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3B2 > Ch. 11 > Flashcards

Ch. 11 Flashcards

1
Q
  1. When the pressure difference across a capillary tube is increased ___________________.

a. the flow of refrigerant increases
b. the flow of refrigerant decreases
c. the pressure of the refrigerant increases
d. the pressure of the refrigerant decreases
e. there is no change in the flow rate

A

a. the flow of refrigerant increases

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2
Q
  1. The king valve on an ammonia vapor compression system serves as a ______________________.

a. refrigerant control valve
b. valve to connect the ammonia drum when charging the system
c. brine control valve
d. master isolation shut-off valve
e. the condenser flow control

A

d. master isolation shut-off valve

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3
Q
  1. The automatic expansion valve is controlled by _____________.

a. transmitter
b. evaporator pressure
c. capillary action
d. refrigerant level
e. the king valve

A

b. evaporator pressure

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4
Q
  1. The thermostatic expansion valve controls refrigerant flow by __________________________.

a. liquid level in the condenser
b. a temperature sensor at the evaporator inlet
c. evaporator pressure
d. liquid level in the evaporator
e. a temperature sensor at the evaporator outlet

A

e. a temperature sensor at the evaporator outlet

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5
Q
  1. The low-side float valve is controlled by ______________.

a. refrigerant level in the receiver
b. the brine level
c. a float connected to/or in the evaporator
d. evaporator pressure
e. refrigerant level in the condenser

A

b. the brine level

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6
Q
  1. A capillary tube is mainly used on __________________.

a. large industrial refrigeration units
b. small household systems
c. ammonia systems
d. lithium bromide units
e. absorption systems

A

b. small household systems

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7
Q
  1. The high-side float is usually installed on ____________.

a. the liquid receiver or may act as a float chamber itself
b. the evaporator inlet
c. the condenser
d. the line between the compressor and condenser
e. the line between the condenser and receiver

A

a. the liquid receiver or may act as a float chamber itself

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8
Q
  1. The capillary tube has a __________________________.

a. very small diameter
b. medium sized diameter
c. large diameter
d. convergent-divergent cross-section
e. concaved cross-sectional area

A

a. very small diameter

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9
Q
  1. Refrigeration control can be achieved by regulating the flow of refrigerant to the evaporator and also by ______________.

a. increasing the brine concentration
b. regulating the output of the compressor
c. removing refrigerant from the system
d. increasing the level of the receiver
e. regulating the level of the condenser

A

b. regulating the output of the compressor

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10
Q
  1. The starting and stopping of the compressor is normally done automatically by means of __________________.

a. a pressure limiting device
b. an automatic low pressure cut-out
c. either a temperature actuated control or a pressure actuated control
d. a rheostat
e. a heat sensor in the evaporator

A

c. either a temperature actuated control or a pressure actuated control

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11
Q
  1. Condenser cooling water is usually controlled by ______________.

a. level controls
b. cooling tower demands
c. solenoid valves
d. hand operated gate valves
e. the level in the receiver

A

d. hand operated gate valves

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12
Q
  1. A low-pressure control in a refrigerating system can be used for _________________.

a. condenser pressure control
b. to start and stop the compressor
c. purging non-condensable gases
d. keeping the receiver pressure from getting too high
e. evaporator pressure control

A

b. to start and stop the compressor

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13
Q
  1. Low-pressure cut-outs are used on refrigeration systems to _________________.

a. stop the compressor on high pressure
b. stop the compressor when the suction pressure drops too low
c. shut the system down due to non-condensable gases
d. stop the compressor when charging the system
e. stop the compressor when the discharge pressure is too low

A

b. stop the compressor when the suction pressure drops too low

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14
Q
  1. Pressure relief devices may be _____________________.

a. safety valves and pressure limiting devices
b. low pressure cut outs and rupture members
c. relief valves, fusible plugs or rupture members
d. charging safety equipment
e. high & low level cut offs

A

c. relief valves, fusible plugs or rupture members

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15
Q
  1. An oil pressure failure switch is used to ______________.

a. prevent damage to the compressor due to inadequate lubrication
b. add oil automatically to the compressor
c. warn the operator of low oil
d. close the expansion valve if the oil pressure gets low
e. prevent damage to the condenser due to inadequate oil level

A

a. prevent damage to the compressor due to inadequate lubrication

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16
Q
  1. The oil separator is always inserted in the system __________________.

a. to prevent oil logging
b. in a cool pot
c. discharge line
d. suction line
e. the bottom of the evaporator

A

c. discharge line

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17
Q
  1. Oil separators and traps on an ammonia system _________________.

a. return the oil to the receiver
b. remove the oil from the condenser discharge and direct it to the drain
c. separate the oil from the compressor discharge and return it to the compressor
d. help the oil in the condenser and receiver to be drained when necessary
e. separate the oil from the receiver and return it to the compressor

A

c. separate the oil from the compressor discharge and return it to the compressor

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18
Q
  1. Purging lines and valves are usually located in ammonia compression systems on the _____________________.

a. evaporator outlet
b. bottom of the receiver
c. top of the receiver
d. compressor outlet
e. top of the evaporator

A

c. top of the receiver

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19
Q
  1. Refrigeration systems are purged ___________________.

a. to release excess refrigerant
b. to rid the system of non-condensable gases
c. to rid the system of moisture
d. to lower the evaporator pressure
e. to lower the system pressure

A

b. to rid the system of non-condensable gases

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20
Q
  1. Purge valves are required on a refrigeration system for ______________________.

a. ridding the system of oil vapors
b. getting rid of non-condensable gases in the brine
c. reducing back pressure on start-up
d. purging non-condensable gases out of the system
e. purging oil out of the condenser

A

d. purging non-condensable gases out of the system

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21
Q
  1. Moisture in refrigerating systems could cause _________________.

a. high temperatures
b. freeze-ups and clogged expansion valves
c. the relief valves to open
d. high discharge pressure
e. high suction pressure

A

b. freeze-ups and clogged expansion valves

22
Q
  1. The effects of moisture in a refrigeration system are __________________.

a. it helps to cool and increases the refrigeration effect
b. it does not cause any troubles
c. it can freeze and clog expansion valves
d. it prevents condensate from forming
e. it can cause high receiver level

A

c. it can freeze and clog expansion valves

23
Q
  1. Moisture in refrigeration systems can be removed by _______________.

a. purging
b. heating the refrigerant
c. making the oil more absorbent
d. using a dehydration device or strainer drier
e. blowing down the system

A

d. using a dehydration device or strainer drier

24
Q
  1. Freon leaks are usually detected by _________________.

a. a lighted sulphur stick
b. a sniffer
c. using a blow torch
d. a halide torch
e. a carbon tetrachloride detector

A

d. a halide torch

25
Q
  1. If dry nitrogen is used as a testing medium in refrigeration systems the following procedure should be used ________________.

a. remove the relief valves but not the controls
b. use higher pressure gauges
c. remove controls, relief valves and isolate the compressor and block off holes where relief valves were fitted
d. call the Boiler Inspector
e. all gas detectors must be activated

A

c. remove controls, relief valves and isolate the compressor and block off holes where relief valves were fitted

26
Q
  1. Before charging a refrigeration system, a high vacuum is maintained inorder to ______________________.

a. draw in atmospheric air
b. prevent an explosion
c. condense moisture to be removed
d. prevent condensate from evaporating
e. evaporate moisture so it can be removed in vapor form

A

e. evaporate moisture so it can be removed in vapor form

27
Q
  1. The liquid charging valve is usually connected to a line located _____________________.

a. between the liquid shut-off valve and the expansion valve
b. between the king valve and the condenser
c. at the compressor discharge line
d. between the purge valve and condenser
e. between the purge valve and the expansion valve

A

a. between the liquid shut-off valve and the expansion valve

28
Q
  1. In an indirect ammonia system using brine and a water-cooled condenser, the discharge pressure is controlled by ______________________.

a. the load on the brine
b. regulating the expansion valve
c. regulating the cooling water to the condenser
d. using a pressure release valve
e. the amount of ammonia refrigerant used

A

c. regulating the cooling water to the condenser

29
Q
  1. In an indirect ammonia vapor compression system using brine, the suction pressure is controlled by ________________.

a. the load on the brine
b. the flow of the condensing water to the condenser
c. throttling the metering valve
d. equalizing valve
e. the flow of the cooling water to the suction side of the compressor

A

a. the load on the brine

30
Q
  1. A pressure-limiting device will _____________________.

a. prevent the rupture disc from breaking
b. prevent the emergency disc from breaking
c. stop the compressor before the relief valves lift
d. keep the clearance pocket pressure regulated
e. prevent the pressure relief valve from discharging

A

c. stop the compressor before the relief valves lift

31
Q
  1. The emergency discharge line on refrigeration systems shall _______________________.

a. be connected directly to the top of the receiver or other vessel used for storing the refrigerant
b. be connected to the compressor
c. have two valves connected to charging drum
d. have two return bends in the piping
e. be connected directly to the top of the condenser and the compressor

A

a. be connected directly to the top of the receiver or other vessel used for storing the refrigerant

32
Q
  1. The emergency valve shall be installed _________________.

a. within reach of the receiver
b. outside of the engine room at a height of two metres
c. in a glass fronted box painted yellow
d. in a glass fronted box painted bright orange, inside of the control room and so placed that it cannot be tampered with by any other than the person called upon to open the valve in an emergency
e. in a glass fronted box painted bright red, outside of the building and so placed that it cannot be tampered with by any other than the person called upon to open the valve in an emergency

A

e. in a glass fronted box painted bright red, outside of the building and so placed that it cannot be tampered with by any other than the person called upon to open the valve in an emergency

33
Q
  1. The emergency line of refrigeration system shall be provided with a _____________________________.

a. check valve
b. diffuser at its upper end which shall be placed above the roof
c. strainer
d. drain valve
e. two stop valves

A

b. diffuser at its upper end which shall be placed above the roof

34
Q
  1. Pressure limiting devices of refrigeration systems shall be connected _________________________.

a. between the compressor and the stop valve on the suction side
b. to a blowdown tank
c. to the receiver outlet
d. between the compressor and the stop valve on the discharge side
e. between the inlet of the condenser and the outlet of the receiver

A

d. between the compressor and the stop valve on the discharge side

35
Q
  1. The person in charge of a refrigerating system, containing more than 23 kg of refrigerant _____________.

a. shall post a card of instructions near the refrigerant compressor
b. shall have the operating instructions in safe keeping
c. shall not worry about emergency instructions
d. shall give the operators the instructions
e. shall be operated by 3rd class power engineer only

A

a. shall post a card of instructions near the refrigerant compressor

36
Q
  1. Regulations for refrigeration are contained in the _________________.

a. CSA B-51 code
b. CSA B-52 code
c. ASME Section IV
d. ASME Section VII
e. ASME Mechanical refrigeration code

A

b. CSA B-52 code

37
Q
  1. The emergency valve on ammonia systems should be _____________.

a. located near the compressor
b. between emergency line and the evaporator
c. located outside the building
d. near the fire alarm
e. located at the exit leading to the outside of the building

A

c. located outside the building

38
Q
  1. High pressure cut-outs are used on refrigeration systems to ________________________.

a. stop the compressor when the pressure on the high pressure side of the system is too high
b. stop the compressor when the pressure on the low pressure side of the system is too low
c. stop the compressor due to non condensable gases in the system being too high
d. stop the compressor when changing the system
e. stop the compressor when the system ran too long

A

a. stop the compressor when the pressure on the high pressure side of the system is too high

39
Q
  1. Pressure limiting devices should be provided on a refrigeration system with more than ____ kg of refrigerant.

a. 1
b. 3
c. 5
d. 7
e. 9

A

e. 9

40
Q
  1. The problem with oil is the greatest in the ____________ of a refrigeration system.

a. condenser
b. receiver
c. evaporator
d. compressor
e. purger

A

c. evaporator

41
Q
  1. An oil separator is installed in refrigeration systems to prevent oil from carrying over to the ______________.

a. condenser
b. receiver
c. evaporator
d. compressor
e. purger

A

a. condenser

42
Q
  1. Which of the following oil separator used in a refrigeration consists of a series of baffles through which the oil laden refrigerant must pass?

a. Cyclone
b. Impingement
c. Oil still
d. Inverted trap
e. I.G.F.

A

b. Impingement

43
Q
  1. The presence of non condensable gases in a refrigeration system can cause _____________________.

a. breakdown of the lubricating oil
b. impurities in the refrigerant
c. low discharge pressure
d. high discharge pressure
e. low suction pressure

A

d. high discharge pressure

44
Q
  1. The majority of the non condensable gases in a refrigeration system tends to collect at the highest point of the _____________ naturally.

a. compressor
b. receiver
c. condenser
d. evaporator
e. purger

A

c. condenser

45
Q
  1. When moisture combines with refrigerants it could cause the formation of ______________________.

a. concentrated refrigerant
b. diluted refrigerant
c. mildly corrosive compounds
d. highly corrosive compounds
e. strong base cation

A

d. highly corrosive compounds

46
Q
  1. When using __________ as a refrigerant, moisture corrosion will not usually be a problem:

a. ammonia
b. propane
c. R-12
d. R-22
e. CO2

A

d. R-22

47
Q
  1. Before admitting any refrigerant, the entire refrigeration system is put _________________________________________________.

a. slightly above atmospheric pressure
b. well above atmospheric pressure
c. under a slight vacuum
d. under a high vacuum
e. above the dew point

A

d. under a high vacuum

48
Q
  1. A salometer is a type of _____________________ that is used to indicate the percentage of salt in a solution.

a. hydrometer
b. manometer
c. flowmeter
d. concentrator
e. spectrophotometer

A

a. hydrometer

49
Q
  1. When a concentrated solution is at its lowest freezing point, it is called a ______________________ solution.

a. sub temperature
b. super critical
c. sub critical
d. critical
e. eutectic

A

e. eutectic

50
Q
  1. The lowest freezing point obtainable for a mixture of sodium chloride and water is _____________.

a. -12°C
b. -21°C
c. -30°C
d. -43°C
e. -51°C

A

b. -21°C

51
Q
  1. The lowest freezing point obtainable for a mixture of calcium chloride and water is ___________.

a. -12°C
b. -21°C
c. -30°C
d. -43°C
e. -51°C

A

e. -51°C

3B2 (15 decks)

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