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Term 3 - Review Tests > 4th Year IP Exam #1 > Flashcards

4th Year IP Exam #1 Flashcards

1
Q

A cubic foot of water weighs

a) 8.33lb
b) 10lb
c) 62.4lb
d) 64.2lb

A

c)

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2
Q

A US gallon of water weighs

a) 8.33lb
b) 10lb
c) 62.4lb
d) 64.2lb

A

a)

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3
Q

An imperial gallon of water weighs

a) 8.33lb
b) 10lb
c) 62.4lb
d) 64.2lb

A

b)

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4
Q

The specific heat of water is

a) 1
b) 8.33
c) 10
d) 62.4

A

a

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5
Q

Latent heat of fusion of water (ice) is ___btu/lb

a) 5
b) 1
c) 144
d) 970

A

C

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6
Q

Latent heat of vaporization of water (steam) is ___btu/lb

a) .5
b) 1
c) 144
d) 970

A

D

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7
Q

Opening force on a TXV is

a) spring pressure
b) bulb pressure
c) suction pressure
d) head pressure

A

b

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8
Q

TXV regulates freon flow to evap based on

a) heat of compression
b) suction SH
c) external equalizer pressure
d) evaporator pressure

A

b

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9
Q

An external equalizer is used when

a) press drop across evap is too great
b) liquid line press becomes too great
c) receiver is too full of freon
d) press drop at AXV is too great

A

A

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10
Q

When the load on the evap increases, the TXV

a) increases flow of freon
b) decreases flow of freon
c) maintains flow of freon
d) decreases press across evap

A

A

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11
Q

To determine SH with a blended freon, the correct formula is SH is equal to

a) measured vapour temp minus dew point temp
b) dew point measured minus measured vapour temp
c) measured vapour temp minus bubble point temp
d) bubble point temp minus measured vapour temp

A

a

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12
Q

To determine Sh with azeotropic (no glide), the correct formula is superheat is equal to

a) measured liquid temp minus sat temp
b) sat temp minus measured liquid temp
c) measured vapour temp minus sat temp
d) sat temp minus measured vapour temp

A

C

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13
Q

To determine SC with blended freon, the formula is

a) liquid temp minus dew point temp
b) dew point temp minus measured liquid temp
c) measured liquid temp minus bubble point temp
d) bubble point temp minus measured liquid temp

A

d

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14
Q

SC with azeotropic freon (no glide) the correct formula for SC is

a) measured liquid temp minus sat temp
b) sat temp minus measured liquid temp
c) measured vapour temp minus sat temp
d) sat temp minus measured vapour temp

A

b

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15
Q

In B52 code, a freon classification of A3 indicates

a) toxic freon that burns easily
b) non-toxic that burns easily
c) toxic that cannot be burned
d) non-toxic that cannot be burned

A

b

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16
Q

The term toxic as mused in B52 means

a) freon that causes damage to finished surfaces
b) freon that is dangerous to use in hermetic system
c) freon that is hazardous to human health
d) freon that causes damage to ozone

A

C

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17
Q

When converting a system from one freon to another, one must always

a) install new drier for new freon
b) check that the exp device will work
c) check with comp manufacturer for oil
d) all of the above

A

d

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18
Q

The term glide when referring to blended freon means

a) an alkyl benzene oil must be used
b) temp difference between dew point and bubble point at a constant pressure
c) amount that the txv must be calibrated
d) increase in discharge gas superheat

A

b

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19
Q

You would most likely find a 2000cfm blower on which of the following systems?

a) 2 ton AC system
b) 3 ton AC system
c) 5 ton AC system
d) 7.5 ton AC system

A

c

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20
Q

3412 btuh is equal to

a) 1 watt
b) 3.4 watt
c) 1 kilowatt
d) 3.4 kilowatt

A

c

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21
Q

Which of the following components is energized first in an intermittent ignition gas furnace on a call for heat?

a) induced draft motor
b) pilot gas valve
c) blower motor
d) main gas valve

A

a

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22
Q

A typical heat pump will have a high p switch to shut off if head pressure becomes excessive. The control action of this switch closes the contacts on pressure

a) rise at comp discharge
b) fall at comp discharge
c) difference between high and low side
d) total of high plus low press

A

b)

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23
Q

Which of the following is the correct formula for determining wattage in a resistive electrical circuit?

a) W=E times I
b) W=E/I
c) W=I/R
d) W= E x R

A

a

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24
Q

RPM of a motor is determined by

a) motors voltage
b) motors amperage
c) number of poles
d) the size of the motor windings

A

c

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25
Q

An ohmmeter reading of infinity across switch contacts means

a) switch is open
b) switch is closed
c) switch is good
d) switch is bad

A

a

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26
Q

Synchronous speed of a four pole motor is
(60hz)

a) 3600rpm
b) 1500rpm
c) 3450rpm
d) 1800rpm

A

d)

120 x 60 / 4=1800

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27
Q

Contactors are rated according to the maximum amperage through the

a) coil
b) contacts
c) thermostat
d) fuse

A

b

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28
Q

Lowering the airflow over a coil will

a) increase temp drop of the air and increase the amount of moisture removed from the air
b) decrease the temperature drop and increase amount of moisture removed from air
c) increase temp drop of air and decrease moisture removed from air
d) decrease temp drop of the air and decrease amount of moisture removed

A

a

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29
Q

Max secondary amperage of a 40VA, 240/24v control transformer is

a) 1.6amps
b) 6amps
c) 10.5amps
d) .16amps

A

a

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30
Q

Maintaining manufacturer specified clearances on al sides of equip is

a) necessary in residential applications only
b) necessary in commercial applications only
c) only necessary if required by code
d) always necessary no matter where installed

A

d

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31
Q

Of the following, which one would most likely be powered by a supply voltage of 240v single phase?

a) natural gas furnace
b) residential condensing unit
c) commercial packaged unit
d) residential humidifier

A

b

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32
Q

Which of the following would be the best place to mount a wall thermostat?

a) kitchen
b) bathroom
c) exterior wall
d) near return grill

A

d

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33
Q

Heat pump operating in heating mode with inadequate air flow across indoor coil will typically have which symptoms?

a) higher temp rise across outdoor coil
b) lower temp rise across outdoor coil
c) higher temp rise across indoor coil
d) lower temp rise across indoor coil

A

c

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34
Q

Condensate piping must be properly trapped to prevent:

A: Ice formation in colder temperatures

B: Condensate running off the evaporator coil

C: Condensate overflowing the drain pan

D: Excessive air noise in the piping

A

d

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35
Q

Which of the following components is typically used only on induced draft condensing gas furnaces?

A: Electronic fan control

B: Hot surface ignition

C: Induced draft blower motor

D: Secondary heat exchanger

A

d

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36
Q

7,000 BTU is approximately equal to _______ KW.

A: one

B: two

C: three

D: four

A

b

37
Q

Which precaution should an installer perform to keep copper from oxidizing internally while brazing a connector to the tube?

A: Hold the torch flame centered over the connector

B: Purge the tube with an inert gas such as nitrogen

C: Increase torch flame to its maximum setting

D: Hold the torch flame on the tubing only

A

b

38
Q

Charles law states

a) at constant pressure, volume of gas varies directly with absolute temp
b) total pressure of a confined mixture of gasses is the sum of pressure of each of the gasses in mixture
c) volume of gas varies indirectly with absolute temp
d) volume of gas inversely with absolute pressure if the temperature remains constant

A

A

39
Q

Compressor ratio?

a) discharge psia/suction psia
b) suction psia/ discharge psia
c) discharge psig/suction psig
d) suction psig/discharge psig

A

a

40
Q

Where in system is excess SH added that must be removed before condensation in the condenser can take place?

a) start of evap and end of receiver
b) end of receiver beginning of txv
c) beginning of evap and in comp
d) at end of evap and in comp

A

d

41
Q

Fresh air intake ducts used to route outdoor air into interior spaces, connects to the

a) vent piping
b) combustion air duct
c) supply side of system
d) return side of system

A

d

42
Q

Daltons law

a) constant press, volume of gas varies directly with absolute temp
b) total press of a confined mixture of gases is the sum of the pressures of each of the gases in the mix
c) volume of gas varies indirectly with absolute temp
d) volume of gas inversely with absolute pressure if the temperature remains constant

A

b

43
Q

What is the temp rise of a 250cfm of air if an electric heater adds 8500btuh to the air?

a) 18f
b) 27f
c) 31.5f
d) 40f

A

c

44
Q

What are three commonly used metering devices for residential and light commercial air con?

a) TXV, AXV, Low side float
b) High side float, low side float, cap tube
c) lo side float, piston type, AXv
d) cap tube, piston type, txv

A

d

45
Q

External equalizer connection to the suction line, should be located

a) next to TXV sensing bulb
b) 6-8 inches upstream of TXV bulb
c) 6 to 8 inches downstream of txv bulb
d) none of the above

A

c

46
Q

Which of the following refrigerants is a HCFC?

a) R12
b) R-22
c) R-502
d) R-134A

A

b

47
Q

Heat pump working ok until defrost cct energized. Defrost stays for ten min when there is no ice on the coil. What is cause?

a) defrost timer defective
b) defrost termination stat stuck closed
c) defrost termination stat stuck open
d) reversing valve solenoid stuck open

A

b

48
Q

What are symptoms of an air condition system w low charge?

a) evap coil will be partially frosted and discharge pressures will incraase
b) suction will set and low side pressure will decrease
c) low side pressure will decrease and evap coil will be partially frosted
d) discharge pressure will decrease and suction pressure will increase

A

c

49
Q

With belt driven equipment, alignment of the motor and drive equipment pulleys

a) is not critical since belts are flexible
b) is accomplished using a string or straight edge
c) is accomplished when belts are parallel to one another
d) is accomplished using a dial indicator

A

b)

50
Q

10 in Hg. vacuum is equal to?

a) 5psig
b) 5psia
c) 10psig
d) 10psia

A

d

51
Q

Compressor capacity controlled by cylinder unloading method:

a) may result in comp overheating
b) is used only with hermetic compressors
c) does not provide energy savings
d) is used only more systems charged with ammonia

A

a

52
Q

Most compressors are positive displacement machines. Name a comp that is not positive displacement

a) reciprocating
b) helical-rotary (screw)
c) rotary
d) centrifugal

A

d

53
Q

Ratio of actual volume of vapour pumped to the theoretical displacement volume is known as:

a) volumetric efficiency
b) volumetric ratio
c) compression efficiency
d) compression ratio

A

a

54
Q

A compressor in which the compressor and motor are both sealed within the same pressurized housing is known as?

a) a sealed compressor
b) pressurized compressor
c) hermetic compressor
d) semi-hermetic compresor

A

c)

55
Q

The passage of liquid refrigerant through the compressor suction and discharge valves should be avoided and is known as

a) choking the compressor
b) slugging the compressor
c) kicking the compressor
d) shocking the compressor

A

b

56
Q

Compressor capacity decreases as

a) discharge pressure increases
b) suction pressure decreases
c) compressor speed decreases
d) all of the above

A

d

57
Q

Scroll compression does what?

a) vapour enters the outside and exits the centre
b) vapour enters the centre of scroll and exits outside
c) vapour enters from one side and exits from the other side
d) both a and c

A

a

58
Q

Capacity control on helical-rotary (screw) compressor is obtained using

a) inlet vanes
b) hot gas bypass
c) variable speed motors
d) sliding valve

A

d

59
Q

Bearings in an operating centrifugal compressor can be checked by

a) sliding the impeller back and forth for slop
b) trying to move shaft at right angles to the bearing
c) checking temp of oil returning from bearing
d) manually spinning the impeller and listening for grinding

A

c

60
Q

A decrease in condensing temp will

a) increase condensing pressure, increases suction temp and increase capacity
b) decrease condensing pressure, increase suction temp, increase capacity
c) decreasing condensing pressure, decreases suction temp and increase system capacity
d) decrease condensing pressure, decrease suction, decrease capacity

A

c

61
Q

Subcooling in the condenser will

a) increase system capacity
b) decrease system capacity
c) not affect it
d) increase flash gas

A

a

62
Q

Rule of thumb: every 12k btu of cooling capacity in an open drive compressor air conditioning system, heat rejection is roughly

a) 12kbtuh or 1.0 times the net refeff
b) 9k btu or .75 times net ref effect
c) 15k btu or 1.25 times net ref eff
d) none of above

A

c

63
Q

A possible cause of high head pressure is

a) dirty condenser tubes
b) insufficient water flow through condenser
c) air and non-condensables in the condenser
d) all of the above

A

d

64
Q

Calculate the amount of water needed per ton of refrigeration in a water cooled condenser assuming a heat rejection rate of 15,000btuh/ton and a 20f water temp rise through the condenser (US gallons)

a) 0.15gpm
b) 0.45gpm
c) 1.5gpm
d) 4.5gpm

A

GPM = btu / (water td x 500)

15,000/10,000 = 1.5gpm?

65
Q

In order to protect a load, safety limit devices are often wired in

a) parallel
b) series
c) upstream
d) downstream

A

b

66
Q

A flow switch safety control is used to

a) control amount of flow of a fluid (liquid or gas)
b) turn on pump or fun
c) divert fluid flow during unsafe conditions
d) prove that flow is occurring

A

d

67
Q

What is a disadvantage of a mercury bulb switch?

a) unreliable
b) must be level
c) tend to burn contacts
d) tend to chatter which cycles load on and off

A

b

68
Q

A thermostat is calibrated when

a) set point and control point are equal
b) room temp is comfortable
c) there is no dead band
d) control point and thermometer reading are equal

A

a

69
Q

With a change in temperature, a thermistor will change

a) resistance
b) voltage
c) current
d) impedance

A

a

70
Q

One type of pressure sensing device uses a flattened metal tube, which is bent into a part circle with one end fixed in place and connected to the pressure to be measured. Other end is free to move. Increase in pressure straightens the tube.

a) whiskey tube
b) bimetal tube
c) bourdon tube
d) flat-tube ache

A

c

71
Q

In a TXV, evap pressure acts to _____ the valve, spring pressure acts to ______ the valve, bulb pressure acts to _____ the valve

A

close, close, open

72
Q

A common indication of a defective potential starting relay on a single phase motor is?

a) motor hums but does not start
b) motor starts, runs normally, then shuts down after several min
c) motor does not come up to speed
d) motor starts but runs in wrong direction

A

a

73
Q

Level of voltage caused by the back electromotive force that opens the contacts on a potential relay is called

a) lift voltage
b) open voltage
c) run voltage
d) pick up voltage

A

d

74
Q

A refillable refrigerant cylinder must not be filled above percent of its capacity by weight

a) 90%
b) 80%
c) 70%
d) 60%

A

b

75
Q

As the evaporating temp of any vapour compression system is lowered

a) compressor suction vapour density increases
b) volume of suction vapour decreases
c) compressor capacity is lowered
d) flash gas is likely to occur in the liquid line

A

C

76
Q

When charging a chilled water system, charging is done as a liquid. However, if the machine is in a deep vacuum, the initial charge should be done as vapour, why?

a) faster because system in vacuum
b) charging vapour prevents thermal shock to system
c) charging as vapour until system reaches ambient prevents condensation in system
d) charging until system temp rises above 32f prevents freezing of water in the tubes

A

d

77
Q

In order to charge by subcooling monitor discharge pressure and liquid line temp close to metering device and charge until liquid line temp falls below the discharge saturation temp by the expected amount of subcooling. T or F?

A

T

78
Q

A special valve used to prevent evaporator temperature from falling below a predetermined minimum temperature regardless of suction pressure is the

a) evaporator pressure regulator
b) pressure reducing valve
c) suction pressure regulator
d) none of the above

A

A

79
Q

In general, the greater the number of rows in an evaporator:

a) more closely the leaving air temp will be to that of the refrigerant
b) more dehumidification
c) colder leaving air will be
d) all

A

d

80
Q

Increasing air flow over an evaporator will

a) increase evaporator capacity
b) decrease evaporator capacity
c) does not affect evaporator capacity
d) none of the above

A

a

81
Q

A hermetic motor should never be energized or tested with a megger while in a deep vacuum because

a) electric arcs can contaminate refrigerant in the system
b) motor could draw too much amperage
c) vacuum pump could be damaged
d) dielectric strength of the motors insulation would be greatly reduced

A

d

82
Q

A term used to rate vacuum pumps is used to describe the pumps ability to draw a vacuum. Pump must create a vacuum within itself that is lower than a system, so that gases will flow from system to the pump. Point at which the pump can no longer create a pressure difference is the

a) dead head pressure
b) blank off pressure
c) blocked tight static pressure
d) point of no pressure difference

A

b

83
Q

Oil pressure safety is operated by

a) oil pressure alone
b) sum of oil pump discharge and crankcase pressure
c) difference between crankcase pressure and oil pump discharge pressure
d) difference between head pressure and oil pump discharge pressure

A

c

84
Q

In order for an oil failure control to operate correct it must be wired so that it gets power to the heater circuit

a) at all times
b) only when comp is on
c) only when comp has good oil p
d) after an oil change

A

b

85
Q

When the compressor has adequate oil pressure the contacts between L and M are

a) open
b) closed
c) closed then open
d) open then closed

A

B

86
Q

The most common cause of low oil pressure is

a) oil pump failure
b) low oil level
c) incorrect oil
d) too large crankcase heater

A

A

87
Q

A step down transformer has a 10ohm resistor connected across the 240v secondary winding. If the primary current is 6amps what is the primary voltage?

a) 240v
b) 480v
c) 960v
d) 1920v

A

c

volts x amps
6x240=960v

88
Q

The coil of a current relay is open. The compressor has a start capacitor but no run capacitor. Th problem noted with the compressor is

a) overload trips due to high current in the start winding
b) compressor draws no current and fails to start
c) compressor starts only if the system pressures equalize
d) compressor starts and runs normally

A

b

89
Q

If the temp of the air being handled by a forward curved fan is reduced substantially

a) cfm will increase
b) static pressure will increase
c) cfm will decrease
d) motor amperage increase

A

d) increase because density

Term 3 - Review Tests (9 decks)

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