Air contains about 21 percent oxygen, and most fires require at least 16 percent oxygen content to burn. Oxygen supports the chemical processes that occur during fire. When fuel burns, it reacts with oxygen from the surrounding air, releasing heat and generating combustion products gases, smoke, embers, etc. This process is known as oxidation. Remember, OnlyYou can prevent wildfires! Smokey Bear logo. Search Search Text Search Close. Facebook Twitter Close. Oxygen alone won't combust without a spark.
But they do have to be careful about keeping sparks away -- the "no smoking" signs in hospitals aren't just for preventing lung cancer. Like many highly exothermic reactions , the combustion of oxygen has an activation energy --there needs to be an initial bit of energy introduced to the system to get the reaction going. Happy breathing,. That is an excellent question, and the answer is complicated. Air will never spontaneously combust, nor can it be made to burn non-spontaneously.
Air is mostly nitrogen, which is not flammable. Nitrogen is also non-reactive in general, so it doesn't support the combustion of other materials, either. After nitrogen, the most abundant gas in our air is oxygen. Should You Be Worried? It is well known that in order for fire to occur, it takes three elements called the fire triangle. Firefighters know that in order to stifle put out a fire, you must remove one or more of the three elements.
If you were to smother the fire, hence removing the oxygen, it would eventually burn out. But if you remove the blanket too soon, the remaining heat would find more oxygen and reignite. The presence of oxygen in an area that is sufficiently heated, will cause a fire to become supported by the oxygen, but it is not burning; otherwise, we would call it fuel. To complicate matters slightly, firefighters and scientists add a fourth dimension to the fire triangle, called the fire tetrahedron.
A tetrahedron is a four-sided triangle which in this case adds a fourth element to the fire triangle. Free radicals are combinations of many flammable elements which also exacerbate the combustion process. Among other techniques, they can be eliminated by a layer of dry chemical agents. The removal of free radicals can easily be accomplished in smaller fires. The production of smoke and its various elements call for large quantities of water, and effective application.
Oxygen gases and other components of combustion make fire more difficult to extinguish in these large fires, but once the job is done, respiratory issues cease to be a factor. It should be noted that, as long as a fire is still smoldering and is emitting products of combustion, you can still be breathing lots of poisonous gases, free radicals and breathing apparatus SCBA must still be worn.
Also read: Is Carbon Dioxide Flammable? Yes and No…. Liquid oxygen is simply regular oxygen that is compressed from a gas into a liquid. This high pressure causes that change in form. Like all oxygen, LOx will accelerate combustion , but it is not a fuel and is not flammable. Because it is stored in such a concentrated form, LOx can cause a fire to violently increase in size and temperature. While it is not technically flammable, it should be treated with extreme care and safety.
This concept of oxidizer, not fuel is shown well in this video:. Firefighters should know where liquid oxygen tanks are located within their jurisdiction.
LOx storage tanks are commonly found around hospital and healthcare properties. It is also a useful commodity in many other industrial areas that firefighters should be aware of in their district.
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