Ventilation removes smoke and hot gases from a burning structure. It is utilized in several scenarios, including fire control, fire attack, overhaul, and search and rescue. Firefighters can use basic ventilation procedures to address many fire hazards.
The goal of firefighting is to stop a fire from spreading horizontally, especially for attic and balloon construction fires. While attic flames are usually too hazardous to vent, balloon fires can benefit from early vertical ventilation. Fires that start in the walls of balloon frame buildings will soon spread to the attic and throughout the building. The consequences of a fire spread decrease if vertical vents are installed early in the attempt to suppress the fire.
Ventilating fires reduces the risk of injury or death to civilians and firefighters. A flashover, the most dangerous type of fire, must be avoided at all costs. A flashover can happen when the majority of the immediately exposed flammable material in a confined area ignites almost simultaneously. Vertical ventilation eliminates heat from a confined space, minimizing the chances of a flashover, and increases visibility to help firefighters inside a building search quickly and, in turn, lower the risk of crews being lost or disoriented.
Vertical ventilation removes harmful gases and smoke by enabling them to flow upwards. This method is an effective technique that has been used by firefighters for over a century, proving itself in countless situations.
The benefit of vertical ventilation is due to fire behavior, as because of convection, heat travels straight up. Vertical ventilation facilitates this natural flow and is, therefore, the most effective at clearing an interior space of smoke. It also lowers, prevents, or stops gas and smoke mushrooming, making interiors safer. In a one-story single-family home, for instance, the results are immediate.
A vent crew, usually composed of two firefighters, starts the vertical ventilation process by removing any existing vents or chimneys in the affected structure. If this isn’t enough to improve ventilation, an opening must be created.
To make the vertical vents, the firefighters use cutting gear, ladders, a charged hose line, and two escape routes. They make cuts in the roof as close to the flames as possible and punch out the ceiling. After completing the cutting and venting, the firefighters leave the roof and return to safety.
Vertical ventilation has its drawbacks. First, firefighters face the risk of being on top of a burning building. These include structure collapse, confusion, and falls.
Second, vertical ventilation is time-consuming for roofs that are difficult to penetrate. Third, floors not at the top of a building may receive minimal benefit. Finally, vertical ventilation requires resources that some departments may lack.
Departments with enough staff may combine vertical ventilation with other methods. Departments with minimal employees may need to use less labor-intensive methods such as negative pressure ventilation and hydraulic ventilation. The former uses smoke ejectors to eliminate smoke from a building, while the latter uses a hose line to direct smoke and hot gases out of the windows.
from WordPress https://ift.tt/3Bw8a8Z
via IFTTT
