Why is it called a backdraft?
Due to pressure differences, puffs of smoke are sometimes drawn back into the enclosed space from which they emanated, which is how the term backdraft originated. Backdrafts are very dangerous, often surprising even experienced firefighters.
Why does Backdraft cause corrosion?
Backdrafting can also result in metal corrosion because the condensate, which is acidic by nature, can appear on the top of the heater, where hot gases get in touch with the cold metal elements. If playback doesn't begin shortly, try restarting your device.
What is a downdraft and what causes it?
Downdraft is caused by something called the stack effect, which is when warm air rises, leaving less air closer to the floor. In two-story homes or homes with attics, warm air creates a high-pressure point towards the top of your home.
How does a backdraft fire happen?
How a Backdraft Happens. As explained above, a backdraft is a sudden explosion caused by new oxygen entering a fire’s sphere of influence. Once a fire has consumed all the oxygen it can get, it will begin to dwindle. But a guttering fire is no less dangerous.
What are the signs of backdraft?
Common signs of imminent backdraft include a sudden inrush of air upon an opening into a compartment being created, lack of visible signs of flame (fire above its upper flammability limit), "pulsing" smoke plumes from openings and auto-ignition of hot gases at openings where they mix with oxygen in the surrounding air.
How do you stop backdraft?
Most of the time, this is accomplished by cutting an opening in the roof and refraining from opening any windows or doors on or below the fire floor until conditions have changed. This means that no search and rescue can occur and no water is being put on the fire until the vertical ventilation can be completed.
Why do flashovers occur?
When certain organic materials are heated, they undergo thermal decomposition and release flammable gases. Flashover occurs when the majority of the exposed surfaces in a space are heated to their autoignition temperature and emit flammable gases (see also flash point).
What is the most effective method of preventing backdraft?
The best way for us to prevent this phase from occurring is to ventilate vertically as much as possible when suppressing the fire.
What causes downdraft?
Local daytime heating of the ground causes surface air to become much warmer than the air above, and, because warmer air is less dense, it rises and is replaced by descending cooler air.
How do I stop wind from blowing down my chimney?
A chimney balloon and a flue blocker are two fast and easy solutions. A chimney balloon is placed inside the chimney and is then inflated. It gets rid of the noise, keeps the cold air out and the warm air inside. A flue blocker works in the same way, except it's easier to install than the chimney balloon.
How do you prevent flashovers?
Ways to prevent flashover. By proper ventilation, we can eliminate superheated air and gases from the compartment. Depending on the fire, you can call for a horizontal or vertical vent. Just be conscious of the venting and location of the vent to not get other portions of the uninvolved structure involved.
What does it mean when smoke swirls down?
It's caused by thermal-radiation feedback (also known as re-radiation), which is the energy of the fire and hot gases being radiated to the contents of the room from the heated enclosure surfaces (e.g., upper walls and ceiling).
At what temperature does smoke combust?
They start vaporizing at a temperature of about 300 degrees F (149 degrees Celsius). If the temperature gets high enough, these compounds burst into flame.
What causes downdraft in a chimney?
Downdraft is caused by something called the stack effect, which is when warm air rises, leaving less air closer to the floor. In two-story homes or homes with attics, warm air creates a high-pressure point towards the top of your home. Lower pressure points will attempt to regulate by pulling in air.
When can a backdraft occur?
A backdraft can only occur when there is a hot, fuel-rich fire compartment with a limited air supply, such that the fire becomes highly ventilation-limited or is extinguished, possibly with residual smoldering or hot spots remaining [2].
Where does backdraft occur?
Chicago's ChinatownThe movie takes place in Engine Company No. 17, based in Chicago's Chinatown, where Kurt Russell is the grizzled veteran and William Baldwin is his kid brother, a rookie fresh from the fire academy.
Overview
A backdraft (North American English) or backdraught (British English) is the abrupt burning of superheated gasses in a fire, caused when oxygen rapidly enters a hot, oxygen-depleted environment; for example, when a window or door to an enclosed space is opened or broken. Backdrafts present a serious threat to firefighters. There is some debate concerning whether backdrafts should be c…
Burning
When material is heated enough, it begins to break down into smaller compounds, including hydrogen. This is called pyrolysis, and does not require oxygen. If oxygen is also provided, then the hydrogen can combust, starting a fire.
If material undergoing pyrolysis is later given sufficient oxygen, the hydrogen gas will ignite, and therefore, combustion takes place.
Cause
A backdraft can occur when a compartment fire has little or no ventilation. Due to this, little or no oxygen can flow into the compartment. Then, because fires reduce oxygen, the oxygen concentration decreases. When the oxygen concentration becomes too low to support combustion, some or all of the combustion switches to pyrolysis. However, the hydrogen and smoke (primarily particulate …
Backdrafts and flashovers
Although ISO 13943 defines flashover as "transition to a state of total surface involvement in a fire of combustible materials within an enclosure", a broad definition that embraces several different scenarios, including backdrafts, there is nevertheless considerable disagreement regarding whether or not backdrafts should be properly considered flashovers. The most common use of the term flashover is to describe the near-simultaneous ignition of material caused by heat attai…
In popular culture
Backdrafts were publicized by the 1991 movie Backdraft, in which a serial arsonist in Chicago was using them as a means of assassinating co-conspirators in a scam.
In the film adaptation of Stephen King's 1408, the protagonist Mike Enslin induces one as a last-ditch effort to kill the room.
The term is also used and is the title of a scene in the 2012 video game Root Double: Before Cri…
See also
• Pyrolysis
• Hydrogen
• Combustion
External links
• A backdraft (still image and video) (in Swedish)
• Slow Motion Backdraft video
• White Smoke Warning
• Daniel's Block Fire-BACKDRAFT