Fire

Fire Suppression: Techniques, Strategies, and Challenges

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OBJECTIVES

Upon completion of this lesson, you will be able to:

  • Describe fire suppression and its importance for firefighters.
  • Explain offensive Vs. defensive firefighting techniques.
  • Describe the Specific fire ground operations and associated hazards of them.
  • Describe the management of specific fire ground operations.

Firefighter using fire pump system with high-pressure hose

1 Introduction

The term “fire suppression” refers to all of the tactics and tasks that are performed on the fire scene to achieve the final goal of extinguishing the fire. Fire suppression can be accomplished through a variety of methods that will stop the combustion process. All these methods involve removal of one of the four components of the fire tetrahedron-that is, a fire can be extinguished.

2 Offensive Vs. Defensive Operations

Interior Fire Attack

It is an offensive operation that requires firefighters to enter a building and discharge an extinguishing agent onto the fire. An interior structure fire is a fire that occurs inside the building. Its fuel could be the contents of the building, or the structure itself might be burning. The larger the fire, the greater the challenge in suppressing it, and the more ominous the risks that are involved in interior fire suppression.

Direct Attack

The most effective means of fire suppression in most situations is a direct attack. This kind of attack uses a straight or solid hose stream to deliver water directly onto the base of the fire.

Indirect Attack

Indirect application of water is used in situations where the temperature is increasing and it appears that the room or space is ready for flashover. In this method, the fire fighter aims a short burst of water at the ceiling to cool the superheated gases in the upper level of the room or the space.

Combination Attack

This strategy should be used when a room’s interior has been heated to the point that it is nearing a flashover condition. First use an indirect attack method to cool the fire gases. Firefighters who operate the nozzle should be given plenty of space to maneuver.

Protecting Exposures

Actions that are taken to prevent the spread of a fire to areas that are not already burning. Exposure protection is consideration at every fire; it becomes even more important with a large fire. If the fire is relatively small and contained within a limited area.

Specific Fire Ground Operations

Concealed-Space Fires

Fires in ordinary and wood-frame construction can burn in combustible void spaces behind walls and under subfloors and ceilings. To prevent the fire from spreading, these fires must be located and suppressed behind walls and under subfloors.

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Basement Fire

Fires in basements or below grade level present several different challenges and have limited routes of egress. Difficult to recognize the exact seat of fire, and it can damage the floor above the fire.

  • Fire fighters are at risk of failing through the damaged floor and ending up in the burning basement.
  • Fire fighters may find it hard to see in the basement. It is difficult to remove the fire gases and steam produced by the attack lines.
  • Challenging to keep their sense of orientation for fire fighters.
  • If the only point of entry is an interior stairway, fire fighters must protect that opening so ventilation must be conducted early.

Fire Above Ground Level

  • Advancing charged hose lines upstairs and along narrow hallways requires much more physical effort than advancing a charged hose line on a level surface.
  • It is important to protect stairways and other vertical openings between floors when fighting a fire in a multiple-level structure.
  • When working with a hose above the ground floor, fire fighters should advance the line uncharged until they reach the fire floor and have extra hose available.
  • Interior fire crews must always look for a secondary exit path. This secondary exit could be a second interior stairway, an outside fire escape, a ground ladder placed to a window, or an aerial device.

Fire in Large Building

  • Large buildings such as “big box” stores or office buildings contain one very large open space surrounded by smaller rooms and storage areas.
  • When these structures experience fires, the fire lead varies greatly depending on the building contents.
  • “Big box” stores and home improvement centers contain large amounts of flammable materials ranging from lumber to flammable fuels.
  • Many large buildings have floor plans that can cause firefighters to become lost or disoriented while working inside, particularly in low-visibility or zero-visibility conditions.
  • Consider the need for long hose lays when fighting a fire in a large building if an adequate number of standpipe connections are not available.

Fire in Buildings During Construction, Renovation, or Demolition

  • Have increased risk for destruction by fire.
  • Often have large quantities of combustible materials exposed, while lacking the fire-resistant features of a finished building.
  • If the building lacks windows and doors, an almost unlimited supply of oxygen is available to fuel a fire.
  • Building protection systems are often not installed.
  • If no life-safety hazards are involved, fire fighters may need to use a defensive strategy and no fire fighters should enter the building, and a collapse zone should be established.
  • A defensive exterior operation should be conducted using master streams, aerial streams, and large hand lines to protect exposures.
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Fire in Lumberyards

Lumberyard fires are often prime candidates for a defensive firefighting strategy.

  • It contains large quantities of highly combustible material that are stored in the open or in sheds where plenty of air is available.
  • Given this rich fuel supply, a lumberyard fire will usually produce tremendous quantities of radiant heat and release burning embers that will cause the fire to spread quickly from stack to stack.
  • Protecting exposure is often the primary objective, as there may be little life safety risk.
  • Exposure protection should be dealt with early in the operation by placing large hand lines and master stream devices.
  • A collapse zone must be established around any stacks of burning material and buildings to keep firefighters out of dangerous positions.

Fire in Stacked or Piled Materials

Fires occurring in stacked or piled materials can present a variety of hazards, such as:

  • A stack of heavy material, such as rolled paper or baled rags, will collapse without warning.
  • A tall stack of material that falls on top of a team of firefighters can cause injury or death, so fires in stacked materials should be approached cautiously.
  • Mechanical equipment should be used to move material that has been partially burned or water-soaked.
  • Class A foam wetting agents can be applied to extinguish smoldering fires in tightly packed combustible materials. Overall, firefighters will need to separate the materials to expose any remaining deep-seated fire.

Trash Container and Rubbish Fires

These fires usually occur outside of any structure and appear to present fewer challenges than fires inside buildings. Even so, firefighters must be vigilant in wearing full PPE and using SCBA when fighting trash container fires or trash pile fires, because there is no way of knowing what might be included in a collection of trash.

  • Some trash containers may contain hazardous materials or highly flammable or explosive. Therefore, manual overall involves pulling the contents of a trash container apart with pike poles and other hand tools so that water can reach the burning material.
  • The firefighters are exposed to any contaminants in the container as well as to the risks of injury from burn smoke, or other causes.
  • Class A foam is useful for extinguishing many trash container fires, because it allows water to soak into the materials and therefore, can eliminate the need for manual overhaul.

Vehicle Fire

Vehicle fires are one of the most common types of fires handled by fire departments. These fires may result from a variety of causes; for example, electrical short-circuit, friction, and collisions, etc. Hazards associated with vehicle fires are traffic hazards, fuel pressurized cylinders & containers, fire & toxic smoke, etc.

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Attacking Vehicle Fires

  • Create a safe area around the vehicle. The only people closer than 50 feet to the vehicle should be firefighters in full PPE and SCBA.
  • Use a hose line at least 1 ½ inches in diameter; such a hose will provide sufficient cooling power to overcome the fire and provide protection from a sudden flare-up.
  • Use Class B foam for fire suppression. Charge the hose line while you are at least 50 feet from the fire, bleed all the air from the hose line, and set the nozzle to initially deliver a straight stream or a fog pattern that is no wider than a 30-degree angle.
  • Approach the vehicle from an uphill and upwind position, this path will help you avoid debris in case of an exploding bumper.
  • At the distance of 30 feet from the vehicle, open the nozzle and sweep the bottom part of the vehicle using a horizontal motion.
  • Extinguish all visible fire while advancing toward the vehicle. Observe the area under the car during the approach for any sign of leaking flammable liquids. If burning flammable liquids are present, widen the spray pattern on the nozzle. Foam can be used to extinguish the burning liquids.

Electrical Fire Suppression

  • Fire suppression methods vary according to the type of equipment and the power supply. The best approach is to wait until the power is disconnected and then use the appropriate extinguishing agents to control the fire.
  • If the power cannot be disconnected or the situation requires immediate action, only Halon agents, CO2, or dry chemicals should be used. If power distribution lines or transformers are involved, special care must be taken to ensure the safety.
  • Many electrical transformers contain a cooling liquid that includes polychlorinated biphenyls, a cancer-causing material. Do not apply water to a burning transformer because water can cause the transformer’s cooling liquid to spill or splash, contaminating both fire fighters and the environment.
  • If the transformer is located on a pole. It should be allowed to burn until electrical utility professionals arrive and disconnect the power.
  • Fires in ground mounted transformers can also be extinguished with dry chemical agents after the power has been disconnected.
  •  Fire fighters should stay out of the smoke and away from any liquids that are discharged from a transformer, and they must wear full PPE and SCBA to attack the fire.
  • Foam may apply only after the power has been disconnected.

 

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