effects. PFAS-containing foams have been associated with groundwater contamination. 

To mitigate environmental impact, many firefighting agencies are transitioning to environmentally friendly foam formulations, and proper containment and cleanup measures are emphasized during foam application.

How often should equipment be inspected and maintained?

Regular equipment inspections and maintenance are crucial for ensuring the reliability and effectiveness of firefighting foam equipment. The frequency of inspections depends on usage, environmental conditions, and manufacturer recommendations. 

Typically, equipment should be inspected at least quarterly, and more frequent checks may be necessary for units used frequently or in demanding environments. Follow the manufacturer’s guidelines for routine maintenance, and conduct thorough inspections to identify and address any issues promptly.


Applying firefighting foam requires careful consideration of several key factors to ensure its effectiveness in suppressing and extinguishing fires.  What is necessary when applying firefighting foam is a proper selection of the appropriate foam type, proportioning equipment, and application technique is crucial. 

Additionally, understanding the specific characteristics of the fire, such as fuel type and environmental conditions, plays a significant role in achieving optimal results.