Study the active vocabulary.

 

1. to attempt                                              – пытаться;

an attempt                                             – попытка

2. removal                                                    – изъятие, удаление, отвод

 

starvation                                               – удаление горючего материала из зоны

withdrawal                                             горения

3. to cause                                                  – заставлять, причинять

a cause                                                    – причина

4. to go out                                                  – затухать, гаснуть

5. smothering                                           – изоляция

6. to deprive                                              – лишать

 

7. to eliminate                                          – устранять, исключать

8. effort                                                            – усилие

9. a means (pl. means)                – средство

10. to rely on (upon)                        – полагаться на

11. to expose                                           – подвергать

 

12. cooling                                                  – охлаждение

13. damage                                               – потеря, ущерб

14. to surround                                      – окружать

15. spill                                                            – разлив

 

16. to wrap                                                  – обертывать, заворачивать

 

17. to dissipate                                      – рассеиваться, разгонять

 

18. to displace                                        – вытеснять, заменять, замещать

19. propagation                                     – распространение

 

20. to reduce                                            – уменьшать

21. blanket                                                  – теплоизоляционное покрытие

 

22. oxidizer                                                 – окислитель

 

23. to sustain                                           – поддерживать

 

24. to suspend                                       – исключать, временно отстранять

25. heat exchanger                          – теплообменник

 

26. to supply                                             – доставлять, поступать

a supply                                               – поступление

27. to prevent                                          – предотвращать

 

 

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TEXT A

 

Discuss the questions with your partner.

 

1. What are the components of the fire triangle (tetrahedron)?

 

2. What should be done in order to extinguish a fire?

3. What fire extinguishment methods do you know?

 

Read the text using a dictionary if necessary. Check your answers for Ex. 2.

 

FIRE EXTINGUISHMENT

 

As such factors as heat, fuel, oxygen, and chain reaction are necessary for fire, it follows that the withdrawal of any of them will cause the fire to go out. So the theory of fire extinguishment is based on removing any one or more of the four elements in the fire tetrahedron to suppress the fire. Before attempting to extinguish a fire, the fireman must decide which of the factors he will try to remove. Efforts directed at removing the fuel are sometimes called starvation; depriving the fire of oxygen is known as smothering or blanketing and reducing the temperature is known as cooling.

 

It is often possible to use more than one method at the same time, in fact most means of extinguishment do so, although they are classified under the method on which they principally rely.

 

Removal of Fuel. This method is applied by removing from theneighbourhood of the fire such combustible materials which can be removed. It is often possible to transfer stock or other contents from the parts of a burning building to a safe place. When dealing with flammable liquid fires, valves can be shut off and storage vessels pumped to safe areas to help eliminate the supply of fuel to the fire. Flammable gas fires are completely extinguished by shutting off the fuel supply. These and similar actions may be of great value in reducing the potential damage, but they do not generally provide positive action against fire. Moreover, under many circumstances, it is not practical to attempt to remove the fuel from the fire. Smothering or cooling is usually more useful.

 

Smothering or blanketing. This is an attempt to reduce the supply ofoxygen necessary for the fire. A reduction of the proportion of oxygen in the atmosphere from the normal 21% to less than 15% will extinguish most fires, but in some cases the percentage of oxygen must be reduces as low as 0%. When the burning material, e.g. celluloid, includes in its chemical composition sufficient oxygen for its combustion, smothering is, of course, ineffective.

 

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Examples of smothering include the use of sand to cover small fires of spilled oil and wrapping a blanket around a person whose clothing is burning. Inert gases or vapours may be used to displace the air surrounding a fire or to reduce the oxygen content of the atmosphere below the level required for combustion to continue. Such a “blanket” is, of course, a temporary one because the gases tend to be dissipated by the convection currents set up by the heat of the fire or in the open air by droughts. Carbon dioxide, carbon tetrachloride, methyl bromide and chlorobromomethane are the extinguishing agents usually used in this case.

 

Cooling. In order to remove the heat, something must be applied to thefire to absorb the heat or act as a heat exchanger. Water is not the only agent used to accomplish this, but it is the most common. This is possible through water’s ability to absorb massive amounts of heat by converting water to water vapor.

 

Interruption of Chain Reaction. Modern extinguishing agents, suchas dry chemical and halons, have proven to be effective on various fires even though these agents do not remove heat, fuel, or oxygen. Dry chemical and halogenated agents are thought to suspend “free radicals” that are created in the combustion process and thus prevent them from continuing the chain reaction.