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HVAC > Type 2 > Flashcards

Type 2 Flashcards

1
Q

Which part of a belt-driven non-hermetic compressor is most likely to leak if the compressor has not been used for serval months?

a. Suction service valve.
b. Rotating shaft seal.
c. One or both of the king valves.
d. Head gasket on discharge side.

A

B: Rotating shaft seal

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2
Q

Which of the following is an indicator of a leak in a high-pressure system with a capillary tube?

a. High head pressure
b. Low water temperature
c. Excessive superheat
d. Frequent purging

A

C: Excessive superheat

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3
Q

When a new system has been assembled, the first thing to do is: _________.

a) evacuate the system
b) pressurize the system with an inert gas and leak check
c) pressurize the system with refrigerant to be used in the system
d) introduce an initial charge of refrigerant and start the compressor

A

b) pressurize the system with an inert gas and leak check

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4
Q 
50 pounds or more of R-123 is leaking. what leak rate does EPA requires that the equipment be repaired
A) 5%
B) 10%
C) 15%
D) 20%
A

B) 10%

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5
Q 
retail food and cold storage warehouse sectors
A) Commercial refrigeration
B) Industrial PRocess refrigeration
c) Comfort cooling
d) Ice making refrigeration
A

A) Commercial refrigeration

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6
Q 
where must you connect a hose in order to recover liquid refrigerant
A) The compressor suction valve
B) The compressor discharge valve
c) The liquid line
d) the condenser inlet
A

C) The liquid line

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7
Q 
Recovering refrigerant from a system in vapor phase will minimize loss of:
A) water
B) oil
C) refrigerant
D) non-condensable
A

B) oil

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8
Q

how can you speed up the removal of the refrigerant charge from a system

a) Using a smaller recovery vessel
b) Cooling the recovery cylinder to lower its pressure
c) Using a two-stage vacuum pump
d) Heating the recovery cylinder to raise its pressure

A

b) Cooling the recovery cylinder to lower its pressure

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9
Q

why could a Recycling or recovery equipment using hermetic compressors has the potential to overheat when drawing deep vacuum because:
A. It runs faster than other equipment
B. The motor relies on the flow of refrigerant through the compressor for cooling
C. It has a higher compression ratio than other equipment
D. The oils used in hermetic compressors at lower temperatures than the oils used in other equipment

A

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

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10
Q

why do Gauges set hoses used for field service work should have self-sealing connectors or hand valves in order to:
A. Minimize the chance of an explosion during refrigerant recovery
B. Prevent venting during recycling
C. Minimize refrigerant release when hoses are connected and disconnected
D. Prevent vapor lock during liquid transfer

A

C. Minimize refrigerant release when hoses are connected and disconnected

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11
Q

refrigerant has been recovered from an air conditioning system and held in a refillable cylinder, in order to replace the condenser coil

a) may be charged back into the system
b) May be sold as is to another equipment owner
c) must be reclaimed
d) must be destroyed

A

a) may be charged back into the system

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12
Q 
Refrigerant should be removed from the condenser outlet when:
A. The condenser is below the receiver
B. The condenser is on the roof
C. The compressor is inoperative
D. The evaporator has a small leak
A

A. The condenser is below the receiver

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13
Q

Which of the following statements about recycling and recovery equipment for stationary refrigeration is FALSE

a) it must be tested by an EPA-approved third party
b) Purchaseed of such equipments must be reported to EPA
c) it must be equippend with low-loss fitting
d) equipment designed to recover flammable refrigerant must meet specific UL safety standard

A

b) Purchaseed of such equipments must be reported to EPA

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14
Q

You are changing out the compressor of a system containing 40 pounds of R-404A. In addition to
isolating the compressor, which of the following procedures should you follow?
A. Simply remove the compressor and cap the ends.
B. Evacuate the isolated section of the system to atmospheric pressure, then remove the compressor.
C. Evacuate the isolated section of the system to 0 psig and if system pressure does not rise after a few
minutes, remove the compressor.
D. Evacuate the isolated section of the system to 5 inches of vacuum and when the system’s pressure
rises out of the vacuum, remove the compressor.

A

C. Evacuate the isolated section of the system to 0 psig and if system pressure does not rise after a few
minutes, remove the compressor.

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15
Q

When can appliance containing refrigerants be recovered to atmospheris pressure?

a) for major repair
b) the repair is followed by an evacuation
c) leaks in the applicance make recovery to the prescribed level unattainable
d) the appliance is being disposed of and recycled

A

c) leaks in the applicance make recovery to the prescribed level unattainable

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16
Q

when is it against epa regulations to use system-dependent recoverywhen is it against epa regulations to use system-dependent recovery

a) when the compressor of the appliance is operational
b) when the ambient temperature is over 105’F
c) when the appliance contains over 15 pounds of refrigerant
d) when the appliance is leaking

A

c) when the appliance contains over 15 pounds of refrigerant

17
Q

what area of the refrigeration system does oil foaming usually occur?

a) condenser
b) evaporator
c) compressor
d) expansion device

A

c) compressor

18
Q

what refrigerant, detector NOT required

a) R-134a
b) R-404a
c) R-410a
d) R717

A

d) R717

19
Q

when could a reciprocating compressor be damaged if energized?

a) when the discharge service valve is closed
b) when the suction service valve open
c) when the discharge service valve is open
d) when the demand for cooling is at a steady state

A

a) when the discharge service valve is closed

20
Q

pressure relief valves can only be installed

a) in series
b) in parallel
c) vertically
d) horizontally

A

b) in parallel

21
Q

what is the best use for testing with soap bubbles

a) to pinpoint refrigerant leaks
b) to find refrigerant leaks in coil fin area
c) to detect leaks in water tube condensers
d) to detect leaks if the condenser is excessively dirty

A

a) to pinpoint refrigerant leaks

22
Q

50 pounds or more of R-22 leaks, how many days to repair the leak and conduct the initial leak verification test

a) 1 day
b) 10 days
c) 30 days
d) 45 days

A

c) 30 days

23
Q

after refrigerant liquid has been recovered from the applicance, any remaining vapor is

a) purges to the atmosphere
b) isolated in the appliance
c) pumped into applicance receiver
d) removed by the recovery system

A

d) removed by the recovery system

24
Q

what step should be taken before using a recovery unit to remove a charge?

a) the refrigerant should be tested for acid
b) the recovery unit should be purged with nitrogen
c) the oil in the recovery unit should be changed and the recovery cylinder evacuated
d) service valve positions and recovery oil level should be checked, when applicable

A

d) service valve positions and recovery oil level should be checked, when applicable

25
Q

An operating unit that has a receiver/storage tank requires refrigerant system service. When servicing
the unit;
A. the compressor should be valved off.
B. liquid refrigerant should be recovered last.
C. refrigerant should be pumped down to and isolated in the receiver.
D. a gauge pressure of “Ol/psi should be achieved by venting.

A

C. refrigerant should be pumped down to and isolated in the receiver.

26
Q

The method to charge a system that has a normal charge of 80 pounds is to charge with: ________.

a) vapor through the suction line service valve
b) liquid through the discharge service valve
c) liquid through the suction service valve
d) liquid through the liquid-line service valve

A

d) liquid through the liquid-line service valve

27
Q

should be replaced if a system is opened for servicing

a) filter direr
b) thermostat
c) metering device
d) crankcase heater

A

a) filter direr

28
Q

50 pounds of R-22 leaks more than 125%

a) retrofit
b) recover
c) retire
d) submit a report to EPA describing efforts to identify leaks and repair the appliance

A

d) submit a report to EPA describing efforts to identify leaks and repair the appliance

29
Q

When recovery is first started, at what phase is the refrigerant removed to save recovery time?

a) recovery phase
b) recycle phase
c) liquid phase
d) vapor phase

A

c) liquid phase

30
Q

what should be done before transfering refrigerant to an empty cylinder?

a) the refrigerant should be chilled
b) the refrigerant should be mixed
c) the cylinder should be heated
d) the cylinder should be evacuated

A

d) the cylinder should be evacuated

31
Q

what is the component directly following the condenser in a refrigerant system using a thermal expansion valve

a) receiver
b) compressor
c) accumulator
d) evaporator

A

a) Receiver

32
Q

it is best practice to use dry nitrogen to break the vacuum when dehydrating by the triple evacuation method. However, it:

a) often contains moisture
b) requires a minimum of 10 psig
c) is toxic when released into the atmosphere
d) requires a pressure regulator

A

d) requires a pressure regulator

HVAC (4 decks)

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