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MIDTERM UNITS 1-8 > UNIT 3 > Flashcards

UNIT 3 Flashcards

1
Q

Kinetic displacement compressor used in large air conditioning systems.

A

Centrifugal

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2
Q

Absorbs heat into the system and changes liquid refrigerant to vapor.

A

Evaporator

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3
Q

Ultrasonic, electronic, halide, bubble solution or dye are devices used for this purpose.

A

Leak detection

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4
Q

Another name for the discharge line immediately exiting the compressor.

A

Hot gas line

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5
Q

To process refrigerant to new product specifications.

A

Refrigerant reclaim

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6
Q

Subcooled liquid goes through this device and changes from high temp/high pressure liquid to low temp/low pressure liquid.

A

Metering device

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7
Q

Positive displacement compressor that uses two nesting screws.

A

Screw

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8
Q

12,000 btu/hr.

A

Ton of refrigeration

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9
Q

Rejects heat from the system, changes high temp/high pressure vapor into high temp/high pressure liquid.

A

Condenser

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10
Q

Positive displacement compressor that converts circular motion into up and down motion to compress the refrigerant vapor using piston(s) in a cylinder(s).

A

Reciprocating

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11
Q

The line exiting the condenser is also known as this.

A

Liquid line

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12
Q

A substance that can be changed readily to a vapor by boiling and then changed back into a liquid by condensing it.

A

Refrigerant

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13
Q

The line running from the exit of the evaporator to the inlet of the compressor.

A

Suction line

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14
Q

A positive displacement compressor that uses a rotating drum like piston that squeezes refrigerant against a stationary drum like piston.

A

Rotary

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15
Q

To remove moisture from air.

A

Dehumidifying

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16
Q

True or false
The cylinder color for R - 12 is light blue.

A

False, it is white

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17
Q

True or false
R-410A is a HFC refrigerant.

A

True

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18
Q

True or false
R-290 has a safety classification of A3.

A

True

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19
Q

True or false
When a refrigerant is saturated, both liquid and vapor can exist simultaneously.

A

True

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20
Q

When a refrigerant containing chlorine is burned, what is produced?

A

Toxins/ fosgene gas

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21
Q

What is the cylinder color for R-420A?

A

Rose

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22
Q

Name two HFC refrigerants.

A

R-11 & R-12

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23
Q

Name two HFC refrigerants.

A

R11 & R12

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24
Q

Name one HC refrigerant

A

R 290

25
Q

What HFO refrigerant is being used in automobiles to replace R-134a?

A

R1234YF

26
Q

What is the process of refrigeration?

A

To remove unwanted heat from a substance and transferring that heat to a place where it makes little to no difference.

27
Q

If the condenser is a standard tube and fin setup, what is the estimated ambient temperature outside of the condenser?

A

90 F

28
Q

At what temperature is the liquid refrigerant entering the metering device?

A

100 F

29
Q

Low side pressure gauge reads 125 psig for a system using R-410A. Thermocouple at the exit of the evaporator reads 55 F. Calculate superheat.

A

55-43 = 12 F

30
Q

High side pressure gauge reads 124 psig for a system using R-134a. Thermocouple placed just before the metering device reads 95 F. Calculate system subcooling.

A

100 - 95 = 5 F

31
Q

R-407C at 85 F has a corresponding pressure of ____ psia.

A

112.3 psia

32
Q

R-1234yf at 1.67 C has a corresponding pressure of ____ psig

A

35.01 psig

33
Q

R-404A at -40 F has a corresponding pressure of ____ psia

A

19.8 psia

34
Q

R-22 at 100 F has a corresponding pressure of ____ psig.

A

195.9 psig

35
Q

R-410A at 37.78 C has a corresponding pressure of ____ psig.

A

317 psig

36
Q

R-134a at 25 psia has a corresponding temperature of ____ C.

A

-13.89 C

37
Q

R-22 at 358.9 psig has a corresponding temperature of ____ F.

A

145 F

38
Q

R-410A at 50.9 psig has a corresponding temperature of ____ F.

A

2 F

39
Q

R404A at 103 psia has a corresponding temperature of ___ C.

A

5 C

40
Q

You are going to use the recovery cylinder of R-134a to charge module #7 with 20 oz of refrigerant. How do you check the recovery cylinder to make sure there are no non-condensables in the cylinder?

A

Check PT chart, if more than temp/press relationship, there’s non-condensables

41
Q

The data plate on the outdoor condensing unit of a system using R-22 states the subcooling for the system should be 10degrees of subcooling. You hook up your gauges and thermocouples and the high side pressure gauge reads 196 psig. The thermocouple reads 95 F. Calculate subcooling.

A

Unit is undercharged

42
Q

High temperature refrigeration is produce by _____.

A

An air conditioning system

43
Q

Medium temperature systems typically maintain products at temperatures between ___ F and ____ F.

A

35 and 40

44
Q

The ____ and _____ are used to change the vapor to liquid and the liquid back into a vapor.

A

Condenser and evaporator

45
Q

High temperature refrigeration systems keep the space cooled from ____F to ____F.

A

68 to 80

46
Q

As pressure increases, the boiling point ____.

A

Increases

47
Q

What is the reason for insulating the suction line?

A
  • Insulation helps prevent direct outside heat from entering system through suction line.
  • Prevent condensation
  • Prevent excessive heat from entering system

Sublimation = skipping a phase state

Ex. Ice to vapor

48
Q

1600 ft3 of air at 80 F enters an air handler with an evaporator coil. The air temperature at the exit of the air handler is 60 F. What is the volume of air leaving the air handler?

A

1540^3ft

49
Q

40 ft3 of a gas is stored in a container at 100 F at a pressure of 40 psig. The container is connected to by pipe to one that will hold 60ft^3 for a total volume of 100 ft^3 and the gas temperature is lowered to 80 F. What is the pressure in the combined containers?

A

6 psig

50
Q

Low pressure refrigerants have a pressure of ____ psig or lower at a liquid phase temperature of 104 F.

A

30

51
Q

True or false
Ester based refrigerant oils are very hygroscopic and will absorb moisture out of the air and through some containers.

A

True

52
Q

An average 350 ton, R-123 chiller (Type III), at 0 psig, would still have approximately ___ pounds of refrigerant in the vapor state.

A

100

53
Q

Rupture disc on a recovery vessel for low pressure refrigerants relieves at ___ psig.

A

15

54
Q

What is the proper Department of Transportation (DOT) marking on a recovery cylinder that is rated for R-410A refrigerant?

 A. 4BA350
 B. 4BA400
 C. 4BW400
 D. B & C
A

D. B & C

55
Q

True or false
Any system designed to contain a flammable hydrocarbon (HC) or HFO refrigerant has to have a leak test before evacuating to 500 microns or lower.

A

True

56
Q

What can you do to help speed up recovery/dehydrating a system?

A

Heat it & Beat it

57
Q

True or false
A technician servicing an external electrical circuit or sections of the system that do not involve the refrigerant components does not have to be Section 608 certified.

A

True

58
Q

R-407C at 270.8 psig has a corresponding temperature of

A

155F

MIDTERM UNITS 1-8 (8 decks)

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