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Пособие 2 ч. МТД (Истомина).doc
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        1. Translate from Russian into English using the vocabulary of the Unit.

  1. Если бы древесина вдруг исчезла, жизнь очень бы изменилась.

  2. Сырьем для пиломатериалов является бревно определенного качества и размера.

  3. Инженер по деревообработке должен знать, как использовать древесину с наилучшей выгодой.

  4. Ценные породы древесины очень тяжелые и поэтому не используются для корпусов изделий.

  5. Лицевые поверхности покрываются шпоном из ценных пород.

  6. Сосна наиболее подходит для производства мебели, т.к. она легкая, дешевая и доступная.

  7. Орех, обладающий привлекательной текстурой, используется для декоративных целей как шпон.

  8. Лес необходимо заготавливать и восстанавливать одновременно.

  9. Существует много факторов, которые влияют на качество роста древесных растений и их конечную ценность.

  10. Чем севернее растет хвойное дерево, тем лучшую древесину оно дает.

  11. Лиственная древесина одной и той же породы значительно различается из-за природных условий.

V. Speak about:

1. Traditional classification of wood.

2. Utilization of different species.

Unit 4

Ing-forms.

Grammar:

Fireproofing

  1. Answer the questions:

  1. Does wood burn?

  2. Is it an advantage or disadvantage of wood?

  3. Is it possible to prevent wood from fire?

  1. Read the text and try to understand it.

To prevent wood from fire some chemicals or paints are usually used.

They are effective due to their preventing combustion of the charcoal. It should be taken into account that they can’t prevent chemical decomposition of the wood but they change the form in which this decomposition takes place. They may be called, therefore, fire retardant substances. Being treated with these substances wood becomes more fire-resistant and durable.

There exist three groups of fireproof substances. The first group of chemicals melts at a temperature below that at which wood decomposes. These chemicals form a glaze preventing access of oxygen to the wood. The second group of chemicals decomposes under heat, yielding non-inflammable gases. These gases dilute the inflammable gases of the decomposing wood and form a non-inflammable mixture.

The third group of chemicals evaporates at relatively low temperatures. Therefore, chemicals of the third group absorb sufficient quantity of heat, preventing the temperature of the wood from rising to the critical decomposition point. The remaining heat is not enough to start the chemical decomposition of the wood.

Several chemicals are known to possess the properties of fireproofing. But because of their toxicity, hygroscopicity and cost being very high, the number of fire retardant chemicals is not very great. Only two or three of them are being in wide use nowadays.

Sometimes fire retardant paints are used instead of fire retardant chemicals. They function as an insulating and reflecting layer. They do not prevent the chemical decomposition of wood under heating.

Fire retardant paints have a limited practical application: they offer practically no protection in the event of an intense fire, they are not durable and cannot be applied to timber already painted with an oil paint.

General understanding

Answer the questions:

    1. Is there any possibility to prevent wood from fire?

    2. How can we make wood more fire-resistant and durable?

    3. What is the function of the fireproof substances?

    4. Are there any chemicals possessing the properties of fireproofing?

    5. What factors must we take into account when choosing the fire retardant chemicals?

    6. What is the function of fire retardant paints?

    7. Can fire retardant paints prevent the chemical decomposition of wood under heating?

    8. Have the fire retardant paints a wide practical application?

    9. Do fire retardant paints offer considerable protection in the event of an intense fire?

    10. Are fire retardant paints applied to timbers already painted with an oil paint?