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Refrigeration > Refers/EPA Midterm > Flashcards

Refers/EPA Midterm Flashcards

1
Q

The synthetic lubricant presently used with ternary blends containing HCFCs is:

A

Alkylbenzene

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2
Q

Which is NOT true of recycling and recovery equipment manufactured after November 15, 1993?

A

It must have an oil separator.

Oil separators are NOT required.

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3
Q

Charging liquid refrigerant into a refrigeration system under 29 inches Hg vacuum can cause:

A

System water to freeze

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4
Q

R-22 is an ______ refrigerant

A

HCFC

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5
Q

R-12 is a _____ refrigerant.

A

CFC

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6
Q

R-123 is a ___ ______ refrigerant under EPA regulations for recycling refrigerant.

A

Low pressure

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7
Q

When working with solvents, chemicals, or refrigerants, a technician should review the:

A

Material safety data sheets

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8
Q

Under what code group of ASHRAE Standard 34 does R-123 fall?

A

B1

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9
Q

When leak testing a low-pressure centrifugal with nitrogen, what is the maximum test pressure?

A

10 psig

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10
Q

What else is NOT true of refrigerant recycling and recovery equipment manufactured after November 15, 1993?

A

It must be able to handle more than one refrigerant.

Refrigerants should NEVER be mixed!

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11
Q

Identify the pressure corresponding to 32°F for R-123

A

20 inches Hg vacuum

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12
Q

Each chlorine atom in the stratosphere can destroy ______ ozone molecules

A

100,000

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13
Q

How do you determine when enough vapor has entered the refrigeration system before you charge refrigerant liquid?

A

Refrigerant saturation temperature increases to 36°F

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14
Q

Recovery equipment that relies upon the Compressor in the appliance and/or the pressure of the refrigerant in the appliance would be considered:

A

System-dependent

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15
Q

Excessive running of a purge system on a low-pressure chiller generally indicates what condition?

A

The system is leaking

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16
Q

It will be illegal to vent substitutes for CFCs and HCFCs after:

A

November 1995

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17
Q

The oils that will be employed with most of the HFC-134a refrigeration applications are:

A

Esters

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18
Q

Liquid charging of an R-12 refrigeration system with risk of freezing is begun with vapor from a vacuum level to a pressure of approximately:

A

33 psig

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19
Q

The system dependent (passive) recovery process:

A

Recovers refrigerant in a non-pressurized container

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20
Q

Leak testing a low-pressure refrigeration system with the nitrogen in excess of 10 psig could cause what to fail?

A

Rupture disc

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21
Q

R-11 at 14.7 psia will boil at approximately:

A

74.5°F

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22
Q

When a system trace gas becomes absolutely necessary, which of the available refrigerants should be used to identify a leak?

A

HCFC-22

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23
Q

High head pressure could be an indication of:

A

non-condensables collecting in the condenser

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24
Q

Frost build up on the suction side of the compressor can

indicate __________.

A

too little superheat in refrigerant vapor

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25
Q

Which condition(s) can cause excessive pressure
conditions on the high side of a self-contained (active)
recovery device?

A

when the recovery tank inlet valve has not been
opened, and …

when there is excessive air in the recovery tank

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26
Q

When using recovery and recycling equipment
manufactured BEFORE November 15, 1993, technicians
must evacuate an appliance containing 10 pounds of
CFC-500 to what level before disposing of the
appliance?

A

4 inches of Hg vacuum.

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27
Q

Recovery equipment used during maintenance, service or repair of small appliances must be certified by an EPA-
approved laboratory if manufactured after:

A

November 15, 1993.

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28
Q

EPA regulations include which of the following in the

definition of a “small appliance”?

A

products manufactured, charged and hermetically
sealed in a factory, AND

products having 5 pounds or less of refrigerant

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29
Q

What should be done to reduce refrigerant loss from a

purge unit on a CFC-11 chiller?

A

leak test and repair the chiller

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30
Q

A heater used on a recovery vessel aids in the faster

transfer of ______ from the chiller during recovery.

A

vapor

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31
Q

On a sealed system with an operating compressor that
has a completely restricted capillary tube, how many
access valves are needed to evacuate the refrigerant?

A

Only one access valve, on the high of the system.

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32
Q

Removal of the refrigerant charge from a system can be

conducted more quickly by:

A

packing the recovery vessel in ice.

33
Q

The state of the refrigerant entering the compressor of a

refrigeration system is:

A

low pressure vapor.

34
Q

Which compounds have the highest ozone depletion

potential (ODP) ?

A

CFCs

35
Q

A rupture disc on a recovery vessel for low pressure

refrigerants relieves at:

A

15 psig

36
Q

Where does refrigerant go after it leaves the purge unit of

a low pressure centrifugal system?

A

the evaporator

37
Q

All recovery devices manufactured before November 15,
1993 for use with small appliances must meet which of
the following requirements?

A

capable of recovering 80% of the refrigerant whether or not the compressor is operating or achieving a 4 inch vacuum under conditions of ARI 740

38
Q

To remove ice from sight glasses or viewing glasses use:

A

an alcohol spray

39
Q

EPA regulations require that all appliances containing
more than 50 pounds of refrigerant (except for
commercial and industrial process refrigeration) be
repaired when the leak rate exceeds ___ percent of the
charge per year.

A

15

40
Q

When using recovery or recycling equipment
manufactured BEFORE November 15, 1993, technicians
must evacuate low-pressure appliances to the following
level before making a major repair:

A

25 inches of Hg vacuum.

41
Q

What should be done before transferring refrigerant to an

empty cylinder?

A

The cylinder should be evacuated.

42
Q

EPA regulations require that leaking commercial and
industrial process refrigeration be repaired when the leak
rate exceeds ____ percent of the charge per year.

A

35

43
Q

You are changing out the compressor of a system containing 40 pounds R-502. Your recycling equipment was manufactured AFTER November 15, 1993. In addition to isolating the compressor as much as possible, which of the following procedures should you follow?

A

Evacuate the isolated section of the system to 10 inches of

vacuum and hold. lf system pressure does not rise, remove the compressor.

44
Q

What is the typical design burst pressure for a rupture
disk on a low pressure centrifugal air-conditioning
system?

A

15 psi

45
Q

When using recovery and recycling equipment
manufactured AFTER November 15, 1993, technicians
must evacuate low-pressure appliances to the following
level before disposing of the appliance:

A

25 mm of Hg absolute

46
Q

When recharging a refrigeration system with R-11. What vapor pressure is necessary in the shells before charging with liquid?

A

16.9” Hg vacuum

47
Q

Noncondensables in a refrigeration system result in:

A

higher discharge pressure

48
Q

A standard vacuum pump designed specifically for

evacuation and dehydration can:

A

never be used as a recovery device in combination with a pressurized container.

49
Q

A storage cylinder of recovered R-22 at normal room
temperature (about 75 degrees F), in the absence of
non-condensables, will be pressurized to:

A

130 psig (see chart)

50
Q

Which of the following leak detection methods is
considered to be the most effective for locating the
general area of a small leak?

A

electronic or ultrasonic tester

51
Q

After installing and opening a piercing access valve, if
the system pressure is _________ do not begin the
recovery procedure.

A

o psig

52
Q

Which of the following is not an approved technique of

system cleanup after a burnout?

A

flushing with liquid refrigerant to clean field tubing.

53
Q

Equipment manufactured after November 15,1993 which
is used to recover refrigerant from small appliances for
the purpose of disposal must meet what standard?

A

Recover 80% with an inoperative compressor, AND 90% with an operative compressor.

54
Q

System-dependent recovery equipment CANNOT be

used when:

A

the appliance contains over 15 pounds of refrigerant.

55
Q

CFCs will no longer be manufactured or imported into the U.S. after:

A

1995

56
Q

When you check system pressures to determine the
performance of a refrigeration system, it’s always a good
idea to:

A

use equipment such as hand valves or self-sealing hoses to minimize any release.

57
Q

Recycling or recovery equipment using hermetic
compressors has the potential to overheat when drawing
deep vacuums because:

A

the motor relies on the flow of refrigerant through the compressor for cooling.

58
Q

The state of the refrigerant leaving the receiver of a

refrigeration system is:

A

high pressure liquid

59
Q

The piping connection to the vacuum pump should be:

A

as short in length and as large in diameter as possible.

60
Q

When using recovery and recycling equipment
manufactured AFTER November 15, 1993, technicians
must evacuate an appliance component containing
MORE than 200 pounds of CFC-12 to the following level
before making a major repair:

A

15 inches of Hg vacuum

NOT 4 INCHES!! As with recovery equipment manufactured BEFORE November 15, 1993.

61
Q

When servicing a small appliance for leak repair:

A

it is not mandatory to repair the leak but do so whenever possible

62
Q

The smallest container in which refrigerants may be sold to Section 608 certified technicians is:

A

20 pounds

63
Q

To speed the recovery process and ensure that all refrigerant has been removed from a frost-free refrigerator:

A

turn on the defrost heater to vaporize any trapped liquid

64
Q

An oil sample should be taken for which of the following reasons?

A

the unit has had a compressor burnout

65
Q

At high temperatures (i.e. open flames, flowing metal surfaces, etc.) R-12 and R-22 can decompose to form:

A

phosgene gas

66
Q

A nitrogen tank should always be equipped with a:

A

regulator

67
Q

R-11 at 18.1 in Hg vacuum has a saturation temperature of:

A

32*F

68
Q

Air in a low pressure system is indicated by:

A

high head pressure

69
Q

On a centrifugal system, the purge unit takes its suction from the:

A

top of the condenser

70
Q

Where does refrigerant go after it leaves the purge unit of a low pressure centrifugal system?

A

the evaporator

71
Q

Under EPA’s regulations, which of the following methods can be used to pressurize an R-11 or R-123 system for the purpose of opening the system for a non-major repair?

A

warming the refrigerant

72
Q

R-123 at __ inches of Hg vacuum corresponds to 32*F

A

20 in

73
Q

A deep vacuum is usually measured in:

A

MICRONS

74
Q

Where would you place a leak detector probe to check gas leaks into the water box with water removed?

A

through a drain valve (refrigerant would settle at the bottom of the water box)

75
Q

Refrigerant is added to a centrifugal machine through the:

A

evaporator charging valve

76
Q

When removing oil from a low pressure system, the temperature should be 130*F because:

A

less refrigerant will be contained in the oil at the higher temperature

77
Q

When using recovery or recycling equipment
manufactured BEFORE November 15, 1993, technicians
must evacuate low-pressure appliances to what
level before making a major repair?

What about AFTER November 15, 1993?

A

25 inches of Hg vacuum BEFORE Nov 15, 1993.

25mm of Hg absolute AFTER Nov 15, 1993.

78
Q

With a low-pressure chiller, what must you do after recovering the liquid refrigerant?

A

recover the vapor refrigerant

79
Q

Before using a recovery unit to remove a charge, what steps should be taken?

A

-Check service valve positions
-Check recovery unit oil level
-Evacuate recovery unit/receiver
(All of the above)

Refrigeration (2 decks)

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