New Fire Fighting Techniques: Fire Fighting Wand

In 2011 , the American Times magazine selected the top 50 inventions of the year , and the fire-fighting wand was selected as the 27th item. Although it sounds sinister, the principle is rather simple. I just wonder why the predecessors did not pursue their dreams. Why is the United States again? Why was the invention of 2011 , not the invention of 1893 (Chicago World Expo, electrical products exhibition, now the main electrical products, all appeared at the time)? For the electrical theory, the author seems to understand and understand. For the principle of fire extinguishing, the author still has a long-term thinking input, and can understand the phenomenon of extinguishment of the electric wand from the change of the flame structure (the wand is an outsider's statement, producing a movable electric field, used to drive The ions in the flame, which is the key to the extinguishing of the electric stick).

Normally we call the flame, premixed flame and diffusion flame. Premixed flames have high combustion temperatures and high efficiency, but they also have a high risk of use (danger of detonation and explosion). Usually civilian fires, mainly diffusion flames, that is, the contact of fuel and oxygen is carried out by diffusion after the flame has occurred. The key is to require temperature to maintain the continuous combustion reaction. Usually the energy of the fuel is stored in the form of chemical energy in the fuel. The fuel needs to be heated and gasified. The fuel in the gas phase is heated to the combustion temperature, and it is possible to release the energy continuously to maintain the reaction. The reaction zone of the flame is very fine, usually in millimeters or even in the micron range. The flame we see is actually the result of the radiation of smoke from the combustion products and is not the real reaction zone. The real reaction zone is very thin and very hot so that the combustion reaction can be maintained. How much temperature can you keep burning? The ignition diffusion flame requires 1600K ( 1300 degrees Celsius ) to be ignited. The premixed flame at the time of the fire extinguishing needs to reduce the flame temperature to about 1800K ( 1500 degrees Celsius ) to ensure the effectiveness of the fire extinguishing.

How can we extinguish? There are two main fire-fighting methods. One is to stop the supply of fuel from the source, such as using water to extinguish the fire, reduce the surface temperature of the fuel, and stop the pyrolysis process that evaporates and volatilizes. About 80% of the fire extinguishing market is based on the principle of water-based cooling. . Another way is to make an essay on the flame structure. The so-called gas-phase fire extinguishing method has only 20% of the market share, which is also the most profitable market share. The reason is that the gas phase fire extinguishing method does not have pollution, and does not require post-treatment. Once the fire extinguishing can be resumed immediately, it can avoid the production loss caused by conventional fire extinguishing methods. Therefore, although non-water fire extinguishing systems are many times more expensive than water sprinkler systems, there are still a number of wealthy companies that install gas extinguishing systems. I once designed a gas extinguishing system ( FE13/HFC23 ) for McMurdo Scientific Research Base in Antarctica . Why does the South Pole need gas? Because the water will freeze. Why do you need an expensive system? Because it is too far away from the manufacturer, the loss of stop production is too expensive or unacceptable. The cost of transportation from the United States to the South Pole may exceed the equipment itself, so the reliability of the equipment is very high, and this is the advantage of the gas fire extinguishing system. Gas fire extinguishing systems guarantee the normal operation of other equipment.

So, what principle does the fire fighting wand work on? By controlling and driving the ions in the flame, the structure of the flame can be changed. If the flame is thick, it means that the heat dissipation increases and the combustion cannot be maintained. The flame can also be quenched if a thermally conductive object is added to the flame. Halon products can achieve an increased flame threshold through so-called ion capture, making the flame difficult to maintain. And the electric stick? Also through the control of ions, to change the heat dissipation structure of the flame, resulting in the flame can not maintain the normal flame temperature, had to extinguish. In other words, the flame is extinguished by air and fuel (well, the fuel is also of good quality; if it has quality, it absorbs heat and can be considered as a fire extinguishing potential. Of course, the heat-proof potential of the fuel is greater than the fire extinguishing potential. This is a relative contribution. Absolute contribution. It is the fuel that has two potentials, and the fire extinguishing agent only absorbs heat, does not protect against heat, and has a single function. Extinguishing the fire is just a competition between the exothermic and endothermic potential.) The function of the electric cane is to regulate the temperature threshold of the flame. It is difficult to satisfy the originally relatively easy reaction conditions.

I think that the developer's application field seems to be designed as a firefighter's fire-extinguishing tool. This kind of scientific research idea is very wrong. Because the electricity stick itself does not absorb heat, its job is to achieve the fire extinguishing effect by changing the combustion conditions. However, the fuel after the extinguishing still exists, and the gas fuel in the premixed form is in danger of exploding. Therefore, the idea of ​​using the electric stick as a fire extinguishing tool seems to have a technical and ethical dilemma. In my opinion, the best use case for electric rods should be electrical fires, and they should also be treated in their own way. The best place for fire extinguishing is electrical fires, which may have a great impact on Class C fires. In other words, those databases, exchange centers, and reference rooms are most likely to use electronic fire extinguishing systems. This is the most profitable fire extinguishing market. Harvard University's design can only achieve better economic benefits in this area.

In the field of high-profit gas extinguishing, China is the largest beneficiary country of the Montreal Treaty. It has developed in the fire-extinguishing market through the technological transfer of Western countries and the preferential conditions brought about by the status of developing countries. However, the consequences of protection are that there is little research on new fire extinguishing agents in China and there is basically no previous market investment. The high-end fire-extinguishing agent market has given away to people, and the bottom extinguishing agent market is highly competitive. When a revolutionary product emerges from the market, we stop the fight and spot the goal of investing in scientific research. Since the perfect replacement for halon products could not be found, the US fire-extinguishing market was divided by dozens of fire extinguishing agents, and the battle was endless. This kind of electric stick extinguishing technology, if applied in the high-end Class C fire extinguishing field, may have the effect of expelling all extinguishing agents and dominating the rivers and lakes due to its environmental protection effect. It is true that the market is driven by technology, but the fire extinguishing agent market is more dependent on comprehensive considerations of politics and technology. In particular, people are so concerned about the environment today that revolutionary products will surely subvert all traditional understandings. This is what the author stands for as an observer. The feelings of the person.

There is a saying: The electric stick is simple and miraculous. It burns the mystery of understanding the original; the revolutionary technology has just emerged, subverting the opportunity of the market. The batch is: It's time to wait.

The electric field changes the structure of the flame, causing local fire extinguishing, while the fuel continues to react elsewhere. It appears that the flame was driven away by the wand.

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A team of Whiteside researchers at Harvard University developed a new type of fire extinguishing device that was vividly called the "wand." The main component of this device is an electrode designed to reduce the fire and extinguish the flame. Ludovico - Katmatiri, who participated in the study , stated: "It is not changing magic." The "wand" can form an electric field that produces a stream of charged particles that fights fire. This device can not only reduce the damage caused by fire, but also reduce the amount of fire extinguishing water.

The fire extinguishing device developed by the Whiteside Research team at Harvard University creates an electric field that produces a stream of charged particles that fights the flame. In a recent experiment at Harvard, an electric field pushed the flame away from the burner.

Recent experiments have shown that an electric wand allows future firefighters to extinguish a fire with a single stroke of their hand. At present, firefighters use water, foam, powder and other substances to extinguish fire. However, a team of researchers at Harvard University 's research team led by Whitesides pointed out that electric fields can also extinguish fires — reducing water damage and the environmental threat posed by flame retardants. Scientists used a thin wire to connect a 600 watt amplifier—the power of a group of high-end car stereos, the size of which is the size of a file cabinet—inserted into a wall.   The "wand" system generates an electric field with a strength of 1000 kilowatts per meter , "about the electric field strength that inevitably generates sparks in dry air," said Harvard postdoctoral chemist Ludovico Cademartiri .

Whenever the researchers moved the electric wand close to a small flame that fired up to 20 feet (50 centimeters ) , the fire was extinguished almost immediately.

Although it has Harry Potter's energy, it is said that fighting a wand is quite safe. Its frequency, voltage, and current "are not enough to cause health problems for healthy people," Cademartiri explained. The future model will be more complete. An electric wand can be used with only one-tenth of the experimental power. Cadematrii speculates that the magic wand system made in the future may be portable.

How the wand works

The electrons, ions, and smoke in the flame are all affected by the electric field. Based on this principle, the electric wand in the experiment essentially uses electricity to push the fire out of the burner, “separate it from the fuel, and then the fire goes out.” Now, scientists hope to change the shape of the electrode, current, and frequency And voltage, to expand the scope of fire extinguishing magic wand. Cademartiri said: "We have only recently begun to study potential expansion." He imagined that similar devices could eventually be installed on ceilings or ships in buildings, like current sprinkler systems, or on shoulders that could be carried by firefighters.

However, wands are not a panacea, he added. Because the tool is used for indoor fire extinguishing in the future, electric wands do not function well in forest fires and other large-scale fires, he said. “We see that the magnitude of its effect depends on the strength of the electric field,” he explained. “Making a huge electric field over a large area is a challenge.” In addition to extinguishing fires, electric wands are suitable for controlling fire at critical moments, such as engines, furnaces, and torches. . The researchers found that this is because the electric field will also affect the flame temperature and the location of the flicker. “Look for new ways to influence and control the fire,” Cademartiri said. “It may have an impact on a wider area of ​​science and technology.” The study found that this is because the electric field also affects the temperature of the flame, the temperature at which the flame flickers. Card Maddi said, “Finding new ways to influence and control the flames may need to be solved with multiple technologies. “

Recent experimental studies have shown that electric wands allow future firefighters to extinguish flames with a single wave of their hand. At present, firefighters use water, foam and powder to extinguish the flames. But the team of researchers led by Whitesides of Harvard University pointed out that electric fields are very likely to be used to extinguish flames, and the dangers caused by water and the environmental impact caused by fire extinguishing agents can be reduced. The scientists connected a thin wire to a 600 watt amplifier -- power roughly the size of a high-end car stereo, roughly the size of a folder -- and tuck it into a wall. Electric wand system can generate an electric field strength of one million volts per meter, "roughly equivalent to generate an electric field intensity spark in dry air," Harvard University postdoctoral chemist Ludovico Card Mady says. When long as the electric wand nearly burn a height of 20? Track? / Span> 50 cm) of the flame, the flame was extinguished almost immediately. And it is said that electric wands are quite safe. Its frequency, voltage and current "are not enough to cause health problems for healthy people," said Cadmati. Future electric wands may be more gentle. Experimental electric power wand uses only one-tenth of the shop, the wand can achieve almost the same result, Card Madi in speculation - made portable wand system may at some future time. How does an electric wand work? The electrons in the flame, the ions, and the flame smoke inside will all correspond to the electric field. According to this principle, in the experiment base, the electric wand is used to push the flame away from the burner. “The flame is separated from the fuel, so it goes out.” The scientists now change the shape of the electrode in the wand, the current intensity, and frequency. , voltage, etc. to extend the fire extinguishing distance and the scope of the fire. “Cadmadiri said that we have only recently begun to study its possible timetable.” In the end, a similar device can be installed on the ceiling of a building or on a ship, just like the current sprinkler - or portable, and firefighters can carry it on their backs, Cadelmadi guessed. However, he added that electric wands cannot cover all diseases. This type of fire extinguishing tool may only be used indoors. Electric wands do not work for forest fires and other large-scale fires, he said. He explained that "the effect we see depends on the strength of the electric field,". "To build a large electric field in a large area is a challenge," he said. In addition to extinguishing the fire, electric wands may only meet the needs of small fires such as engines, furnaces, and torches.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.