Firefighters extinguish fires, right? Sure. But first they need to control them. That means controlling heat and smoke — and that means ventilation.
How does ventilation affect a fire? It opens paths for smoke and heat to leave rather than collect in a burning building. Buildings where smoke and heat have been reduced by venting a roof during a fire are easier to safely assess and attack. Trapped citizens can survive longer waiting for rescue, and interior crews can move quicker with less chance of becoming disoriented.
Why Ventilation After a Fire Is Important
Flashover is one of the greatest dangers faced by firefighters. It occurs when trapped smoked exponentially raises the heat in an enclosed area, causing the spontaneous and simultaneous ignition of combustible materials in that area.
One of the most effective ways to avoid flashover is by venting a fire. That’s why ventilation should be at the top of every fire scene’s to-do list.
Of course, not all scenes are the same. Priorities must be assessed based on individual factors, but the longer ventilation is put off, the more dangerous it becomes. Never let ventilation be an afterthought.
Know Your Smoke
Modern firefighting uses technologies to ventilate after a fire such as thermal imaging cameras (TIC) and positive pressure ventilation (PPV) fans that help firefighters determine vent locations upon arrival at a fire scene and speed smoke removal once the fire is struck. However, technology shouldn’t be a substitute for honed observational skills.
Firefighters must know how to read smoke in order understand and manipulate a fire. Remember:
- Rapidly rising smoke is ready to ignite.
- Darker, richer smoke is more laden with fuel and is close to the fire.
- Smoke further from the point of origin will be lighter in color.
Vertical ventilation is a proven way to fight fires. Essentially, it amounts to cutting holes in the roof of a burning structure to allow super-heated gases and smoke to continue their natural upward path.
Firefighters venting a roof make it easier for their comrades to safely enter and navigate through a building to attack the fire within. However, not all firefighter roof ventilation cuts are created equal.
Consider that many pitched roofs now have ridge vents, and thus no ridge board. Instead of making horizontal cuts through rafters and vertical cuts to cut a square out of a roof, you can start at the ridge and simply make parallel vertical cuts one foot apart between rafters to more quickly make larger holes. Each sheet of roof decking provides its own horizontal cuts.
For added safety, remember:
- Use roof ladders (to provide stability on steep roofs and spread load on all roofs) wherever possible.
- The strongest areas of a roof are the ridges and valleys.
- When sounding the roof, use a roof hook or other long tool to strike the roof. Striking or tapping the roof with a shorter implement — or worse, a boot — will put you directly over compromised portions of a structure.
Also remember that ventilation is rarely accomplished without also punching through the ceiling. Pick the tool for this job based on the pitch of the roof and thus the height of the attic space.
Should You Ventilate With PPV?
Why do firefighters vent the roof? They need to speed the release of deadly smoke and heat. The temptation of further hastening that release with fans, however, should be avoided. Used incorrectly, PPV can add fuel to a fire. Simply, PPV is best used for post-fire ventilation.
Let Us Move Your Air
Still, it is important to have the tools to effectively move air, no matter the fire scene. Balancing portability, adaptability, power, toughness and run time, choose from among the three Blowhard portable smoke ventilation fans to find the products that best suit your needs.