2020-05-12
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1. Древние люди верили, что огонь – э т о священная субстанция, которая придает силы.
2. На самом деле огонь – это химическая реакция, при которой могут выделяться свет, тепло и дым.
3. Существуют три стадии развития пожара: начальная стадия (или тление), стадия открытого пламени и полный охват помещения огнем.
4. Для того чтобы предотвратить пожар, необходимо хорошо понимать процесс горения.
5. Стадия полного охвата помещения пламенем наступает, когда воспламеняются все предметы в этом помещении.
6. Основными элементами пожарного треугольника являются тепло, горючее вещество и вещество, способствующее горению.
7. В обычных условиях веществом, поддерживающим горение, является кислород, также им могут быть и другие газы, например, хлор или бром.
8. Цепная реакция не дает горению прекратиться до тех пор, пока, по крайней мере, один из элементов пожарного треугольника не будет исключен.
9. Традиционные методы пожаротушения состоят в исключении одного из элементов пожарного треугольника.
10. Цепная реакция является четвертым фактором, необходимым для возникновения пожара, таким образом, мы можем говорить о пожарном четырехугольнике.
Express the main idea of the text in 5–7 sentences. Write your summary.
Retell the text according to the following plan.
1. Combustion.
2. Stages of a fire.
3. Fire triangle (tetrahedron): – heat;
– fuel;
– oxygen;
– chain reaction.
Be ready to work on the following projects.
1. Area of Fire.
2. Stages of Fires.
3. How Does the Fire Spread (Convection, Conduction and Radiation).
4. Flashovers and Backdraft.
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TEXT B
Read the text.
PROTECT YOUR HOME
The best way to protect your structure from being damaged by a wildland fire is to prevent it from starting on fire in the first place. To do this, one must know of the many ways fire spreads from one fuel source to another.
One way a structure starts on fire is through radiation. Heat travels via electromagnetic waves, without objects or gases carrying it along. Radiated heat goes out in all directions, unnoticed until it strikes an object. Burning buildings can radiate heat to surrounding structures, sometimes even passing through glass windows and igniting objects inside. The amount of heat produced depends on:
– the size of the flame: generally, larger flames release more heat;
– the amount of surface area on the structure exposed to the radiant heat: the larger the piece of surface that is exposed, the greater the chance of ignition;
– duration of exposure: the more time the structure is exposed the greater the likelihood of ignition;
– the distance between the flames and the structure: the closer the flames are to the structure, the greater the chance of ignition.
A second way a structure may start on fire is through conduction. Conduction is caused by direct contact between the flame and the structure. Firebrands, which are small pieces of burning material often carried by wind, can start new fires, and are a common form of conduction. Minimizing the chance of loss due to firebrand-started ignitions include:
– using non-flammable building materials in the construction of your home. This is especially important when considering the type of roof to install;
– planting appropriate vegetation around structures.
Convection is a third way fire spreads. Convection is caused by the superheated air that rises from the fires and pre-heats the fuels above it. Convection is most often associated with steep slopes and the "Chimney Effect". The best way to minimize loss due to convective heating include:
– build all structures back away from steep slopes. The edge of these steep slopes often provides the best view but can also make the home extremely difficult to protect during a wildland fire;
– avoid building your home at the top of steep canyons.
If a structure is properly insulated from all these types of spreading, the chances of the structure being lost or damaged to a wildfire will be minimized.
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Choose the correct answer for the following statements.
1. The text is addressed to…
A) house owners.
B) firefighters.
C) fire inspectors.
D) architects.
2. The purpose of the author is to inform …
A) about the ways the fire spreads from one place to another.
B) how to prevent fires from starting.
C) how fires usually start.
D) what to do when the fire occurs.
3. Wildland fire starts…
A) inside the house.
B) outside the house.
C) in the roof.
D) in the fireplace.
4. The word “to insulate” means …
A) “to expose”.
B) “to build”.
C) “to separate”.
D) “to isolate”.
5. Which of the following statements is false?
A) The larger the flame the more heat is emitted.
B) The larger the surface area exposed to the heat the greater the chances of ignition.
C) The more the distance between the flame and the structure the greater the chance of ignition.
D) The longer the structure is exposed to the flame the greater the chances of ignition.
6. The word “likelihood” means …
A) “chance”.
B) “exposure”.
C) “time”.
D) “duration”.
7. The passage of heat energy through or within a material because of direct contact is called…
A) radiation.
B) convection.
C) conduction.
D) combustion.
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8. The flow of fluid or gas from hot areas to cooler ones is called…
A) radiation.
B) convection.
C) conduction.
D) combustion.
9. People do not notice heat until it strikes an object in case of…
A) radiation.
B) convection.
C) conduction.
D) combustion.
10. “Chimney effect” in this text refers to…
A) a fire started in the chimney.
B) a brick or stone structure that is built over a fireplace.
C) a house built on the top of a steep canyon.
D) a column of hot gas and smoke that rises high into the air from the fire.
TEXT C
Translate the following text in writing.
FLASHOVER
A flashover is the near-simultaneous ignition of most of the directly exposed combustible material in an enclosed area. When certain organic materials are heated they undergo thermal decomposition and give off flammable gases. Flashover occurs when the majority of the exposed surfaces in a space are heated to their ignition temperature and emit flammable gases. Flashover normally occurs at 500 °C (930 °F) or 1,100 °F for ordinary combustibles.
An example of flashover is when a piece of furniture is ignited in a room. The fire involving the initial piece of furniture can produce a layer of hot smoke which spreads across the ceiling in the room. The hot buoyant smoke layer grows in depth, as it is bounded by the walls of the room. The radiated heat from this layer heats the surfaces of the directly exposed combustible materials in the room, causing them to give off flammable gases. When the temperature of the evolved gases becomes high enough, these gases will ignite, throughout their extent.
Flashover is one of the most feared phenomena among firefighters. Firefighters are taught to recognize flashovers and avoid backdrafts. For example, they have certain routines for opening a closed door in a building on fire, such as positioning adjacent to the door instead of in front of it. A firefighter has about 2 seconds to evacuate a flashover environment, even if wearing proper gear.
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LISTENING
21. You are going to watch a video. Before watching discuss the questions with your partner:
1. What is flashover?
2. What should you do in case of a fire at home?
3. What devices help to detect and put out fires in buildings?
Watch the video “FLASHOVER: THE POWER OF FIRE” at http://www.youtube.com/watch?v=GPweBlXNfxo
