Memorize the terms in Fig. I
suction to compressor всасывание компрессора
L.P. liquid (low pressure liquid) жидкость при низком давлении
regulator регулирующий вентиль
superheat removal снятие перегрева
liquid cooling охлаждение жидкости (конденсата)
delivery valve нагнетательный, подающий клапан
suction valve всасывающий клапан
WORK IN CLASS
I. Translate the text.
II. Make up 5 sentences of your own using word combinations from Ex. 2 (Lab. Work).
III. a) Find in the text the passage describing the operation of the regulator.
b) Pick out the phrases containing the future tenses; analyze these forms and translate them.
IV. Write out from the text the words naming essential parts of the equipment described in this text.
V. Choose the right word in the list and complete the sentences. gauge, regulator, evaporator, compressor, receiver, condenser
Is it right to say that...
1. A device where the heat of compression is extracted is the ... . 2. A device where the gas is recompressed is the ... . 3. A device which acts as a storage vessel is the ... . 4, A device which passes liquid refrigerant only at the proper rate is the ... . 5. A device that cools the surrounding air is the ... . 6. A device that shows the pressure is the ... .
VI. Answer the following questions on the text.
One student asks questions, the other answers them with a short response.
M о d el. What is illustrated in Fig. 1? - A refrigerator circuit.
1. What do the evaporator coils consist of? 2. Where are the grids? 3. Where is the air cooling battery placed? 4. What may a vessel contain? 5. By what medium is the evaporator cooled first? 6. What device cools the surrounding air? 7. What process causes the refrigerant to evaporate? 8. When does the dry gas remain in the evaporator? 9. Under what conditions will the gas in the compressor contain some liquid? 10. Why does the compressor crankcase become frosted? 11. What will happen if the regulator is insufficiently open? 12. What is the function of the regulator? 13. Does the regulator preserve the right proportion of charge in the condenser and evaporator? 14. To what pressure is the gas recompressed in the compressor? 15. When does the gas pass into the condenser? 16. By means of what medium is the heat extracted in the condenser? 17. When is the gas again becoming a liquid? 18. Where is the relationship pressure/temperature shown? 19. How does a receiver act? 20. For what purpose does the liquid refrigerant pass back to the regulator?
VII. Say what you can about the cycle of operation in a refrigerating plant. Use Fig. 1 and the following plan:
1. The evaporator. Its construction and function.
2. The role of the regulator in the system.
3. Function of the compressor.
4. The heat and the condenser.
The installation, operation and maintenance of the compressor must be carried out by trained personnel who are familiar with the contents of this instruction book.
The compressor must only be used to compress air.
Unauthorised remodelling or modification of the compressor may result in a safety hazard, and are not permitted.
Before any form of work is commenced on the compressor the electrical power must be turned off at the starter panel and at the main switchboard, and the switch on the main switchboard must be marked with a notice indicating that repair work is in progress. The discharge valve of the compressor must be closed, and the pressure must be released in all pressurised parts of the compressor.
The safety valves for LP and HP air, the bursting disc in the water mantle and any other safety equipment must be inspected regularly. Damaged components should be replaced with new, original parts. Adjustment of the safety valves shall only be carried out by authorised personnel. The compressor must never be used if the safety equipment is defective.
ABOUT THE COMPRESSOR
The compressor described in this instruction book is constructed as a two cylinder, two stage single action water cooled compressor. The principles of its construction are illustrated in Figures 2.1 and 2.2.
Fig. 2.1 Construction principles
The compressor’s first stage is often referred to as the low pressure (LP) stage, and the second stage is called the high pressure (HP) stage. The circulation of air through the compressor is shown in Figure 2.2.
Fig. 2.2 Air circulation
Explanation of symbols:
BLP suction valve
CLP delivery valve
DLP safety valve
ELP cooler (intercooler)
FHP suction valve
GHP delivery valve
HHP cooler (aftercooler)
IHP safety valve
All bearings in the compressor are pressure lubricated by means of a gear pump connected directly to the end of the crankshaft.
Two replaceable pipe coolers are mounted in the compressor’s cylinder block, one of which cools the compressed air after first-stage compression, while the other cools it after second-stage compression.
The intake and discharge of the cooling water is arranged so that it circulates through the cylinder block and ensures effective cooling of the air and the compressor’s cylinder walls.
The compressor increases the pressure of air from atmospheric pressure to a specified pressure, up to a maximum of 35 bar.
The compressor is normally fitted with an electric motor or other source of motive power on a well-braced baseplate, with a flexible coupling between the compressor and the motor.
All compressors are test run before delivery from the factory, and all installations with motors will have been correctly aligned.
This compressor, which is used to produce pressurised air for compressed air tools and instruments as well as starting air, satisfies the requirements of the certification companies.
The compressor is fitted with safety valves after first-stage compression and second-stage compression.
These safety valves are pre-adjusted upon delivery of the compressor to suit the working pressure specified by the customer, ensuring that the pressure does not exceed the limit for which the compressor and compressed air system are dimensioned.
A bursting disc is mounted on the cylinder block cooling water mantle, which ruptures if the coolant chamber is subjected to abnormally high pressure. The bursting disc must only be replaced with original plates supplied by the compressor supplier.
Important: The safety valves, bursting disc and any other safety equipment must be inspected regularly.