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Chapter 7 compressors Questions and Answers

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Chapter 7 compressors Questions and Answers 1. What are the two primary functions of a refrigeration compressor? To lower the pressure and temperature in the evaporator, and raise the pressure and temperature on the condenser side of the system 2. Which type of compressor is most popular i...

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  • July 23, 2024
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  • 2023/2024
  • Exam (elaborations)
  • Questions & answers
  • Compressors
  • Compressors
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Chapter 7 compressors Questions and Answers
1. What are the two primary functions of a refrigeration compressor? - answer To lower the pressure and temperature in the evaporator, and raise the pressure and temperature on the condenser side of the system
2. Which type of compressor is most popular in commercial refrigeration? - answer Reciprocating
3. Describe the basic construction of a hermetic compressor? - answer Entire motor, and pump assembly sealed inside a welded canister with only access tubes, and electrical connections penetrating to steel housing
4. What is meant by volumetric efficiency? - answer The amount of refrigerant actually pumped in every stroke cycle of the piston compared to the actual value of the cylinder
5. What is heat of compression? - answer The amount of heat generated when the piston compresses the low pressure refrigerant vapor into a high-pressure vapor
6. What is the maximum allowable condensing temperature on a compressor? - answer 275°F
7.At what temperature will oil Carbonize on the head and valve plate on a compressor? - answer 350°F
8. How does maximum condensing temperature relate to oil carbonization? - answer At 275° condensing temperature, the temperature on the head of the compressor is about 350°, the carbonizing point of the oil
9. What does a suction valve on a compressor look like? - answer A thin piece of Shiny spring steel
10. What does a discharge valve on a compressor look like? - answer A thin piece of
shiny spring steel with a heavy steel backing plate mounted with high tension springs
11. How do you check the suction valves on a compressor? - answer Front seat the suction service valve and make sure the compressor pumps down to at least 15+ "HG
12. How do you check the discharge valves on a compressor? - answer Front seat the suction service valve and make sure the compressor pumps down to at least 15+ HG, then turn off the compressor, and front seat the discharge valve. If the pressure rises at all on your suction gauge, the discharge valve is leaking.
13. Most suction valve damage on compressors is due to what? - answer Liquid slugging the compressor
14. Most leaking discharge valves can be attribute it to what? - answer Carbon buildup from high condensing temperatures
15. How many BTU is a one horsepower compressor? - answer Depends on the compressor and evaporator temperature must use spec chart
16. What happened to the capacity of a compressor as they evaporator temperature decreases? - answer The suction pressure decreases therefore the compressed volume of refrigerant decreases, meaning less capacity
17. What type of oil lubrication system is used on compressors under five HP? - answer Splash system
18. What type of oil lubrication system is used on compressors over 5 HP? - answer Oil pump
19. What are the important traits of refrigeration oil? - answer Low pour point, low wax build up. Good insulating (dialectic) qualities, high temp carbon point
20. Why must oil be miscible with the refrigerant? - answer So that the refrigerator returns the oil to the compressor crankcase as it is pumped through the system
21. how are compressors cooled? - answer Suction vapor entering the compressor, and air over the compressor from the condenser fan
22. How do you check the condensing temperature? - answer Measure it at a point on the discharge line 6" out of the compressor
23. If you tear down the compressor and the piston rods are broken, what caused the problem? - answer Liquid slugging the compressor
24. If you read a resistance from the motor windings to ground, what caused the problem? - answer Acid buildup from moisture in the system
25. Copper plating on steel parts, like pistons and the crankshaft, indicate what? - answer Acid buildup in the system
26. If the discharge valve backing plates are severely deformed, what caused the problem? - answer Liquid slugging the compressor

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