Unit 5. Classification of fire extinguishers

Useful vocabulary

• cardboard –картон

• to involve – включать в себя

• flammable – воспламеняемый

• combustible – горючий

• a solvent – раствор/растворитель

• a medium – агент/посредник/среда/промежуточная ступень

• to be suitable for – подходить/соответствовать

• water mist – тонкораспыленная вода/водяной туман

• reignition – повторное воспламенение

• residue – остатки сгорания

• a nozzle – (распыливающий) наконечник

• to scatter – распылять/рассеивать

• to approve - одобрять

• harmful - вредный/пагубный

Task I. Read the text

The National Fire Protection Association classifies fires into five general categories (U.S.):

Class A fires are ordinary materials like burning paper, cardboard, plastics, etc. Class B fires involve flammable or combustible liquids such as gasoline, kerosene, and common organic solvents used in the laboratory. Class C fires involve energized electrical equipment. Water can be a dangerous extinguishing medium for class C fires because of the risk of electrical shock unless a specialized water mist extinguisher is used. Class D fires involve combustible metals. These materials are known to burn at high temperatures and they will react violently with water, air, and/or other chemicals. K fires are kitchen fires. Some fires may be a combination of these! Your fire extinguishers are considered to have ABC ratings on them.

Here are some typical extinguishers and their uses:

Water extinguishers are suitable for class A fires, but not for class B, C and D fires such as burning liquids, electrical fires or reactive metal fires. In these cases, the flames are expected to spread or the hazard will be made greater!

Dry chemical extinguishers are useful for either class ABC or class BC fires and are your best all around choice for common fire situations. They leave a blanket of non-flammable material on the extinguished material which reduces the likelihood of reignition. Note that there are two kinds of dry chemical extinguishers:

CO₂ (carbon dioxide) extinguishers are for class B and C fires. They don't work very well on class A fires because the material usually reignites. CO₂ extinguishers have an advantage over dry chemical in that they leave behind no harmful residue.

Water mist extinguishers are ideal for Class A fires. Unlike an ordinary water extinguisher, the misting nozzle provides safety from electric shock and reduces scattering of burning materials. This is one of the best choices for protection of hospital environments, books, documents.

Metal/Sand Extinguishers are for flammable metals (class D fires) and work by simply smothering the fire. The most common extinguishing agent in this class is sodium chloride, but there are a variety of other options. You should have an approved class D unit if you are working with flammable metals.

Task II. Say if the statements are

1. There are five general fire categories

a. true b. false c. no such information in the text

2. Sodium chloride is usually used smothering class D fires

a. true b. false c. no such information in the text

3. CO₂ extinguishers are less effective in comparison with dry chemical extinguishers

a. true b. false c. no such information in the text

Task II. Answer the following questions

1. How many classes of fire do you know?

2. What materials are involved in Class B fires?

3. Why water is dangerous in Class C fires?

4. What type of a fire extinguisher is the best one for common fire situations?

5. What are the functions of the misting nozzle of water mist extinguishers?

6. What do you know about metal/sand extinguishers?

Task III. Provide Russian/English equivalents for the given words and phrases

• ordinary materials, flammable liquids, a dangerous medium, an electrical shock, in this case, to be useful for, to reduce the likelihood, scattering of burning materials;

• гореть при высокой температуре, подходить для, опасность, распространяться, повторное возгорание, иметь преимущество, обеспечивать безопасность.

Task IV. Make up 2 sentences using words and phrases from Useful vocabulary and Task III. Ask your colleagues to translate them from English into Russian or vice versa on the spot

Task V. Combine the words in the right way to make correct sentences. Translate them

1. Combustible, react, water, air, and, other, metals, with, chemicals.

2. two, extinguishers, are, kinds, of, dry, There, chemical.

3. behind, don’t, CO_2, extinguishers, leave, any, residue, harmful.

4. sodium, The, D, common, most, agent, in, class, extinguishing, fires, is, chloride.

5. extinguisher, electrical, A, specialized, the, risk, mist, water, is, to, reduce, of, shock, used.

Task VI. Grammar focus. Revise the Complex Subject: find the examples in the text

Task VII. Translate the following sentences paying attention to the Complex Subject constructions

1. The fire was reported to have Class D.

2. The weather is expected to be extremely hot.

3. This door is a fire exit. You are not supposed to block it.

4. The company is said to start hiring new employees.

5. I am believed to get a bonus for my hard work.

6. The sun is known to be very old.

7. Fire extinguishers are considered to be a must at every public place.

8. The criminal is supposed to have escaped by climbing over the wall.

9. The Russian federation is known to have a vast territory.

10. He is said to be studying at the moment.

Task IX. Paraphrase the sentences using the Complex Subject constructions

1. The Internet is extremely popular nowadays.

2. He will get a promotion soon.

3. They have built a new trade centre recently.

4. The population of the Earth is rising very fast.

5. A strong wind blew down many trees yesterday.

6. He goes to the gym three times a week.

7. Vegetarians don’t eat meat.

8. We will finish the lesson in 30 minutes.

9. They have decided to arrange a party for welcoming new colleagues.

10. The company invests a lot of money into advertising.