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LO 6-9 Describe the various types of fire suppression systems and explain their use

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Course: DE Section 2-1: Engine Blocks and Cylinder Heads
Book: LO 6-9 Describe the various types of fire suppression systems and explain their use
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Date: Thursday, 5 November 2026, 7:44 PM

Table of contents

1. Fire Prevention

LO 6-09: Describe the various types of fire suppression systems and explain their use.

 

Fire Prevention

When working with flammable fuels or gases, it is essential to take all the necessary precautions to prevent fires. Always notify those around you that you are working with flammable materials and have the correct type of fire suppression equipment close at hand. Use LED or fluorescent trouble lights that are battery powered to reduce the risk of the light breaking and becoming an ignition source Figure 36. When working with any type of flammable material, make sure that spills are cleaned up immediately and that there are no potential ignition sources or activities nearby that could ignite flammable liquids.

  Technicians Tip  
  Fuel vapor is impossible to see, and different fuels can vaporize and form combustible mixtures at varying temperatures. Gasoline, for example, easily vaporizes at room temperature and very quickly forms a combustible mixture with air. If small quantities of gasoline are mixed with diesel fuel, any fuel can allow vapors to spread far from the original spill area and make contact with an ignition source.  
  Fig06_36

FIGURE 06-36: LED trouble lights are safer to use than incandescent bulb types.

 

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1.1. Video: Fire Extinguishers

LO 6-09 Video: Fire Extinguishers

 

 

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1.2. Fire Suppression

LO 6-09: Describe the various types of fire suppression systems and explain their use.

 

Fire Suppression

A fire requires three elements to form: something burnable (fuel), sufficient oxygen (the reactant), and a source of heat (or ignition). If any of the three elements is removed, the fire stops. In fire suppression, the idea is to remove one or more of the elements, usually the oxygen. When dealing with fires, always remember that you are not a trained firefighter; you are a service technician. If the fire is significant, the first thing to do is remove yourself from the situation and call emergency services to extinguish the fire. Fire extinguisher locations should be marked as in Figure 37.

 

   Fig06_37

FIGURE 06-37: Fire extinguisher locations should have correct signage that is easily visible.

 

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1.3. Classification of Fires

LO 6-09: Describe the various types of fire suppression systems and explain their use.

 

Classification of Fires

In North America, fires are classified into five different types by letter:

  • Class A: These are fires in which the combustibles are burning, such as paper, wood, or cloth.
  • Class B: These are fires that involve flammable liquids or gases.
  • Class C: These fires involve electrical equipment.
  • Class D: These fires involve combustible metals, such as magnesium, lithium, sodium, or titanium.
  • Class K: These are fires in which cooking oil or fat is burning.

 

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1.4. Fire Extinguisher Types

LO 6-09: Describe the various types of fire suppression systems and explain their use.

 

Fire Extinguisher Types

Fire extinguishers are rated by which type of fire they are suitable for: A, B, C, D, or K. There are pictograms (a small image depicting the type of burning material the fire extinguisher is recommended for) on the fire extinguisher. A letter in the pictogram also indicates the class of fire for which the extinguisher is suitable. Fire extinguishers can contain carbon dioxide, water, dry chemical, or foam. Most types of fire extinguishers are combination extinguishers capable of fighting or suppressing more than one class of fire. The most common fire extinguisher found in a commercial vehicle service facility is a combination ABC fire extinguisher Figure 38.

An ABC fire extinguisher is capable of fighting Class A, B, and C fires. An ABC fire extinguisher has three pictograms side by side showing the type of material for which the fire extinguisher is used. An ABC fire extinguisher is a dry chemical extinguisher that works by starving the fire of oxygen. There are specialized fire extinguishers for certain workplaces where other types of fires are possible or likely. These fire extinguishers may contain foam, water, wet chemicals, or inert gases. Note that battery electric vehicles will use a Class K extinguisher for fires originating in a battery.

Fire extinguishers must be inspected and certified by a registered specialist, usually on an annual basis. An inspector tags the fire extinguisher with the name of the inspector, the company performing the service, and the date of the last inspection Figure 39. The fire extinguishers should also be checked by the Joint Health and Safety Committee during each shop safety inspection, making sure the seal is intact and the pressure reading is in the normal range.

  Fig06_38

FIGURE 06-38: An ABC combination fire extinguisher.

   Fig06_39

FIGURE 06-39: A fire extinguisher inspection tag.

  

 

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1.5. Operation of a Fire Extinguisher

LO 6-09: Describe the various types of fire suppression systems and explain their use.

 

Operation of a Fire Extinguisher

Before attempting to use a fire extinguisher on a fire, alert your supervisor or a coworker to the presence of a fire and that you are trying to extinguish it. Position yourself between the fire and an exit. Do not let the fire block your escape! Assess the fire and verify that you have the correct fire extinguisher for the fire class (using a water-based Class A fire extinguisher on a flammable liquid fire causes the fire to spread or even explode). Instructions for proper use are typically displayed on the fire extinguisher Figure 40.

Most fire extinguishers have a hose attached. If so, hold the fire extinguisher in one hand by the handle. Pull the pin and grasp the hose with the other hand. Squeeze the handle while aiming the hose and nozzle at the base of the fire, not at the flames. Use a side-to-side sweeping motion; if your efforts are having little or no effect, cease immediately and evacuate. When you are safely away from the fire, call emergency services. If you are successful and put the fire out, be very careful that it does not start again. Remove the fuel and/or the source of ignition and monitor the area to be sure that the fire is out. To correctly use a fire extinguisher, follow the steps in Skill Drill 6-3.

   Fig06_40

FIGURE 06-40: Instructions for proper use are typically displayed on the fire extinguisher.

 

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1.6. SKILL DRILL 6-3  Using a Fire Extinguisher

SKILL DRILL 6-3  Using a Fire Extinguisher

 

STEP 1
Assess the fire to ensure that you have the correct fire extinguisher for the fire class. Stand 10' (3 m) back from the fire. Grasp the fire extinguisher by the handle and pull the pin.

STEP 2
Grasp the hose (if equipped) in your other hand and point the hose or nozzle of the fire extinguisher at the base of the fire, NOT at the flames.

STEP 3
Squeeze the handle to discharge the fire extinguisher.

STEP 4
Use a side-to-side sweeping motion as you discharge the fire extinguisher at the fire.

STEP 5
If your efforts are unsuccessful, immediately evacuate the area. Only when you are safely clear of the danger area, call emergency services. If you are successful, continue to monitor the fire to ensure that it does not restart.

 

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