Chapter Overview With its self-contained features, transportability, ease of use, varied style, and application, the portable fire extinguisher may well be the unsung hero of fire suppression. Despite today s climate of technological advances, and newer, bigger, and more sophisticated apparatus and equipment, this simple yet valuable tool warrants a second look as a first line of defense for fire fighters. After students complete this chapter and the related course work, they will be able to state the primary purpose of portable fire extinguishers. Students will have an understanding of portable fire extinguishers, including the types of agents and operating systems used, the classification and rating system for fire extinguishers, and the basic steps of fire extinguisher operation. Students will also be able to define Class A, B, C, D, and K fires, and identify the safe and effective suppression methods for each. In addition, students will be able to explain the care and maintenance of portable fire extinguishers, including recharging and hydrostatic testing. NFPA Standards NFPA 1001 Standard Fire Fighter I 5.3.16 Extinguish incipient Class A, Class B, and Class C fires, given a selection of portable fire extinguishers, so that the correct extinguisher is chosen, the fire is completely extinguished, and proper extinguisher-handling techniques are followed. 5.3.16 (A) Requisite Knowledge: The classifications of fire; the types of, rating systems for, and risks associated with each class of fire; and the operating methods and limitations of portable fire extinguishers. 5.3.16 (B) Requisite Skills: The ability to operate portable fire extinguishers, approach fire with portable fire extinguishers, select an appropriate extinguisher based on the size and type of fire, and safely carry portable fire extinguishers. Fire Fighter II NFPA 1001 contains no Fire fighter II Job Performance Requirements for this chapter. Additional NFPA Standards NFPA 10, Standard for Portable Fire Extinguishers NFPA 11, Standard for Low-, Medium-, and High-Expansion Foam Objectives and Resources Knowledge Objectives After studying this chapter, you will be able to: State the primary purposes of fire extinguishers. Define Class A fires. Define Class B fires. Define Class C fires. Define Class D fires. Define Class K fires. Explain the classification and rating system for fire extinguishers. Describe the types of agents used in fire extinguishers. Describe the types of operating systems in fire extinguishers. Describe the basic steps of fire extinguisher operation. Explain the basic steps of inspecting, maintaining, recharging, and hydrostatic testing of fire extinguishers. Skills Objectives After completing this chapter, you will be able to perform the following skills: Transport the extinguisher to the location of the fire. Select and operate a portable fire extinguisher safely to effectively extinguish an incipient fire. Attack a Class A fire with a stored-pressure water-type fire extinguisher. Attack a Class A fire with a multipurpose dry chemical fire extinguisher. Attack a Class B flammable liquid fire with a dry chemical fire extinguisher. Attack a Class B flammable liquid fire with a storedpressure foam fire extinguisher.
Use a wet chemical fire extinguisher. Use a halogenated agent-type extinguisher. Use dry powder fire extinguishing agents. Support Materials Dry erase board and markers or chalkboard and chalk LCD projector, slide projector, overhead projector, and projection screen PowerPoint presentation, overhead transparencies, or slides Assortment of portable fire extinguishers to enable each student to discharge Eye protection (instructor and students) for hands-on demonstration and practice Enhancements Direct the students to visit the Internet at www.firefighter.jbpub.com for online activities. Direct the students to relevant sections in the Student Workbook for application of the content introduced in this chapter Direct the students to relevant sections in the Student Review Manual to prepare for examinations. Direct the students to the corresponding online FireLearn module to study the knowledge and critical thinking skills presented online. Teaching Tips Contact a local equipment vendor for samples and literature. Assemble an assortment of portable extinguishers, including several of the obsolete (carbon tetrachloride, sodium bicarbonate) extinguishers to illustrate the evolving technology and safety considerations. Consider a triad teach back to confirm inspection and maintenance skills. Place students in groups of three (multiples of three) and assemble portable extinguishers in sets of three (multiples of three). Label the units 1-2-3 and allow students to select from cards labeled 1-2-3. Each student demonstrates an inspection and states maintenance considerations for the respective unit. Rotate groups as supplies allow. Obtain a copy of NFPA 10, Standard for Portable Fire Extinguishers and the NFPA Fire Protection Handbook for classroom reference. Skill Drill steps are included prior to the section on maintenance. Depending on your audience analysis, you may want to break the class prior to discussing inspection, maintenance, recharging, and hydrostatic testing for hands-on demonstrations and practice, then reconvene to cover care and maintenance issues. This breaks up the amount of information and allows students to apply newly-received information. To aid in recognition of fire classifications, create a mnemonic or memory-jogger such as the following: Class A fires reduce material to ash; Class B materials usually are stored in bottles; Class C materials usually involve current; Class D materials react dramatically to water, and Class K materials usually are involved with kitchens. Reading and Preparation Review all instructional materials, including Fundamentals of Fire Fighter Skills, Chapter 7, and all related presentation support materials. Review local firefighting protocols for Chapter 7. Review Chapter 1, The History and Orientation of the Fire Service, Chapter 5, Fire Behavior, Chapter 16, Fire Hose, Nozzles, Streams, and Foam, Chapter 20, Wildland and Ground Fires, and Chapter 21, Fire Suppression in Fundamentals of Fire Fighter Skills to provide a context for supporting the use of fire extinguishers in today s fire service. Use this as a motivator for anticipating future classes. Familiarize yourself with the content of NFPA 10, Standard for Portable Fire Extinguishers and NFPA 11, Standard for Low-, Medium-, and High- Expansion Foam Systems to be prepared to respond to student questions and/or expand on elements of the text and lesson plan. Prepare a job sheet, series of flash cards, or posters to reinforce identification of extinguisher labels and extinguisher classifications and ratings. Assign as homework or use for an in-class review.
174 Fire Service Instructor: Principles and Practice, Second Edition Presentation Overview Total time: 495 minutes Pre-Lecture I. You Are the Fire Fighter Small Group Activity/Discussion 5 minutes Notes Lecture I. Introduction Lecture/Discussion 5 minutes Notes II. Purposes of Fire Extinguishers Lecture/Discussion 5 minutes Notes III. Classes of Fires Lecture/Discussion 15 minutes Notes IV. Classification of Fire Extinguishers Lecture/Discussion 15 minutes Notes V. Labeling of Fire Extinguishers Lecture/Discussion 15 minutes Notes VI. Fire Extinguisher Placement Lecture/Discussion 20 minutes Notes VII. Types of Extinguishing Agents Lecture/Discussion 65 minutes Notes VIII. Fire Extinguisher Design Lecture/Discussion 15 minutes Notes IX. Fire Extinguisher Characteristics Lecture/Discussion 40 minutes Notes X. Use of Fire Extinguishers Lecture/Discussion 50 minutes Notes XI. The Care of Fire Extinguishers: Inspection, Maintenance, Lecture/Discussion 15 minutes Recharging and Hydrostatic Testing Notes XII. Summary Lecture/Discussion 15 minutes Notes XIII. Skill Drills Demonstration/Group Activity 135 minutes A. Transporting a Fire Extinguisher (Skill Drill 7-1) B. Operating a Carbon Dioxide Extinguisher (Skill Drill 7-2) C. Attacking a Class A Fire with a Stored-Pressure Water-Type Fire Extinguisher (Skill Drill 7-3) D. Attacking a Class A Fire with a Multipurpose Dry Chemical Fire Extinguisher (Skill Drill 7-4) E. Attack a Class B Flammable Liquid Fire with a Dry Chemical Fire Extinguisher (Skill Drill 7-5) F. Attacking a Class B Flammable Liquid Fire with a Stored-Pressure Foam Fire Extinguisher (AFFF or FFFP) (Skill Drill 7-6) G. Use of Wet Chemical Fire Extinguishers (Skill Drill 7-7) H. Use of Halogenated-Agent Type Extinguisher (Skill Drill 7-8) I. Use of Dry Powder Fire Extinguishing Agents (Skill Drill 7-9) Notes
Portable Fire Extinguishers 175 Post-Lecture I. Wrap-Up A. Fire Fighter in Action Small Group Activity/Individual Activity/Discussion 20 minutes B. Technology Resources (www.firefighter.jbpub.com) Small Group Activity/Discussion 20 minutes II. Lesson Review Discussion 15 minutes III. Assignments Lecture 5 minutes IV. Chapter 7 Instructor Keyed Quiz Individual Activity 20 minutes Notes Lesson Plan Pre-Lecture You Are the Fire Fighter Time: 5 minutes Small Group Activity/Discussion Use this activity to motivate students to learn the knowledge and skills needed to safely and effectively use portable fire extinguishers. Purpose To allow students an opportunity to explore the significance and concerns associated with portable fire extinguishers. Instructor Directions 1. Direct students to read the You Are the Fire Fighter scenario found in the beginning of Chapter 7. 2. You may assign students to a partner or a group. Direct them to review the discussion questions at the end of the scenario and prepare a response to each question. Facilitate a class dialogue centered on the discussion questions. 3. You may also assign this as an individual activity and ask students to turn in their comments on a separate piece of paper. Lesson Plan Lecture I. Introduction Time: 5 minutes Slides: 1-5 Lecture/Discussion Slides 1-3 Chapter Objectives Slide 4 Introduction (1 of 2) Extinguishers are used by civilians and fire fighters. Required for commercial vehicles, boats, and aircraft Easy to operate with minimal training A. Portable fire extinguishers are required in a variety of occupancies. B. Both civilians and fire fighters use portable fire extinguishers. C. Most extinguishers are easy to operate with a minimal amount of training.
176 Fire Service Instructor: Principles and Practice, Second Edition Slide 5 Introduction (2 of 2) Extinguishers vary in size and type of extinguishing agent used. Selection of appropriate extinguisher is critical. Proper use reduces injury and property damage. D. Extinguishers vary in size and type of extinguishing agent used. 1. Agents include water, water with additives, dry chemicals, dry powders, and gaseous agents. E. Extinguishers are designed for different purposes; selecting the appropriate extinguisher and knowing how to safely operate it is critical. F. Proper use of extinguishers reduces the risk of personal injury and property damage. II. Purposes of Fire Extinguishers Time: 5 minutes Slide: 6 Lecture/Discussion Slide 6 Purposes of Fire Extinguishers Used to extinguish incipient fires Used to extinguish fires where traditional suppression methods not recommended Most departments carry at least one. Often used by fire fighters for incipient fires Must know Which fires require special extinguishing agents What type of extinguisher to use How to operate each type of extinguisher A. Portable fire extinguishers have two primary uses: to extinguish incipient fires (those that have not spread beyond the area of origin) and to control fires where traditional methods of fire suppression are not recommended. B. Fire extinguishers are placed in many locations so that they will be available for immediate use on small, incipient-stage fires. 1. A trained individual with a suitable fire extinguisher could easily control this type of fire. 2. As the flames spread beyond the area of origin, the fire becomes increasingly difficult to control with only a portable fire extinguisher. C. Fire extinguishers are also used to control fires where traditional extinguishing methods are not recommended. 1. For example, using water on fires that involve energized electrical equipment increases the risk of electrocution to fire fighters. 2. Special extinguishing agents are also required for fires that involve flammable liquids, cooking oils, and combustible metals. D. Most fire department vehicles carry at least one fire extinguisher; many vehicles carry two or more extinguishers of different types. E. Fire fighters often use these portable extinguishers to control incipient-stage fires quickly. 1. One advantage of fire extinguishers is their portability. 2. The primary disadvantage of fire extinguishers is that they are one-shot devices.
Portable Fire Extinguishers 177 F. As a fire fighter, you must know which fires require special extinguishing agents, what type of extinguisher should be used, and how to operate the different types of specialpurpose extinguishers. 1. Portable extinguishers are sometimes used in combination with other techniques. 2. Certain types of portable extinguishers can be helpful in overhauling a fire. III. Classes of Fires Time: 15 minutes Slides: 7-12 Lecture/Discussion Slide 7 Classes of Fires Essential to match extinguisher and fire Both grouped by their characteristics Some agents more efficient on certain fires. Some agents will not control certain fires Some agents are dangerous when applied to certain fires. Slide 8 Class A Fires Class A fires involve items such as: Ordinary wood Rubber Household rubbish Natural vegetation Water is most common extinguishing agent. Slide 9 Class B Fires Class B fires involve items such as: Flammable liquids and gases Oil Grease Tar Some plastics Several agents can be used. A. It is essential to match the appropriate type of extinguisher to the type of fire. B. Fires and fire extinguishers are grouped into classes according to their characteristics. 1. Some extinguishing agents work more efficiently than others on certain types of fires. 2. In some cases, selecting the proper extinguishing agent will mean the difference between extinguishing a fire and being unable to control it. 3. More importantly, in some cases it is dangerous to apply the wrong extinguishing agent to a fire. 4. Using a water extinguisher on an electrical fire can cause an electrical shock as well as a short circuit in the equipment. 5. A water extinguisher should never be used to fight a grease fire. 6. Before selecting a fire extinguisher, ask yourself, What class of fire am I fighting? C. Class A fires involve ordinary combustibles such as wood, paper, cloth, rubber, household rubbish, and some plastics. 1. Natural vegetation, such as grass and trees, is also Class A material. 2. Water is the most commonly used extinguishing agent for Class A fires, although several other agents can be used effectively. D. Class B fires involve flammable or combustible liquids, such as gasoline, oil, grease, tar, lacquer, oil-based paints, and some plastics. 1. Fires involving flammable gases, such as propane or natural gas, are also categorized as Class B fires. 2. Several different types of extinguishing agents are approved for Class B fires.
178 Fire Service Instructor: Principles and Practice, Second Edition Slide 10 Class C Fires Class C fires involve energized electrical equipment such as: Building wiring Circuit breakers Transformers Power tools Require agents that will not conduct electricity Slide 11 Class D Fires Class D fires involve combustible metals such as: Magnesium Sodium Lithium Potassium Violent reactions to water and other agents can occur. Slide 12 Class K Fires New classification due to cooking trends Involve combustible cooking oils and fats Some restaurants still use Class B extinguishers. E. Class C fires involve energized electrical equipment, which includes any device that uses, produces, or delivers electrical energy. 1. A Class C fire could involve building wiring and outlets, fuse boxes, circuit breakers, transformers, generators, or electric motors. 2. Power tools, lighting fixtures, household appliances, and electronic devices such as televisions, radios, and computers could be involved in Class C fires. 3. The equipment must be plugged in or connected to an electrical source, but not necessarily operating. 4. Electricity does not burn, but electrical energy can generate tremendous heat that could ignite nearby Class A or B materials. 5. As long as the equipment is energized, it must be treated as a Class C fire. 6. Agents that will not conduct electricity, such as dry chemicals or carbon dioxide, must be used on Class C fires. F. Class D fires involve combustible metals such as magnesium, titanium, zirconium, sodium, lithium, and potassium. 1. Special techniques and extinguishing agents are required to fight combustible metals fires. 2. Normal extinguishing agents can react violently, even explosively, if they come in contact with burning metals. 3. Violent reactions also can occur when water strikes burning combustible metals. 4. Class D fires are most often encountered in industrial occupancies, such as machine shops and repair shops, as well as in fires involving aircraft and automobiles. 5. Because of the chemical reactions that could occur during a Class D fire, it is important to select the proper extinguishing agent and application technique. 6. Choosing the correct fire extinguisher for a Class D fire requires expert knowledge and experience. G. Class K fires involve combustible cooking oils and fats. 1. The use of high-efficiency modern cooking equipment and the trend toward using vegetable oils instead of animal fats to fry foods required the development of a new class of extinguishing agents. 2. Many restaurants are still using extinguishing agents that were approved for Class B fires.
Portable Fire Extinguishers 179 IV. Classification of Fire Extinguishers Time: 15 minutes Slides: 13-17 Lecture/Discussion Slide 13 Classification of Fire Extinguishers (1 of 5) Classification and rating based on characteristics and capabilities. Underwriters Laboratories, Inc. (UL) develops standards for ratings and classification. Extinguishers are rated for safety and effectiveness. May have multiple letters if effective on more than one class of fire Slide 14 Classification of Fire Extinguishers (2 of 5) Letters indicate class of fire for which extinguisher can be used. Numbers indicate effectiveness for Class A and B extinguishers by a nonexpert user. Slide 15 Classification of Fire Extinguishers (3 of 5) Class A Fire extinguishers Number is related to amount of water. 1-A rated contains equivalent of 1.25 gallons of water. 2-A rated contains equivalent of 2.5 gallons of water. 4-A rated should extinguish approximately twice as much fire as a rated 2-A. Slide 16 Classification of Fire Extinguishers (4 of 5) Class B Fire Extinguishers Number is based on approximate square feet of burning fuel that can be extinguished. 10-B rated will extinguish 10 square feet of fire. 40-B rated will extinguish 40 square feet of fire. A. Portable fire extinguishers are classified and rated based on their characteristics and capabilities. 1. This information is important for selecting the proper extinguisher to fight a particular fire. 2. It is also used to determine what type or types of fire extinguishers should be placed in a given location so that incipient fires can be quickly controlled. B. In the United States, Underwriters Laboratories, Inc. (UL) is the organization that developed the standards, classification, and rating system for portable fire extinguishers. 1. Each fire extinguisher has a specific rating that identifies the class or classes of fires for which it is both safe and effective. C. The classification system for fire extinguishers uses letters and numbers. 1. The letters indicate the class or classes of fire for which the extinguisher can be used. 2. The numbers indicate its effectiveness. 3. Fire extinguishers that are safe and effective for more than one class will be rated with multiple letters. 4. Class A and Class B fire extinguishers also include a number, indicating the relative effectiveness of the fire extinguisher in the hands of a non-expert user. 5. On Class A extinguishers, the number is related to an amount of water. a. An extinguisher that is rated 1-A contains the equivalent of 1.25 gallons of water. b. A typical Class A extinguisher contains 2.5 gallons of water and has a 2-A rating. c. The higher the number, the greater the extinguishing capability of the extinguisher. d. An extinguisher that is rated 4-A should be able to extinguish approximately twice as much fire as one that is rated 2-A. 6. The effectiveness of Class B extinguishers is based on the approximate area (measured in square feet) of burning fuel they are capable of extinguishing. a. A 10-B rating indicates that a non-expert user should be able to extinguish a fire in a pan of flammable liquid that is 10 square feet in surface area. b. An extinguisher rated 40-B should be able to control a flammable liquid pan fire with a surface area of 40 square feet.
180 Fire Service Instructor: Principles and Practice, Second Edition Slide 17 Classification of Fire Extinguishers (5 of 5) Class C extinguishers use agents that do not conduct electricity. 7. Numbers are used to rate an extinguisher s effectiveness only for Class A and Class B fires. 8. If the fire extinguisher can also be used for Class C fires, it contains an agent proven to be nonconductive to electricity and safe for use on energized electrical equipment. a. For instance, a fire extinguisher that carries a 2-A:10-B:C rating can be used on Class A, Class B, and Class C fires. b. It has the extinguishing capabilities of a 2-A extinguisher when applied to Class A fires, the capabilities of a 10-B extinguisher for Class B fires, and can be used safely on energized electrical equipment. D. Standard test fires are used to rate the effectiveness of fire extinguishers. 1. The testing may involve different agents, amounts, application rates, and application methods. 2. Fire extinguishers are rated for their ability to control a specific type of fire as well as for the extinguishing agent s ability to prevent rekindling. 3. Some agents can successfully suppress a fire, but are unable to prevent the material from re-igniting. 4. A rating is only given if the extinguisher completely extinguishes the standard test fire and prevents rekindling. V. Labeling of Fire Extinguishers Time: 15 minutes Slides: 18-20 Lecture/Discussion Slide 18 Labeling of Fire Extinguishers (1 of 3) Traditional lettering system: Class A green triangle Class B red square Class C blue circle Class D yellow star No traditional-system alphabet graphic for Class K A. Fire extinguishers that have been tested and approved by an independent laboratory are labeled to clearly designate the class or classes of fire the unit is capable of extinguishing safely. B. The traditional lettering system has been used for many years and is still found on many fire extinguishers. C. Recently, however, a universal pictograph system, which does not require the user to be familiar with the alphabetic codes for the different classes of fires, has been developed. D. The traditional lettering system uses the following labels: 1. Extinguishers suitable for use on Class A fires are identified by the letter A on a solid green triangle. a. The triangle has a graphic relationship to the letter A. 2. Extinguishers suitable for use on Class B fires are identified by the letter B on a solid red square. a. Again, the shape of the letter mirrors the graphic shape of the box. 3. Extinguishers suitable for use on Class C fires are identified by the letter C on a solid blue circle, which also incorporates a graphic relationship between the letter C and the circle.
Portable Fire Extinguishers 181 Slide 19 Labeling of Fire Extinguishers (2 of 3) Pictograph system: Square icons representing each class of fire Class A, Class B, Class C, and Class K have pictographs. Slide 20 Labeling of Fire Extinguishers (3 of 3) Icon represents the rating for the class of fire. No icon no rating Red slash indicates that the extinguisher must not be used on that type of fire. Some Class B and C extinguishers exclude Class A fires based on effectiveness. 4. Extinguishers suitable for use on Class D fires are identified by the letter D on a solid yellow five-pointed star. 5. Extinguishers suitable for use on Class K (combustible cooking oil) fires are identified by a pictograph showing a fire in a frying pan. Because the Class K designation is new, there is no traditional system alphabet graphic for it. E. The pictograph system, such as described for Class K fire extinguishers, uses symbols rather than letters on the labels. 1. This system also clearly indicates if an extinguisher is inappropriate for use on a particular class of fire. 2. The pictographs are all square icons that are designed to represent each class of fire. a. The icon for Class A fires is a burning trash can beside a wood fire. b. The Class B fire extinguisher icon is a flame and a gasoline can. c. The Class C icon is a flame and an electrical plug and socket. d. There is no pictograph for Class D extinguishers. e. Extinguishers rated for fighting Class K fires are labeled with an icon showing a fire in the frying pan. 3. Under this pictograph labeling system, the presence of an icon indicates that the extinguisher has been rated for that class of fire. 4. A missing icon indicates that the extinguisher has not been rated for that class of fire. 5. A red slash across an icon indicates that the extinguisher must not be used on that type of fire, because doing so would create additional risk. 6. An extinguisher rated for Class A fires only would show all three icons, but the icons for Class B and Class C would have a red diagonal line through them. 7. Certain extinguishers labeled for Class B and Class C fires do not include the Class A icon, but may be used to put out small Class A fires. VI. Fire Extinguisher Placement Time: 20 minutes Slides: 21-31 Lecture/Discussion Slide 21 Fire Extinguisher Placement (1 of 2) NFPA 10 list recommendations for placing and mounting portable fire extinguishers. Occupancy regulations specify area protected, travel distance from extinguisher to fire, and types of extinguishers provided. Two factors to consider to determine the type of extinguisher: Class of fire likely to occur Potential magnitude of an incipient fire A. Fire codes and regulations require the installation of fire extinguishers in many areas so that they will be available to fight incipient fires. B. NFPA 10 lists the recommendations for placing and mounting portable fire extinguishers as well as the recommended mounting heights. C. The regulations for each type of occupancy specify the maximum floor area that can be protected by each extinguisher, the maximum travel distance from the closest extinguisher to a potential fire, and the types of fire extinguishers that should be provided. D. Two key factors must be considered when determining which type of extinguisher should be placed in each area: the class of fire that is likely to occur and the potential magnitude of an incipient fire.
182 Fire Service Instructor: Principles and Practice, Second Edition Slide 22 Fire Extinguisher Placement (2 of 2) Extinguishers should be readily visible and easily accessed. Do not mount heavy extinguishers high on a wall. NFPA 10 recommends mounting heights. Slide 23 Classifying Area Hazards Risk classification based on amount and type of combustibles and typical situations for occupancy. Fire load Quantity of combustible materials present Includes building materials, contents, and furnishings Measured as the average weight of combustibles per square foot The larger the load, the larger the potential fire Slide 24 Light or Low Hazard (1 of 2) Areas where the majority of materials are noncombustible Arranged so that a fire is not likely to spread Contain limited amounts of Class A and Class B combustibles Slide 25 Light or Low Hazard (2 of 2) Common light hazard environments include: Offices Classrooms Churches Hotel guest rooms E. Extinguishers should be mounted so they are readily visible and easily accessed. F. According to NFPA 10, the recommended mounting heights for the placement of fire extinguishers are: 1. Fire extinguishers weighing up to 40 lb (18.14 kg) should be mounted so that the top of the extinguisher is not more than 5 (1.53 m) above the floor. 2. Fire extinguishers weighing more than 40 lb (18.14 kg) should be mounted so that the top of the extinguisher is not more than 31/2 (1.07 m) above the floor. 3. The bottom of an extinguisher should be at least 4 (10.2 cm) above the floor. G. Areas are divided into three risk classifications light, ordinary, and extra hazard according to the amount and type of combustibles that are present, including building materials, contents, decorations, and furniture. 1. Occupancy use category does not necessarily determine the appropriate hazard classification. 2. The recommended hazard classifications for different types of occupancies are guidelines, based on typical situations. 3. The hazard classification for each area should be based on the actual amount and type of combustibles that are present. 4. Light (or low) hazard areas are locations where the majority of materials are noncombustible or arranged so that a fire is not likely to spread. a. Light hazard environments usually contain limited amounts of Class A combustibles, such as wood, paper products, cloth, and similar materials. b. A light hazard environment might also contain some Class B combustibles (flammable liquids and gases), such as copy machine chemicals or modest quantities of paints and solvents, but all Class B materials must be kept in closed containers and stored safely. c. Examples of common light hazard environments are most offices, classrooms, churches, assembly halls, and hotel guest rooms.
Portable Fire Extinguishers 183 Slide 26 Ordinary or Moderate Hazard Contain more Class A and Class B materials than light hazard locations Examples include: Auto showrooms Research facilities Parking garages Slide 27 Extra or High Hazard (1 of 2) Contain more Class A and Class B materials than ordinary hazard locations Slide 28 Extra or High Hazard (2 of 2) Examples include: Woodworking shops Kitchens that have deep fryers, flammable liquids, or gases under pressure Facilities used for storing flammable liquids Slide 29 Determining the Appropriate Class of Fire Extinguisher Consider the types and quantities of fuels found in the area. Multipurpose dry chemical extinguishers often used in areas containing low to moderate hazards. Facilities present a variety of conditions. Evaluate each area and tailor the installation. 5. The ordinary (or moderate) hazard category describes locations that contain more Class A and Class B materials than are found in light hazard locations. a. Typical examples of ordinary hazard locations include retail stores with onsite storage areas, light manufacturing facilities, auto showrooms, parking garages, research facilities, and workshops or service areas that support light hazard locations, such as hotel laundry rooms or restaurant kitchens. b. Ordinary hazard areas also include warehouses that contain Class I and Class II commodities. i. Class I commodities include noncombustible products stored on wooden pallets or in corrugated cartons that are shrink-wrapped or wrapped in paper. ii. Class II commodities include noncombustible products stored in wooden crates or multilayered corrugated cartons. 6. The extra (or high) hazard category describes locations that contain more Class A combustibles and/or Class B flammables than are found in ordinary hazard environments. a. Typical examples of extra hazard areas include woodworking shops; service or repair facilities for cars, aircraft, or boats; and many kitchens and other cooking areas that have deep fryers, flammable liquids, or gases under pressure. b. In addition, areas used for manufacturing processes such as painting, dipping, or coating, and facilities used for storing or handling flammable liquids are classified as extra hazard environments. c. Warehouses containing products that do not meet the definitions of Class I and Class II commodities are also considered extra hazard locations. H. Several factors must be considered when determining the number and types of fire extinguishers that should be placed in each area of an occupancy. 1. Among these factors are the types of fuels found in the area and the quantities of those materials. 2. Some areas may need extinguishers with more than one rating or more than one type of fire extinguisher. 3. Most buildings require extinguishers that are suitable for fighting Class A fires because ordinary combustible materials, such as furniture, partitions, interior finish materials, paper and packaging products, are so common. 4. Multipurpose dry chemical extinguishers (rated to fight Class A, B, and C fires) are often used in areas containing a combination of low to moderate hazards. 5. A single multipurpose extinguisher is generally less expensive than two individual fire extinguishers and eliminates the problem of selecting the proper extinguisher for a particular fire. 6. However, it is sometimes more appropriate to install Class A extinguishers in general use areas and to place extinguishers that are especially effective in fighting Class B or Class C fires near those hazards.
184 Fire Service Instructor: Principles and Practice, Second Edition Slide 30 Methods of Fire Extinguishment (1 of 2) Understanding the nature of fire helps to understand how extinguishing agents work. Fires require fuel, heat, and oxygen. Rapid oxidation Occurs when a fuel is combined with oxygen Combustion Occurs when fuel is heated to its kindling temperature Slide 31 Methods of Fire Extinguishment (2 of 2) Extinguishers stop burning by: Cooling the fuel Cutting off the supply of oxygen Interrupting the chain of reactions 7. Some facilities present a variety of conditions. In these occupancies, each area must be individually evaluated so that extinguisher installation is tailored to the particular circumstances. a. A restaurant is a good example of this situation. i. The dining areas contain common combustibles, such as furniture, tablecloths, and paper products, that would require an extinguisher rated for Class A fires. ii. In the restaurant s kitchen, where the risk of fire involves cooking oils, a Class K extinguisher would provide the best defense. b. Similarly, within a hospital, extinguishers for Class A fires would be appropriate in the hallways, offices, lobbies, and patient rooms. i. Class B extinguishers should be mounted in laboratories and areas where flammable anesthetics are stored or handled. ii. Electrical rooms should have extinguishers that are approved for use on Class C fires. iii. Hospital kitchens would need Class K extinguishers. I. Methods of Extinguishment 1. Understanding the nature of fire is key to understanding how extinguishing agents work and how they differ from each other. 2. All fires require three basic ingredients: fuel, heat, and oxygen. 3. Scientifically, burning is called rapid oxidation. a. It is a chemical process that occurs when a fuel is combined with oxygen, resulting in the formation of ash or other waste products and the release of energy as heat and light. 4. The combustion process begins when the fuel is heated to its kindling temperature (also known as the kindling point or ignition point) the temperature at which it begins to burn. 5. The energy that initiates the process can come from many different sources, including a spark or flame, friction, electrical energy, or a chemical reaction. 6. Once a substance begins to burn, it will generally continue burning as long as there are adequate supplies of oxygen and fuel to sustain the chemical reaction, unless something interrupts the process. 7. Most extinguishers stop the burning by cooling the fuel below its kindling temperature, by cutting off the supply of oxygen, or by combining these two techniques. 8. Some extinguishing agents interrupt the complex system of molecular chain reactions that occur between the heated fuel and the oxygen. 9. If the temperature of the fuel falls below its ignition point or kindling temperature, the combustion process will stop. a. Water extinguishes a fire using this method. 10. Creating a barrier that interrupts the flow of oxygen to the flames will also extinguish a fire. a. Putting a lid on a pan of burning food is an example of this technique. b. Applying a blanket of foam to the surface of a burning liquid is another example. c. Surrounding the fuel with a layer of carbon dioxide can also cut off the supply of oxygen necessary to sustain the burning process. d. Some extinguishing agents work by interrupting the molecular chain reactions required to sustain combustion.
Portable Fire Extinguishers 185 VII. Types of Extinguishing Agents Time: 65 minutes Slides: 32-45 Lecture/Discussion Slide 32 Extinguishing Agents Substance contained in portable fire extinguisher that puts out a fire Various chemicals are used (including water). Best agent for a particular hazard depends on several factors. Types of materials involved Anticipated size of the fire Slide 33 Types of Extinguishing Agents Water Dry chemicals Carbon dioxide Foam Wet chemicals Halogenated agents Dry powder Slide 34 Water Efficient, plentiful, and inexpensive Converts from liquid to steam, absorbing heat in the process Effective on Class A fires Less effective or dangerous on other classes Loaded-stream extinguishers used in areas subject to freezing Wetting agents can be added for penetration. A. An extinguishing agent is the substance contained in a portable fire extinguisher that puts out a fire. B. Various different chemicals, including water, are used in portable fire extinguishers. C. The best extinguishing agent for a particular hazard depends on several factors, including the types of materials involved and the anticipated size of the fire. D. Portable fire extinguishers use seven basic types of extinguishing agents: 1. Water 2. Dry chemicals 3. Carbon dioxide 4. Foam 5. Wet chemicals 6. Halogenated agents 7. Dry powder E. Water 1. Water is an efficient, plentiful, and inexpensive extinguishing agent. 2. When applied to fire, water converts from liquid into steam, absorbing heat in the process. 3. Water is very effective for extinguishing Class A fires. 4. Many Class A fuels absorb water, which lowers the temperature of the fuel and prevents rekindling. 5. Water is a much less effective extinguishing agent for other fire classes. a. Applying water to hot cooking oil can cause splattering, which can spread the fire and possibly endanger the extinguisher operator. b. Burning flammable liquids will float on top of water. c. Because water conducts electricity, it is dangerous to apply a stream of water to any fire that involves energized electrical equipment. d. If water is applied to a burning combustible metal, a violent reaction can occur. e. Because of these limitations, plain water is only used in Class A fire extinguishers. 6. One disadvantage of water is that it freezes at 32º F (0º C). a. In areas that are subject to freezing, loaded-stream extinguishers can be used. i. These extinguishers combine an alkali metal salt and water. ii. The salt lowers the freezing point of water, so the extinguisher can be used in much colder areas. b. Wetting agents can also be added to the water in a fire extinguisher. i. These agents reduce the surface tension of the water, allowing it to penetrate more effectively into many fuels, such as baled cotton or fibrous materials.
186 Fire Service Instructor: Principles and Practice, Second Edition Slide 35 Dry Chemical (1 of 3) Stream of finely ground particles Different types of compounds are used. Extinguish in two ways: Interrupts chemical chain reaction Absorbs large quantities of heat Slide 36 Dry Chemical (2 of 3) Several advantages over water extinguishers Ordinary: suitable for Class B and C fires Multipurpose: rated for Class A, B, and C fires Slide 37 Dry Chemical (3 of 3) Additives prevent packing and caking. Disadvantage: chemicals are corrosive. Primary compounds used in dry chemical extinguishers: Sodium bicarbonate Potassium bicarbonate Urea-based potassium carbonate Potassium chloride Ammonium phosphate F. Dry Chemical 1. Dry chemical fire extinguishers deliver a stream of very finely ground particles onto a fire. 2. Different chemical compounds are used to produce extinguishers of varying capabilities and characteristics. 3. The dry chemical extinguishing agents work in two ways. a. First, the dry chemicals interrupt the chemical chain reactions that occur within the combustion process. b. In addition, the tremendous surface area of the finely ground particles allows them to absorb large quantities of heat. 4. Dry chemical extinguishing agents offer several advantages over water extinguishers: a. They are effective on Class B (flammable liquids and gases) fires. b. They can be used on Class C (energized electrical equipment) fires, because the chemicals are nonconductive. c. They are not subject to freezing. 5. The first dry chemical extinguishers were introduced during the 1950s and were rated only for Class B and C fires. a. The industry term for these B:C-rated units is ordinary dry chemical extinguishers. 6. During the 1960s multipurpose dry chemical extinguishers were introduced. a. These extinguishers are rated for Class A, B, and C fires. b. The chemicals in these extinguishers form a crust over Class A combustible fuels to prevent rekindling. 7. Multipurpose dry chemical extinguishing agents are in the form of fine particles and are treated with other chemicals to help maintain an even flow when the extinguisher is being used. 8. Additional additives prevent them from absorbing moisture, which could cause packing or caking and interfere with the discharge. 9. One disadvantage of dry chemical extinguishers is that the chemicals, particularly the multipurpose dry chemicals, are corrosive and can damage electronic equipment, such as computers, telephones, and copy machines. a. The fine particles are carried by the air and settle like a fine dust inside the equipment. b. Over a period of months, the residue can corrode metal parts, causing considerable damage. 10. If electronic equipment is exposed to multipurpose dry chemical extinguishing agents, it should be cleaned professionally within 48 hours after exposure. 11. The five primary compounds used as dry chemicals extinguishing agents are: a. Sodium bicarbonate (rated for Class B and C fires only) i. Sodium bicarbonate is often used in small household extinguishers. b. Potassium bicarbonate (rated for Class B and C fires only) i. Potassium bicarbonate has greater fire-extinguishing capabilities (per unit volume) for Class B fires than sodium bicarbonate. c. Urea-based potassium bicarbonate (rated for Class B and C fires only) i. Urea-based potassium bicarbonate has greater fire-extinguishing capabilities (per unit volume) for Class B fires than sodium bicarbonate.
Portable Fire Extinguishers 187 Slide 38 Carbon Dioxide (1 of 3) 1.5 times heavier than air Forms a dense cloud displacing air surrounding the fuel Interrupts combustion by Reducing the oxygen Disrupts liquid fuel s ability to vaporize Slide 39 Carbon Dioxide (2 of 3) Stored under pressure as a liquid Rated for Class B and C fires only Slide 40 Carbon Dioxide (3 of 3) Limitations include: Heavier than similarly rated extinguishers Short discharge range Does not perform well below 0º F or in wind Suffocation hazard in confined spaces Not suitable for pressurized fuel or cooking grease fires d. Potassium chloride (rated for Class B and C fires only) i. Potassium chloride has greater fire-extinguishing capabilities (per unit volume) for Class B fires than sodium bicarbonate. ii. Potassium chloride is more corrosive than the other dry chemical extinguishing agents. e. Ammonium phosphate (rated for Class A, B, and C fires) i. Ammonium phosphate is the only dry chemical extinguishing agent rated as suitable for use on Class A fires. 12. Although ordinary dry chemical extinguishers can also be used against Class A (common combustibles) fires, a water dousing is also needed to extinguish any smoldering embers and prevent rekindling. 13. Which dry chemical extinguisher to use depends on the compatibility of different agents with each other and with products they might contact. 14. Some dry chemical extinguishing agents cannot be used in combination with particular types of foam. G. Carbon Dioxide 1. Carbon dioxide (CO 2 ) is a gas that is 1.5 times heavier than air. 2. When carbon dioxide is discharged on a fire, it forms a dense cloud that displaces the air surrounding the fuel. 3. This interrupts the combustion process by reducing the amount of oxygen that can reach the fuel. 4. A blanket of carbon dioxide over the surface of a liquid fuel can also disrupt the fuel s ability to vaporize. 5. In portable fire extinguishers, carbon dioxide is stored under pressure as a liquid. a. It is colorless and odorless. It is discharged through a hose and expelled on the fire through a horn. b. When it is released, the carbon dioxide is very cold and forms a visible cloud of dry ice because moisture in the air will freeze when it comes into contact with the carbon dioxide. 6. Carbon dioxide is rated for Class B and C fires only. 7. It does not conduct electricity and has two significant advantages over dry chemical agents: it is not corrosive and it does not leave any residue. 8. Carbon dioxide also has several limitations and disadvantages. These include: a. Weight: Carbon dioxide extinguishers are heavier than similarly rated extinguishers that use other extinguishing agents. b. Range: Carbon dioxide extinguishers have a short discharge range, which requires the operator to be close to the fire, increasing the risk of personal injury. c. Weather: Carbon dioxide does not perform well at temperatures below 0º F ( 18º C) or in windy or drafty conditions because it dissipates before it reaches the fire. d. Confined spaces: When used in confined areas, carbon dioxide dilutes the oxygen in the air. e. Suitability: Carbon dioxide extinguishers are not suitable for use on fires involving pressurized fuel or on cooking grease fires.
188 Fire Service Instructor: Principles and Practice, Second Edition Slide 41 Foam Water-based foam concentrate solution Nozzles introduce air to form foam blanket. Use on Class A or B fires Additives depend on compatibility with fuels. Some foams approved for polar solvents Not suitable for Class C fires Cannot be stored or used at freezing temperatures Slide 42 Wet Chemical Only agent to meet Class K fire rating Chemicals applied as water solutions Formulated for use in commercial kitchens Saponification turns oils and fats to soap or foam. Creates thick blanket to smother the fire and prevent re-ignition Discharged as a fine spray Very effective and easier clean up H. Foam 1. Foam fire extinguishers discharge a water-based solution with a measured amount of foam concentrate added. 2. The nozzles on foam extinguishers are designed to introduce air into the discharge stream, thus producing a foam blanket. 3. Foam extinguishing agents are formulated for use on either Class A or Class B fires. 4. Class A foam extinguishers for ordinary combustible fires extinguish fires in the same way that water extinguishes fires. a. This type of extinguisher can be produced by adding Class A foam concentrate to the water in a standard, 2.5 gallons, stored-pressure extinguisher. b. The foam concentrate reduces the surface tension of the water, allowing for better penetration into the burning materials. 5. Class B foam extinguishers discharge a foam solution that floats across the surface of a burning liquid and prevents the fuel from vaporizing. a. The foam blanket forms a barrier between the fuel and the oxygen, extinguishing the flames and preventing re-ignition. b. These agents are not suitable for Class B fires that involve pressurized fuels or cooking oils. c. The most common Class B additives are aqueous film-forming foam (AFFF) and film-forming fluoroprotein (FFFP) foam. i. Both concentrates produce very effective foams. ii. Which one should be used depends on the product s compatibility with a particular flammable liquid and other extinguishing agents that could be used on the same fire. d. Some Class B foam extinguishing agents are approved for use on polar solvents, which are water-soluble flammable liquids such as alcohols, acetone, esters, and ketones. i. Only extinguishers that are specifically labeled for use with polar solvents should be used if these products are present. e. Although they are not specifically intended for Class A fires, most Class B foams can also be used on ordinary combustibles. i. The reverse is not true, however; Class A foams are not effective on Class B fires. 6. Foam extinguishers are not suitable for use on Class C fires and cannot be stored or used at freezing temperatures. I. Wet Chemical 1. Wet chemical extinguishers are the only type of extinguisher to qualify under the new Class K rating requirements. 2. They use wet chemical extinguishing agents, which are chemicals applied as water solutions. 3. Before Class K extinguishing agents were developed, most fire extinguishing systems for kitchens used dry chemicals. a. The minimum requirement for a commercial kitchen was a 40-B-rated sodium bicarbonate or potassium bicarbonate extinguisher. b. These systems required extensive clean-up after their use, which often resulted in serious business interruptions. 4. All new fixed extinguishing systems in restaurants and commercial kitchens now use wet chemical extinguishing agents. a. These agents are specifically formulated for use in commercial kitchens and foodproduct manufacturing facilities, especially where food is cooked in a deep fryer. b. The fixed systems discharge the agent directly over the cooking surfaces. c. There is no numeric rating of their efficiency in portable fire extinguishers.