Part 2. Oil pressing machines.

Exercise 1. Translate the following words and word-combinations without a dictionary. Hydraulic press, stationary, pressing operation, practical operation, material, optimum, ideal.

Reading. Read the text and explain advantages of using hydraulic and screw presses in oil industry.

Many different mechanical devices have been used for pressing. The Romans developed a screw press, described by Pliny, for the production of olive oil. Centuries ago, the Chinese employed the same series of operations followed in modern pressing mills – namely, bruising or grinding the seeds in stone mills,

heating the meal in open pans, and then pressing out the oil in a wedge press. The Dutch, or stamper, press invented in the 17th century was used almost exclusively in Europe for pressing oilseeds until the early part of the 19th century, when the hydraulic press was developed.

Hydraulic press is a device consisting of a cylinder fitted with a sliding piston that exerts force upon a confined liquid, which, in turn, produces a compressive force upon a stationary anvil or base plate. The liquid is forced into the cylinder by a pump. The hydraulic press manufactured in a wide variety of styles and sizes and in capacities ranging from 1 ton or less to 10,000 tons or more. The yield of oil from the hydraulic press was considerably higher than that from earlier processing methods because of the much higher applied pressures. In open presses, the ground seed material was confined in cloths of human hair or, less commonly, camel hair. Pressures on the cake varied from approximately 70 to 140 kilograms per square centimetre (1,000 to 2,000 pounds per square inch), and in the closed-type press, in which the oil-containing material was confined in a strong perforated steel cage during the pressing operation, pressures of approximately 400 kilograms per square centimetre or more were attained. Under ideal conditions the oil content of the hydraulic-press cake can be reduced to about 3 percent, but in practical operation a 5 percent level is average.

Figure 59. Screw press.

The modern screw press replaced many of the hydraulic presses because it is a continuous process, has greater capacity, requires less labour, and will generally remove more oil. As ground seed is fed continuously into the mechanical press, a worm screw increases the pressure progressively as the material moves through a slotted barrel. Pressures from 700 to 2,100 kilograms per square centimetre are attained, and the oil is squeezed out through the slots, leaving a cake containing 3 to 3.5 percent oil under optimum processing and 4 to 5 percent oil under average conditions.

Exercise 2. Translate the following word-combinations.

A cylinder fitted with a sliding piston, upon a stationary anvil, grinding the seeds in stone mills, the ground seed material, in a strong perforated steel cage, to be forced into the cylinder by a pump, a confined liquid, the closed-type press, through a slotted barrel, a worm screw.

Exercise 3. Checking facts and ideas. Decide if these statements are true or false.

1. The modern screw presses have greater capacity and require more labour than other types of presses. 2. Cold-drawn oils contain the least amounts of impurities because of preliminary cooling.

3. The hydraulic press productivity is higher of the stamper one because of higher applied pressures. 4. The screw press was developed by the Chinese.

5. The oil content of the hydraulic-press cake is 10 percent.

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Exercise 4. Complete each sentence with a word or phrase from the box.

modern screw press open presses screw press Dutch press magnetic separators

1. The hydraulic presses may be divided into closed-type and _____. 2. A _____ was developed by the Romans for the olive oil production.

3. The _____ requires less labour and has greater capacity than the hydraulic press. 4. To remove any stray of bits of metal the oil-bearing seeds are passed over ____. 5. The stamper is the second name of the _____.

Exercise 5. Choose a word or word-combination which is not a part of the logical group. Give a title for each words group.

a) cold-drawn, cold-pressed, coloured, virgin;

b) screw press, wedge press, stamper, filter, hydraulic press; c) worm screw, slotted barrel, steel cage, roll;

d) piston, anvil, cylinder, pump, die;

e) soybean, corn, sunflower, flax, cabbage, olive.

Exercise 6. Match the verbs with their meanings.

1) to bruise 2) to invent 3) to confine 4) to convert 5) to pass

6) to liberate

7) to manufacture 8) to concentrate 9) to squeeze

a) to originate (a method, a device)

b) to increase the strength of a liquid by removing water c) to reduce in size or alter in shape by extruding

d) make bigger, fuller, more elaborate e) to change in form or function

f) to keep or restrict within certain limits

g) to be transferred from one place to another h) to set free

i) to make articles on an industrial shape

10)to develop j) to crush

Exercise 7. Translate in the written form.

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