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How do fire extinguishers work?

by Submitted to The Dominion Post

All objects in the universe are made up of matter. Matter is made up of elements. Each element has its own characteristics, but all elements are made up of atoms. And atoms are made up of protons, neutrons and electrons. Protons are positively charged. Neutrons do not have a charge. And electrons are negatively charged. The nucleus (or center) of atoms is made up of protons and neutrons packed together. Electrons kind of fly around the nucleus. Atoms are very tiny in general  — the width of a human hair is made up of about 12 million atoms — but they are also made up of a bunch of empty space (for example, a hydrogen atom, which only has one proton, is 99.9999999999996% empty space). So, protons and neutrons are very small compared to an atom. But, electrons are so small that, when the mass of atoms are measured, scientists don’t even take into account the mass of electrons because it can be negated.

Just because electrons are small, does not mean they are unimportant. The atom is neutral if it contains an equal number of electrons and protons. When an atom has more electrons than protons, the atom is negatively charged. This is referred to as a negative ion (aka an anion). And, if an atom has more protons than the electrons, the atom is positively charged. This is referred to as a positive ion (aka a cation). Ionization is the process of an atom/molecule losing/ gaining electrons. 

Before the idea of the periodic table of elements was developed, people thought the world was made up of four elements: Air, water, earth, and fire (ATLA flashbacks, anyone?). Once it was discovered that there were hundreds of elements that made up the world, it was also discovered that fire was made up of some of these elements as well.

Fire is made up of a bunch of different gases. Chemical reactions between oxygen and a fuel — for example, wood or propane — produce carbon dioxide, steam, light and heat. If the flames (visible portion of the fire) become hot enough, the gases in the fire become ionized.

You might be familiar with the three common states of matter: Solid (the atoms in the object are packed together), liquid (the atoms in the object are together but move around a bit), and gas (the atoms are free to travel around). There are two more states of matter as well: Bose-Einstein condensate and plasma.

Scientists Eric Cornell and Carl Weimann cooled a sample of rubidium (which has 37 protons and, hence, is the 37th element on the periodic table of elements) to a temperature that is very close to 0 Kelvin. Zero Kelvin is about -459.67 degrees Fahrenheit. Every single object, no matter the temperature, is supposed to have kinetic energy. This means that the atoms inside every single object have to be moving at least a little bit. But, the theory is that at 0 Kelvin, the atom doesn’t have kinetic energy at all. No object can be cooled to 0 Kelvin, because this is impossible. This is why 0 Kelvin is called absolute zero. When Cornell and Weimann cooled rubidium to almost absolute zero, they created a new state of matter called Bose-Einstein condensate, in which the kinetic energy of the object was almost 0 and it resembled a “super atom.” This state of matter is not natural.

Plasma, the fifth state of matter, however, is natural. Although plasma isn’t common on Earth, it is the most common state of matter in the universe. Plasma is made up of highly charged particles with really high kinetic energy. Noble gases, which are helium, neon, argon, krypton, xenon and radon, can be ionized to the point that their state of matter switches to plasma to help make glowing signs. Fire’s state of matter is mostly gas and a little bit of plasma.

We can look at fire as three components: Heat, oxygen and fuel. To get rid of a fire, we must eliminate at least one of these components, which is a fire extinguisher’s job. In a fire extinguisher, there is a plastic syphon tube that is connected to the top of the fire extinguisher to almost the bottom. A spring valve near the syphon blocks a passageway from the syphon to the nozzle. There is also carbon dioxide in the cylinder connected to the top of the fire extinguisher. When you press down on the operating lever, there is a sharp rod that makes a hole in the cylinder where the carbon dioxide is. This opens the passageway so that carbon dioxide is released and the fire suppressant that is in the fire extinguisher travels up the syphon and out of the extinguisher.

Another type of extinguisher is the water extinguisher. This is actually the most common type of extinguisher. Water extinguishers are just tanks full of water. They remove the heat component of the fire and they also help eliminate the oxygen component of the fire.

In restaurants, you can find carbon dioxide extinguishers. These extinguishers release carbon dioxide and, since it is heavier than oxygen, it will push down on the oxygen which will get rid of the oxygen component.

A third type of extinguisher is the dry powder extinguisher, which is a tank of dry powder. The powder is supposed to absorb heat, melt and coat the fuel, which blocks out the oxygen. This means it takes out the heat  and the oxygen components of the fire.

And the fourth type of extinguisher is the foam extinguisher. Foam extinguishers are tanks of water and foam and work by smothering the fire. Spreading foam over a fire cuts the fuel off and absorbs heat (getting rid of the fuel and heat components of the fire).

There are five classifiers for fire extinguishers: A is for wood, cloth, and papers, B is for combustible and flammable liquids (i.e. oil, gasoline and paint), C is for electrical equipment and tools, D is for flammable metals, and K is for animal or vegetable oils, or cooking fats.

Please make sure you use the correct fire extinguisher for the fire you are trying to extinguish. To correctly use a fire extinguisher, you need to aim the fire extinguisher at the base of the fire and spray it in a sweeping motion.

 Vaageesha Das is a junior at Morgantown High School. 

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