The Portable Fire Extinguisher
When used properly, portable fire extinguishers can save lives and limit property damage by putting out a small fire, or containing it until the fire department arrives.
The majority of extinguishers put out a fire by reducing the heat or smothering the fire and thereby depriving it of oxygen.
The Portable Fire Extinguisher (cont.)
A "portable fire extinguisher" is defined as an appliance, apparatus, container or device that is designed to be, or is capable of being, readily moved and that contains or produces any liquid, powder or gas usable for the purpose of extinguishing fire. This definition includes items for recharge or refill.
While proper procedure and training can minimize the chances of an accidental fire, you must still be prepared to deal with a fire emergency should one occur. This section of the program will teach you the basics about fire extinguishers - types, how to use them, when and when not to use them as well as the proper procedures to follow should a fire occur.
Fire Extinguisher Use – The Basics
• Any operator of an extinguisher must be knowledgeable in how to use the extinguisher. The directions on use for each type of extinguisher found in the workplace need to be read and understood before an emergency occurs
• All extinguishers must be inspected and properly serviced on a regular basis. Extinguishers should be inspected on a monthly basis and this inspection should be a part of your overall inspection and maintenance plan to ensure that all extinguishers are in working order and fully charged
• Extinguishers should be easily accessible and the appropriate number available
• The operator must have and maintain a clear escape route that will not be blocked by fire
• The extinguisher must match the type of fire. For example, extinguishers that contain water are unsuitable for use for grease or electrical fires
• The extinguisher must be large enough to put out the fire. Many portable extinguishers may discharge completely in as few as 10 seconds.
Combating the Fire
As we will learn, there are different types of fire and different types of extinguishers to deal with them. We will now take a look at the basic materials used to extinguish fires – as we will see they all have their advantages and disadvantages depending on the type of fire. In this section of the course reference is made to the types of fire – Class A, B, C, and D. These “Classes” will be examined in detail later in the course.
Remember - portable fire extinguishers are not designed for use on large or spreading fires. Even on small fires they are effective only under certain conditions
Basic Types of Extinguishing Materials
The basic types of extinguishing materials include the following:
• WATER
• CARBON DIOXIDE
• DRY CHEMICAL / MULTIPURPOSE DRY CHEMICAL
• METAL/SAND
• WATER MIST
• HALOTRON
There are various other “specialty” types of extinguishers available that are designed for specific types of hazards.
Water as an Extinguisher of Fire
Advantages
• Removes heat effectively
• Effective on Class A fires (Ordinary Combustibles)
• Inexpensive
• Plentiful
• Non-toxic
Disadvantages:
• Conducts electricity
• May spread Class B fires
• Freezes in cold climates
• May carry pollutants as run-off water
Carbon Dioxide (CO2) as an Extinguisher of Fire
Advantages:
• Reduces oxygen to the fire
• Effective on Class B and C fires (Gases and Electrical)
• Does not leave residue
• Relatively inert
Disadvantages:
• Toxic to humans in quantity
• Not the best agent for smoldering deep-seated fires
• Dissipates rapidly – this may allow for “reflash” of fire
• May have a cooling/chilling effect on some electronic components
Dry Chemical as an Extinguisher of Fire
Advantages
• Interrupts chemical reactions
• Very effective on Class B and C fires
• Not considered toxic
Disadvantages
• Leaves a residue
• May obscure vision
• Not effective for deep-seated Class A fires
• Absorbs moisture and may "cake" within container
• May be irritating to skin/eyes
• Nozzle pressure may cause burning liquids to splash
Multipurpose Dry Chemical as an Extinguisher of Fire
Advantages
• Interrupts chemical reactions
• Effective on Class A, B, and C fires
• Non-conductive
Disadvantages:
• Obscures vision
• More irritating to skin/eyes than ordinary dry chemical
• Nozzle pressure may cause burning liquids to splash
Other Types of Extinguishers
Metal/ Sand Extinguishers
• Metal/Sand Extinguishers are for flammable metals (class D fires) and work by simply smothering the fire with powdered copper metal or sodium chloride. You should have an approved class D extinguisher if you are working with flammable metals.
Water Mist Extinguishers
• Water Mist extinguishers use distilled water which is “misted” on a fire to extinguish it. These extinguishers are ideal for Class A fires where a potential Class C (electrical) hazard exists. Unlike “water” extinguishers, the misting nozzle provides safety from electric shock and reduces the scattering of burning materials. This type of extinguisher is often used in high-tech environments such as labs and hospitals.
Halotron Extinguishers
• Halotron extinguishers can be used on class A, B and C fires. Halotron is an ozone-friendly replacement for Halon that has been banned from use due to environmental reasons. The discharge does not cause thermal or static shock, is non-conducting and does not leave residue. This makes these extinguishers perfect for electronic applications.
Types of Extinguishers
All extinguishers are labeled as to what type of fire they can be used on. On the label you will find a system of letters and symbols to aid in proper use.
In this part of the program we will be examining the “Classes” of fires and the type of extinguisher necessary to combat each one.
Types of Extinguishers
The ABC Extinguisher SymbolsThe AB Extinquisher Symbols
Extinguishers are all “classified” by letters (A,B,C,D) and also have standard symbols on them for easy identification. If there is a red slash through one of the symbols it means it cannot be used on that class of fire.
Ensure that the fire extinguisher you have is appropriate for the potential types of fire being fought. If you use the wrong kind of fire extinguisher, you can easily make a fire worse and endanger yourself and others. For example, using a water extinguisher on an electrical fire will cause shock to the operator, or, using a pressurized extinguishing agent on a grease fire could easily aid in spreading a fire.
Extinguishers also use a number system along with the identifying letters - the larger the number, the larger the fire the extinguisher is capable of putting out.
Multipurpose Fire Extinguishers
Multipurpose fire extinguishers (class ABC) are the most common type and are recommended in most circumstances. They are useful as they can be used on the most common of the major classes of fires.
Extinguishers that are suitable for more than one class of fire are identified by multiple symbols (reviewed in this section of the course) that are placed in a horizontal sequence.
Extinguishers – The Classes of Fire
Fires can be classified into four general categories (Classes):
1. Class A - Ordinary Combustibles
2. Class B - Flammable Liquids, Greases, or Gases
3. Class C - Energized Electrical Equipment
4. Class D - Combustible Metals
Class A Extinguishers
- Class A - Ordinary Combustibles
• Class A fires involve ordinary materials like burning paper, lumber, cardboard, plastics, etc. Ordinary combustibles are extinguished by cooling the material below the ignition temperature and soaking the fibers to prevent re-ignition. Pressurized water, foam or multipurpose (ABC-rated) dry chemical extinguishers are used for this type of fire.
• NEVER use carbon dioxide or ordinary (BC-rated) dry chemical extinguishers on a Class A fire.
• Class A extinguishers are not suitable for burning liquids, electrical fires or reactive metal fires.
Class A Extinguishers
Class A Letter SymbolClass A extinguishers are identified by a triangle containing the letter "A". If coloured, the triangle should be green.
Class B Fires
2. Class B - Flammable Liquids, Greases, or Gases
Class B fires involve flammable or combustible liquids such as gasoline and kerosene. Extinguish these flammable liquids, greases or gases by removing the oxygen, preventing the vapors from reaching the ignition source or inhibiting the chemical chain reaction. Foam, carbon dioxide, ordinary (BC-rated) dry chemical, multipurpose dry chemical, and halon extinguishers can be used to fight Class B fires.
Class B Extinguishers (cont.)
Class B Letter SymbolClass B Extinguishers are identified by a square containing the letter "B." If coloured, the square should be red.
Class B Picture SymbolClass C - Energized Electrical Equipment
3. Class C - Electrical -
Extinguish energized electrical equipment by using an extinguishing agent that is not capable of conducting electrical currents. Carbon dioxide, ordinary (BC-rated) dry chemical, multipurpose dry chemical and halon fire extinguishers are used to fight Class C fires. NEVER use water extinguishers on energized electrical equipment.
Class C fires involve energized electrical equipment, such as appliances, switches, panel boxes, and tools. Water is usually a dangerous extinguishing medium for class C fires because there is a risk of electrical shock.
Class C Extinguishers
Class C Letter SymbolClass C extinguishers are identified by a circle containing the letter "C." If coloured, the circle should be blue.
Class C Picture SynbolClass D - Combustible Metals
4. Class D fires involve combustible metals, such as magnesium, titanium, potassium or sodium. These materials burn at extremely high temperatures and will react violently with water, air, and/or other chemicals.
Class D Extinguishers
Class D extinguishers for fires involving metals are identified by a five point star containing the letter "D." If coloured, the star is yellow.
Extinguishers – Type and Number
You must ensure that you know and understand the potential fire hazards in your workplace, and that you have the appropriate type and number of extinguishers on hand to deal with the fire – before a fire breaks out.
Extinguishers must be tested and listed by The Underwriters' Laboratories of Canada (ULC). Look for the ULC label on the extinguisher.