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FINAL PWEN ABSA PRACTICE 4 > FINAL PWEN ABSA PRACTICE 4 > Flashcards

FINAL PWEN ABSA PRACTICE 4 Flashcards

1
Q

The term “prime mover” refers to:

a. All heat engines
b. A single device that either by itself or as part of a system converts a natural source of energy into motion
c. Electric motors
d. Steam turbines
e. Large steam generators

A

b. A single device that either by itself or as part of a system converts a natural source of energy into motion

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2
Q

The shafts of high output, high temperature steam turbines are usually sealed by using:

a. High pressure air seals
b. Carbon rings
c. Water sealed glands
d. Oil sealed glands
e. Labyrinth glands

A

e. Labyrinth glands

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3
Q

In an impulse turbine the:

a. Steam flow is reduced through the nozzles
b. Steam pressure is reduced in the nozzles
c. Steam pressure will drop across the blades
d. Steam velocity is increased through the blades
e. Exhaust steam is directed back to the boiler

A

b. Steam pressure is reduced in the nozzles

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4
Q

A gas turbine is not self-starting. It must be rotated at _____ of its maximum speed before fuel is turned on.

a. 10% to 30%
b. 15% to 30%
c. 20% to 30%
d. 25% to 30%
e. 25% to 50%

A

c. 20% to 30%

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5
Q

Compression tests should be taken at regular intervals on diesel engines to check for possible development of:

a. Coolant leaks
b. Low torque
c. Fouled glow plugs
d. Overheating
e. Blow by.

A

e. Blow by.

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6
Q

Condensing turbines:

a. Are always impulse turbines
b. Will have a vacuum in the last row of rotating blades
c. Will use the condensate for heating
d. Are very small units
e. Cannot have counter flow stages.

A

b. Will have a vacuum in the last row of rotating blades

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7
Q

A closed cycle gas turbine:

a. Does not need a combustion chamber
b. Must use a cooler before the regenerator
c. Will use the same working fluid over again
d. Is a self-starting type of gas turbine
e. Starts with the exhaust valve closed

A

c. Will use the same working fluid over again

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8
Q

Cooling towers:

a. Remove the heat from the condensate
b. Prevent thermal pollution of rivers and lakes
c. Cannot be used during winter periods
d. Are used with steam turbines only
e. Reduce flue gas temperatures.

A

b. Prevent thermal pollution of rivers and lakes

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9
Q

A two-cycle engine:

a. Must always have lube oil premixed with the fuel
b. Can never have a crankcase lubrication system
c. Gives one power-stroke every other crankshaft revolution
d. “Pops” twice as often as an equivalent cylinder four-stroke engine
e. Can never be operated in an inverted position

A

d. “Pops” twice as often as an equivalent cylinder four-stroke engine

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10
Q

Centrifugal pumps do not develop good suction lift because:

a. Atmospheric pressure is usually too low
b. The pumped medium relative density is too high
c. Their internal component clearances are too high
d. The speed is too low
e. They favor pressure rather than volume.

A

c. Their internal component clearances are too high

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11
Q

You discover that your feed water pump is not delivering sufficient water. A possible cause is:

a. The impeller is plugged
b. The suction lift is too low
c. The discharge head is not high enough
d. There is too much water in the pump
e. The foot valve is fully open.

A

a. The impeller is plugged

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12
Q

Turbine pumps are best suited for:

a. Low capacity low-pressure service
b. Low capacity high-pressure service
c. High capacity high-pressure service
d. High capacity low-pressure service
e. Heavy viscous fluids.

A

b. Low capacity high-pressure service

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13
Q

A positive displacement stand by pump will have the:

a. Vent and drain valves open
b. Suction valve closed and the discharge valve open c. Suction valve open and the discharge valve closed d. Suction valve and the discharge valve open
e. Suction valve and the discharge valve closed

A

b. Suction valve closed and the discharge valve open

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14
Q

A mechanical pump seal:

a. Will have a substantial amount of leakage
b. Will cause more wear on the shaft than a packing seal
c. Is used for high pressure service
d. Does not need cooling
e. Is used in reciprocating pump service

A

c. Is used for high pressure service

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15
Q

To prime a centrifugal pump you must:

a. Clean the oil ring
b. Fill the housing with liquid
c. Be sure to bypass the impeller
d. Run the pump at half speed
e. Fill the pump casing with compressed air

A

b. Fill the housing with liquid

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16
Q

If an oil’s viscosity changes much with little temperature change, it will then have a:

a. Low viscosity index
b. High pour point
c. High carbon residue
d. High viscosity index
e. Low pour point

A

a. Low viscosity index

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17
Q

Which of the following has the greatest effect on the viscosity of lubrication oil?

a. Pressure
b. Load
c. Flow
d. Temperature
e. Speed.

A

d. Temperature

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18
Q

When 1 ampere of current flows through a resistance by the application of 1 volt the resistance will be 1:

a. Watt
b. Joule
c. Kilowatt
d. Ampere
e. Ohm.

A

e. Ohm

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19
Q

The voltage required to force a current of 15 amps through a resistance of 5 ohms will be _____ volts.

a. 0.33
b. 3
c. 7.5
d. 33
e. 75.

A

e. 75.

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20
Q

What is the current flow when a voltage of 110 volts is applied to a circuit of 20 ohms?

a. 0.1818 amperes
b. 0.22 amperes
c. 18.18 amperes
d. 5.5 amperes
e. 55 amperes.

A

d. 5.5 amperes

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21
Q

The capacity of a transformer can be increased by:

  1. Submerging the core and windings in a tank of oil
  2. Submerging the core and windings in a tank of water 3. Forced air cooling the oil in a heat exchanger
  3. Wrapping the core with a thermal insulation
  4. Forced air cooling of the core

a. 1, 3, 5
b. 2, 3, 4
c. 1, 4, 5
d. 2, 3, 4, 5
e. 2, 4, 5

A

a. 1, 3, 5

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22
Q

When grease is used in an antifriction bearing, the bearing housing should not be filled more than _____ full.

a. 1/4
b. 1/3
c. 1/2
d. 3/4
e. Completely

A

b. 1/3

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23
Q

Oils with a low pour point should be used in:

a. Hot climates
b. Cold climates
c. Climates that have drastic temperature changes
d. Temperatures of a climate that does not matter
e. High humidity situations.

A

b. Cold climates

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24
Q

Fluid film lubrication:

a. Is used for heavy loads
b. Removes all friction in the bearing
c. Is used in all anti-friction bearings
d. Is used during low ambient temperature conditions e. Is used for light loads.

A

a. Is used for heavy loads

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25
Q

Compressor unloaders:

a. Could close the discharge valve
b. Must be used on centrifugal compressors
c. Could keep the suction valve open
d. Activate the stop and start button
e. Are located on the driver of the compressor

A

c. Could keep the suction valve open

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26
Q

When a conductor is moved to cut magnetic flux lines at an angle of 90 degrees:

a. Maximum resistance to current flow is attained
b. Current will flow with the least resistance
c. Motor action will be experienced
d. Voltage generated will be maximum
e. Motion will be easiest.

A

d. Voltage generated will be maximum

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27
Q

Intercoolers:

a. Must have a drain
b. Are more efficient when cooled with air than with water
c. Are used on double acting single stage compressors d. Help increase the volume of the air
e. Should use an antifreeze solution

A

a. Must have a drain

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28
Q

A rheostat or “voltage regulator” of a DC shunt wound generator is used to:

a. Regulate the strength of the electromagnetic field
b. Regulate the speed of the generator
c. Regulate the current to the load
d. Change the AC to DC
e. Change the unit into a DC motor.

A

a. Regulate the strength of the electromagnetic field

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29
Q

When current flows in a conductor:

a. AC voltage is generated
b. The voltage is reduced in the conductor
c. No heat can be generated
d. A circular magnetic field is set up around the conductor
e. All magnetic forces are dissipated

A

d. A circular magnetic field is set up around the conductor

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30
Q

The battery of an electrical circuit:

a. Gives a load to the circuit
b. Withholds neutrons from the circuit
c. Supplies the electromotive force
d. Maintains lighting for the circuit
e. Decreases the resistance.

A

c. Supplies the electromotive force

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31
Q

Ammeters are connected:

a. In parallel with the circuit
b. In series with the circuit
c. In parallel with the circuit to measure the resistance d. So that voltage will bypass the meter
e. To the negative and positive terminals of the battery.

A

b. In series with the circuit

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32
Q

The coils or windings on a DC machine armature are placed in _____ cut in the face of the armature.

a. Bars
b. Holes
c. Pairs
d. Sequence
e. Slots.

A

e. Slots.

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33
Q

The _____ number of oil indicates the acidity of oil.

a. pH
b. Acidity
c. Alkalinity
d. Neutralization
e. Viscosity index

A

d. Neutralization

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34
Q

A proportional controller:

  1. Has the same function whether it is pneumatic or electronic
  2. Provides a proportional output based on the error between process variable and setpoint
  3. Requires no operator input
  4. Provides on off control
  5. Is typically something the operator cannot touch

a. 1
b. 1, 2
c. 1, 2, 3
d. 1, 2, 4
e. 1, 2, 5.

A

b. 1, 2

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35
Q

A transformer works on the principle of:

a. Reverse polarity
b. Magnetic induction
c. DC power flowing in one direction
d. Straight polarity
e. Automatic induction

A

b. Magnetic induction

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36
Q

A device which will cause a visible light signal to become an instrument analog signal is the:

a. Photoelectric transducer
b. Transferor
c. Controller
d. Final element
e. Current-to-pneumatic transducer

A

a. Photoelectric transducer

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37
Q

Tie circuit breakers are used to:

a. Allow the interconnection of two power sources without placing them in parallel
b. Break the circuit in case of overload
c. Protect the transformer from the power source
d. Protect the plant service bus from the power source e. Connect the plant load to the power source.

A

a. Allow the interconnection of two power sources without placing them in parallel

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38
Q

Level, pressure, flow, temperature, composition, vibration, speed and clearance are all examples of:

a. Transmitters
b. Control variables
c. Sensing elements
d. Disturbances
e. Manipulated variables

A

b. Control variables

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39
Q

Thrust bearings:

  1. Are used on reaction turbines
  2. Prevent the turbine rotor from moving axially
  3. Are always installed on both ends of the rotor shaft 4. Are lubricated with the same oil as the main bearings

a. 1, 2, 4
b. 2, 3, 4
c. 1, 2, 3
d. 1, 3, 4
e. 1, 2, 3, 4

A

a. 1, 2, 4

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40
Q

Which of the following boilers is considered a single pass boiler?

  1. HRT boiler
  2. Scotch marine boiler
  3. Packaged firetube boiler
  4. Vertical firetube boiler
  5. Steel plate heating boiler

a. 1, 4
b. 1, 2
c. 1, 3
d. 2, 5
e. 4, 5.

A

e. 4, 5.

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41
Q

Orifice plates, venturi tubes and nozzles belong to the group called:

a. Flow meters
b. Pressure meters
c. Head meters
d. Analog meters
e. Constant output meters

A

c. Head meters

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42
Q

A thermo hydraulic feed water regulator uses _____ as mediums.

a. Oil and nitrogen
b. CO2 and water
c. Water and steam
d. Mercury and zinc
e. Air and water

A

c. Water and steam

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43
Q

A combustion air proving switch:

a. Senses O2 content of the air
b. Senses flue gas pressure
c. Detects O2 in flue gas
d. Senses windbox pressure
e. Senses air temperature

A

d. Senses windbox pressure

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44
Q

Computer output is put through a/an _____ before an analog control can react to the signal.

a. Digital receiver
b. Logic controller
c. Modem
d. Analog converter
e. Integrated circuit

A

d. Analog converter

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45
Q

Calculate the height in meters between the water surface in an elevated tank and the ground to create a pressure of 335 kPa.

a. 13.133 m
b. 18.431 m
c. 34.170 m
d. 37.087 m
e. 39.936 m

A

c. 34.170 m

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46
Q

Automatic boiler programming controls:

a. Must incorporate a modulating control system
b. Are not interconnected with the water level control system
c. Require an ON-OFF or two-position control switch
d. Cannot make use of high-low fire control
e. Do not require interlocking devices

A

c. Require an ON-OFF or two-position control switch

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47
Q

The function of a flame failure device is to:

a. Shut off the fuel supply when the pressure gets too high
b. Shut off the fuel when the burner flame goes out
c. Shut off the fuel when the temperature is high
d. Shut off the feed water supply to the boiler
e. De-energize the fan and feed water system

A

b. Shut off the fuel when the burner flame goes out

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48
Q

Inputs for logic and supervisory computer functions are mainly:

a. By switch contacts
b. Actions of an operator using the keyboard
c. Stored on a disk which is required for operation
d. Controlled by relays
e. Non-decision making

A

a. By switch contacts

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49
Q

To check the pilot flame system on an automatically fired boiler:

a. Close fuel valves while boiler is operating
b. Close fuel valves prior to start up
c. Remove and cover scanner during pilot operation
d. Simulate a low water condition
e. Observe pilot during purge period.

A

b. Close fuel valves prior to start up

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50
Q

A valve which has two seats, gives good throttling action, but does not seal well is a:

a. Double seated valve
b. Reverse acting valve
c. Reverse seated valve
d. Single seated valve
e. Direct acting valve

A

a. Double seated valve

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51
Q

An initial problem with the tubular boiler being used as a steam unit was:

a. Metals that would not stand up to the temperatures involved
b. Dissolved impurities forming scale on the tube
c. Metals not standing up to the pressures involved
d. Inadequate capacities
e. Inability to maintain pressure

A

b. Dissolved impurities forming scale on the tube

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52
Q

Thermocouples require:

a. A non-metallic strip or coil
b. A thermopile
c. Two dissimilar metals
d. An elliptical sectioned tube
e. A heating element

A

c. Two dissimilar metals

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53
Q
  1. To test a low water fuel cut-off:

a. Call for an electrician who specializes in boiler controls
b. Lower the water level until the burner shuts down
c. Connect an ammeter to the mercury switch
d. Test the water column with a test gage
e. Shut off the fuel to the boiler

A

b. Lower the water level until the burner shuts down

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54
Q

Low-pressure heating boilers are those that operate below:

a. 25 kPa
b. 50 kPa
c. 76 kPa
d. 100 kPa
e. 103 kP

A

d. 100 kPa

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55
Q

Cast iron boiler sections maximize heat transfer by:

a. Utilizing as few passes as possible
b. Vertical firing
c. Exposing as large a surface as possible to the hot gases
d. Utilizing an external furnace
e. Using four push nipples per section.

A

c. Exposing as large a surface as possible to the hot gases

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56
Q

In order to produce the strength of magnetic flux required in larger DC machines:

a. Electro magnets are used
b. Copper switches are used
c. Permanent magnets are used
d. The field windings are double-wound
e. Booster transformers are used

A

a. Electro magnets are used

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57
Q

The compressed air used as atomizing air in the air atomizing oil burner is also called:

a. Secondary air
b. Primary air
c. Pre-mixed air
d. Pre-compressed air
e. Post-compressed air

A

b. Primary air

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58
Q

A steam heating boiler safety valve lever test should be performed:

a. Weekly
b. Semi-annually
c. Monthly
d. Daily
e. Quarterly

A

c. Monthly

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59
Q

The Venturi tube in the atmospheric burner mixing head has a:

a. Gradually decreasing cross-sectional area
b. Gradually increasing cross-sectional area
c. Sharply decreasing cross-sectional area
d. Sharply increasing cross-sectional area
e. Uniformly distributed cross-sectional area.

A

b. Gradually increasing cross-sectional area

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60
Q

A solenoid type fuel valve;

a. Is held closed by fuel pressure
b. Always opens rapidly
c. Is held closed by electrical current
d. Closes slowly
e. Does not have positive shut-off.

A

a. Is held closed by fuel pressure

61
Q

When a closed expansion tank is used and the system is cold:

a. The auto fill valve will maintain a system minimum pressure
b. The tank level will be high
c. There will be no air in the tank
d. The possibility of air in the system will be high
e. The tank should be manually filled.

A

a. The auto fill valve will maintain a system minimum pressure

62
Q

Which of the following are the most commonly used electric infrared heaters?

  1. Low temperature catalytic heater
  2. Metal sheath element
  3. Internally-fired heater
  4. Quartz tube heater
  5. Quartz lamp

a. 1, 2, 3
b. 2, 3, 4
c. 3, 4, 5
d. 1, 3, 5
e. 2, 4, 5

A

e. 2, 4, 5

63
Q

Intermediate and high fire burner nozzles have higher capacities than the primary burner nozzle:

a. To give greater firing variations
b. To prevent pressure surges
c. To prevent ignition puff-backs
d. Because of the pump being of the positive displacement type
e. To allow better boiler warm-ups.

A

e. To allow better boiler warm-ups.

64
Q

According to the current code no safety valve on a steam heating boiler shall be larger than:

a. 25.4 mm (1 in)
b. 38.1 mm (1 ½ in)
c. 50.8 mm (2 in)
d. 63.5 mm (2 ½ in)
e. 115 mm (4 ½ in).

A

c. 50.8 mm (2 in)

65
Q

One of the main disadvantages of electrical heating systems is:

a. High operating cost
b. High installation cost
c. High maintenance cost
d. Temperature control
e. Pollution

A

a. High operating cost

66
Q

The water column drain pipe and valve on a steam heating boiler shall not be less than:

a. 75 mm
b. 51 mm
c. 20 mm
d. 15 mm
e. 10 mm

A

b. 51 mm

67
Q

If a heating boiler with an automatic feedwater system requires a large amount of water to be fed manually, this may indicate:

a. You are producing a great deal more steam
b. There is probably a leak in the system
c. There has been a drastic change in the water quality d. Your return lines are not working
e. The flow meter is not working properly.

A

b. There is probably a leak in the system

68
Q

How many pressure relief valves shall a hot water heating boiler have?

a. None
b. At least one
c. At least two d
d. At least three
e. At least four

A

b. At least one

69
Q

Advantages of the high temperature hot water systems are:

a. Reduction in pipe size and greater heat storage capacity
b. Low water make-up and better temperature control c. High vacuum in the return lines and pumps
d. Higher make-up and better chemical control
e. High-pressure piping and controls.

A

a. Reduction in pipe size and greater heat storage capacity

70
Q

Ventilation can be divided into two basic methods:

a. Forced and natural
b. Mechanical and natural
c. Forced and mechanical
d. Natural and warmed air
e. Natural and cold air

A

b. Mechanical and natural

71
Q

A test lead or “jumper wire” is required when testing:

a. High steam pressure or water temperature limiting controls
b. A high gas pressure fuel cut-off switch
c. A safety valve with the test lever
d. The low water fuel cut-off switch
e. A low gas pressure fuel cut-off.

A

a. High steam pressure or water temperature limiting controls

72
Q

Unit ventilators use:

a. Only outside air for heating
b. Only inside air for heating
c. Natural draft
d. A mixture of inside and outside air for heating
e. Fin coil heaters

A

d. A mixture of inside and outside air for heating

73
Q

Which one of the following steam heating systems can be used to overcome the difficulty of returning condensate back to the boiler due to inefficient static head?

a. One pipe, gravity return system
b. Two pipe, gravity return system
c. One pipe, free flow return system
d. Two pipe, return trap system
e. Two pipe, free drain return system

A

d. Two pipe, return trap system

74
Q

In the case of radiators and convectors, the main sources of trouble are the:

a. Air vents
b. Air traps
c. Push nipples
d. Connecting rods
e. Valves and traps.

A

e. Valves and traps.

75
Q

The minimum pressure rating of valves and cocks used for blowoff or drain purposes on a steam or hot water heating boiler shall be at least equal to the pressure stamped on the boiler but in no case less than:

a. 100 kPa
b. 150 kPa
c. 200 kPa
d. 250 kPa
e. 300 kPa

A

c. 200 kPa

76
Q

An essential fitting between the boiler and the steam pressure gauge is a:

a. Check valve
b. Gate valve
c. Gauge glass
d. Siphon
e. Steam trap.

A

d. Siphon

77
Q

Dual temperature thermostats are set at two different temperatures and the transfer from one to the other is made by, changing the supply air pressure from:

a. 3 kPa to 15 kPa
b. 5 kPa to 25 kPa
c. 20 kPa to 90 kPa
d. 0 kPa to 100 kPa
e. 100 kPa to 125 kPa

A

e. 100 kPa to 125 kPa

78
Q

A bimetal thermostat’s operating range is between:

a. 5 and 40°C
b. 0 and 50°C
c. 0 and 40°C
d. 10 and 32°C
e. 50 and 90°C

A

d. 10 and 32°C

79
Q

A direct acting controller:

a. Increases its output signal on an increased input signal.
b. Increases its output signal on a decreased input signal.
c. Increases its output signal on an increased output signal.
d. Increases its input signal on an increased output signal.
e. Decreases its output signal on an increased input signal.

A

a. Increases its output signal on an increased input signal.

80
Q

Which of the following is a type of outlet in a warm air heating system?

a. A grill
b. A register
c. A ceiling diffuser
d. A perforated panel
e. All of the above.

A

e. All of the above.

81
Q

Upon starting a cold gas-fired boiler water initially may leak from the reversing chambers due to:

a. The fire tubes not expanding into the tube sheets
b. A fire tube has failed
c. Combustion gasses are condensing on cold boiler surfaces
d. There is boiler water on the fire side of the fire tubes
e. The fireside was just hydro teste

A

c. Combustion gasses are condensing on cold boiler surfaces

82
Q

Ambient lighting can be improved by using two types of lighting:

a. Direct and indirect
b. Natural and artificial
c. Florescent and incandescent
d. Reflective and refractive
e. General and local

A

a. Direct and indirect

83
Q

A deep seal, plumbing trap has a water seal depth of:

a. 5 cm
b. 10 cm
c. 15 cm
d. 20 cm
e. 25 cm.

A

b. 10 cm

84
Q

Which of the following are principal parts in a closed cycle compression refrigeration system?

  1. Absorber
  2. Evaporator
  3. Compressor
  4. Condenser

a. 1, 2
b. 3
c. 1, 2, 4
d. 2, 3, 4
e. 1, 2, 3

A

d. 2, 3, 4

85
Q

The temperature control on a steam to hot water converter, controls the:

a. Pump speed
b. Steam temperature
c. Water flow
d. Steam control valve
e. Firing rate.

A

d. Steam control valve

86
Q

A device found on the pressure side of a boilers operating control switch is a:

a. Modutrol motor
b. Siphon
c. Combustion air proving switch
d. Test connection for an inspector
e. Feedwater pressure gag

A

b. Siphon

87
Q

The maximum allowable temperature for the water in a hot water heating boiler is:

a. 100°C
b. 150°C
c. 121°C
d. 170°C
e. 250°C.

A

c. 121°C

88
Q

When filling a hot water system prior to putting it into service, it is most important to:

a. Close all valves and fill the system quickly
b. Purge the boiler
c. Remove the safety valve
d. Vent all air
e. Check the gage glass on the boiler

A

d. Vent all air

89
Q

One tonne of refrigerant is:

a. 13958 kJ per day
b. 100 kJ per minute
c. 233 kJ per minute
d. 13958 J per hour
e. 335 J per second

A

c. 233 kJ per minute

90
Q

The heat used to change the state of a substance, is called:

a. Superheat
b. Convection heat
c. Radiant heat
d. Conduction heat
e. Latent heat.

A

e. Latent heat.

91
Q

On a multiple steam boiler heating system, a stop valve must be placed at each boiler outlet to:

a. Permit slower system warm-ups
b. Allow the boiler to be isolated from the system
c. Prevent steam from entering another boiler
d. Allow each boiler to supply only a part of the system e. Permit different system pressures

A

b. Allow the boiler to be isolated from the system

92
Q

Building codes recommend that nowhere in a building plumbing system should the water pressure fall below:

a. 100 kPa
b. 175 kPa
c. 350 kPa
d. 490 kPa
e. 560 kPa.

A

b. 175 kPa

93
Q

In a refrigeration system, the purpose of the compressor is to:

a. Establish two pressure levels
b. Reject the heat from the system
c. Absorb the heat into the system
d. Regulate the flow of the refrigerant
e. Heat the refrigerant.

A

a. Establish two pressure levels

94
Q

The operating control which uses a bimetal element is a:

a. Fluid expansion actuating control
b. Pressure actuated control
c. Humidity actuated control
d. Temperature actuated control
e. Solenoid actuated control

A

d. Temperature actuated control

95
Q

The emergency discharge line in a refrigeration system:

a. Is located only on the condenser
b. Should have a emergency valve outside the building
c. Is required on all sizes of refrigeration systems
d. Is located on the evaporator
e. Is a vented sewer line.

A

b. Should have a emergency valve outside the building

96
Q

R-22 (Freon-22) is non-toxic and non-flammable. Which of the following groups does it belong to?

a. Group A2
b. Group B4
c. Group A1
d. Group A3
e. Group B2.

A

c. Group A1

97
Q

Ammonia is the only commonly used refrigerant that has the physical property of:

a. Miscibility
b. Enthalpy
c. Flammability
d. Density
e. Low condensing pressure

A

c. Flammability

98
Q

The initial refrigerant charge is given where on the system?

a. The high side of the system
b. The low side of the system
c. The evaporator
d. The expansion valve
e. The heat exchanger

A

a. The high side of the system

99
Q

Oil separators in refrigeration systems:

a. Discharge oil back into the compressor crankcase
b. Are fitted to the purge line
c. Must be water, cooled
d. Require a relief valve
e. Remove oil from the charging valve

A

a. Discharge oil back into the compressor crankcase

100
Q

Enthalpy of air depends on the:

a. Pressure, temperature and relative humidity of the air.
b. Relative humidity of the air only.
c. Pressure and temperature of the air only.
d. Air velocity.
e. Temperature of the air only

A

a. Pressure, temperature and relative humidity of the air.

101
Q

The Hartford loop will:

a. Eliminate the need for venting a steam heating system
b. Ensure continuous circulation of a hot water system c. Prevent steam from entering a steam pressure gage d. Prevent boiler water level from going below the lowest safe water level
e. Prevent the draining of an expansion tank

A

d. Prevent boiler water level from going below the lowest safe water level

102
Q

The most widely used refrigerant control which consists of a bellows, or a diaphragm chamber connected to a temperature sensing bulb by means of a small capillary tube is a/an:

a. Thermostatic expansion valve
b. Automatic expansion valve
c. Low pressure float valve
d. Hand operated expansion valve
e. High pressure float valve

A

a. Thermostatic expansion valve

103
Q

If 5.0 cubic meters per second of air enters a heating coil at 20° C dry bulb and 15° C wet bulb, and leaves the heating coil at 30° C dry bulb, what is the mass of air flowing?

a. 5.94 kg/s
b. 6.84 kg/s
c. 5.0 kg/s
d. 6.2 kg/s
e. 5.4 kg/s

A

a. 5.94 kg/s

104
Q

Velocity pressure exerted by the air is measured by connecting a:

a. Manometer at right angles to the air duct.
b. Manometer in the air duct with the inlet opening facing into the air, flow and the outlet opening at right angles to the air duct.
c. Manometer to the fan.
d. Bourdon tube pressure gage to the air duct.
e. Pressure gage at right angles to the air duct.

A

b. Manometer in the air duct with the inlet opening facing into the air, flow and the outlet opening at right angles to the air duct.

105
Q

If 5.0 cubic meters per second of air enters a heating coil at 20° C dry bulb and 15° C wet bulb, and leaves the heating coil at 30° C dry bulb, what is the change in enthalpy?

a. 52 kJ/kg
b. 42 kJ/kg
c. 15 kJ/kg
d. 20 kJ/kg
e. 10 kJ/kg

A

e. 10 kJ/kg

106
Q

Supply air duct leakage loss calculations include:

a. 20% leakage loss when the supply air duct is outside the conditioned space.
b. Losses from bare supply air ducts within the conditioned space.
c. 10% leakage loss when the supply air duct is outside the conditioned space.
d. 5% leakage loss when the supply air duct is outside the conditioned space.
e. 10% leakage loss when some of the supply air duct is outside the conditioned space and some inside.

A

c. 10% leakage loss when the supply air duct is outside the conditioned space.

107
Q

Which of the following is not found on the low side of an ammonia absorption refrigeration system?

a. Evaporator
b. Generator
c. Absorber
d. Cooling water
e. Low pressure ammonia vapor

A

b. Generator

108
Q

The concentration of Lithium Bromide in an absorption refrigerating system will change during which of the following steps?

a. Going through the expansion valve
b. Going through the suction valve
c. Cooling through the heat exchanger
d. Absorbing water vapor in the absorber
e. Going through the discharge valve

A

d. Absorbing water vapor in the absorber

109
Q

If a compressor fails to start but the motor is running which of the following could be a cause?

a. The control circuit is open
b. The compressor is seized
c. The coupling is sheared or broken
d. The motor is burned out
e. The starter is defective.

A

c. The coupling is sheared or broken

110
Q

An evaporator that contains only a small amount of liquid refrigerant at any time is what type of evaporator?

a. Dry evaporator
b. Flooded evaporator
c. A multi coil evaporator
d. All of the above
e. None of the above

A

a. Dry evaporator

111
Q

What are the three different kinds of pressure developed by a fan?

a. Static pressure, head pressure, suction pressure.
b. Velocity pressure, head pressure, suction pressure.
c. Static pressure, velocity pressure, total pressure.
d. Head pressure, suction pressure, total pressure.
e. Static pressure, head pressure, total pressure.

A

c. Static pressure, velocity pressure, total pressure.

112
Q

The volume of standard air is _____ m3/kg of dry air.

a. 0.533
b. 0.633
c. 0.733
d. 0.833
e. 0.933

A

d. 0.833

113
Q

A hot water system which circulates water through the pipes with a pump is known as a:

a. Circulating system
b. Forced system
c. Pumped system
d. Gravity system
e. Return system.

A

b. Forced system

114
Q

Effective temperature is defined as a measure of comfort that involves:

a. The effects of relative humidity.
b. The effects of air movement.
c. The effects of dry bulb temperature.
d. The effects of wet bulb temperature.
e. All of the above

A

e. All of the above

115
Q

To obtain full rated capacity of water coils what should be done?

a. Connect the water supply for counter flow.
b. Connect the water supply for parallel flow.
c. Decrease the number of fins per unit length of coil.
d. Connect the coils with a staggered tube design.
e. Increase face velocity

A

a. Connect the water supply for counter flow.

116
Q

Flat-finned surface type coils are normally used for:

a. Steam heating purposes.
b. Water heating purposes.
c. High temperature application.
d. Low temperature application where ice may form.
e. Greater turbulence of air at the fin surface.

A

d. Low temperature application where ice may form.

117
Q

The purpose of the flow switch or sail switch used with hot water coils is to:

a. Stop the fan and close the outside air dampers if the low limit temperature controller malfunctions or the heat source fails.
b. Open the outside air dampers wide when the outside air temperature rises.
c. Increase the heat source temperature if the outside air temperature decreases.
d. Close the outside air dampers and stop the fan if the flow of water is interrupted due to pump failure or closing of the hand valves.
e. Increase the hot water flow through the coil if the outside air temperature is too low

A

d. Close the outside air dampers and stop the fan if the flow of water is interrupted due to pump failure or closing of the hand valves.

118
Q

The packless radiator valve has a bronze diaphragm that completely seals off the valve body, this to prevent:

a. Air to enter into the radiator
b. Condensate collection on the valve body
c. Air leaking out around the valve stem
d. Steam leaking out around the valve stem
e. Steam pressure become excessive.

A

d. Steam leaking out around the valve stem

119
Q

This type of system works well in smaller buildings with multi-zone layouts. It provides good control of room temperature on a year round basis but is limited by the number of zones and the space needed for the supply ducts.

a. A low velocity terminal reheat system
b. A high velocity terminal reheat system
c. A multi-zone system
d. A dual duct system
e. A roof top unit.

A

c. A multi-zone system

120
Q

Which of the following is not an installation recommendation for steam traps?

a. Base steam trap selection on the pressure difference across the trap and a minimum capacity corresponding to three times the coil condensate rate.
b. Locate the steam trap so that its outlet is at least 30 cm above the coil return connection.
c. Trap each coil separately.
d. Drip the steam supply main through a steam trap into the return condensate main.
e. Install a strainer near the inlet of each trap

A

b. Locate the steam trap so that its outlet is at least 30 cm above the coil return connection.

121
Q

Temperature control by face and bypass dampers:

a. Closes the bypass damper and opens the face damper to force air across the coil
b. Closes the bypass damper and opens the face damper to force air around the coil
c. Opens the bypass damper and closes the face damper to force air across the coil
d. Increases air, flow through the bypass to increase air temperature
e. Restricts air, flow across the coil to increase air temperature

A

a. Closes the bypass damper and opens the face damper to force air across the coil

122
Q

Which law describes the existence of moisture in the air in vapor or evaporated state?

a. Newton’s laws of gravity.
b. 1st Law of Thermodynamics.
c. Dalton’s Law of Partial Pressures.
d. 2nd Law of Thermodynamics.
e. Boyle’s Ideal Gas Law

A

c. Dalton’s Law of Partial Pressures.

123
Q

Thermal conductance (C) may be defined as the:

a. Quantity of heat flow in unit time (Q or W)
b. Thermal transmission through a unit area of homogeneous material (W/m°C)
c. Thermal transmission through a unit area of a particular body with defined surfaces (W/m2°C)
d. Thermal transmission through a unit area of a particular body where the difference between temperatures on either side of the body is unity (W/m2°C)
e. Reciprocal of thermal conductance (m°C/W).

A

c. Thermal transmission through a unit area of a particular body with defined surfaces (W/m2°C)

124
Q

For which system/s is the central fan usually provided with variable inlet vanes for output adjustment to maintain a set pressure in the supply air duct?

  1. Variable air volume system
  2. Fan coil unit with make up air system
  3. Hydronic heat pump system
  4. Dual duct system
  5. Constant air volume system.

a. 1
b. 4
c. 5
d. 3, 4, 5
e. 2, 3, 4.

A

a. 1

125
Q

The run around coil heat recovery system uses a _____ coil in the inlet air duct and a _____ coil in the exhaust air duct.

a. Preconditioning, Recovery
b. Heating, cooling
c. Cooling, heating
d. Recovery, conditioning
e. Heating, recovery.

A

a. Preconditioning, Recovery

126
Q

Air louvers are:

a. Often used for mixing boxes.
b. Always used for fire and smoke dampers.
c. Suited for two position damper operation.
d. Used in fresh air intake openings to minimize the amount of water and snow entering the air handling system.
e. Used as relief dampers

A

d. Used in fresh air intake openings to minimize the amount of water and snow entering the air handling system.

127
Q

An eye made by using a Crosby clip will have a strength factor of:

a. 80%.
b. 50%.
c. 95%.
d. 75%.
e. 90%

A

a. 80%.

128
Q

The point of a properly ground drill bit should be:

a. 35°.
b. 78°.
c. 112°.
d. 118°.
e. 121°

A

d. 118°.

129
Q

A ball peen hammer is sometimes referred to as a:

a. Carpenter’s hammer.
b. Machinist’s hammer.
c. Mechanic’s hammer.
d. Millwright’s hammer.
e. Spherical mallet

A

b. Machinist’s hammer.

130
Q

The knot that forms a loop that will not slip or jam is the:

a. Square or reef knot
b. Figure eight
c. Clove hitch
d. Sheet bend
e. Bowline.

A

e. Bowline.

131
Q

For hoisting the most common method of getting a reasonable idea of, an objects _____ is by estimating it.

a. Size.
b. Shape.
c. Density.
d. Mass.
e. Specific gravity

A

d. Mass.

132
Q

A hot oil system uses a _____ fluid in place of steam or water, to conduct heat from a central source to other vessels and heating coils in a plant.

a. Refrigerant.
b. Cooling.
c. Heating.
d. Condensing.
e. Thermal

A

e. Thermal

133
Q

Relative humidity:

a. Increases when the air temperature is raised without the addition of moisture to the air.
b. Decreases when the air temperature is lowered without the addition of moisture to the air.
c. Decreases when the air temperature is raised without the addition of moisture to the air.
d. Remains the same when the air temperature is lowered.
e. Remains the same when the air temperature is raised.

A

c. Decreases when the air temperature is raised without the addition of moisture to the air.

134
Q

Laying up a boiler means:

a. Raising the boiler.
b. Preparing the boiler for a period of storage.
c. Setting the boiler on its foundation.
d. Taking the boiler down for an annual overhaul.
e. Preparing a boiler for start up

A

b. Preparing the boiler for a period of storage

135
Q

Dehumidification occurs in an air washer when which of the following occurs?

a. If the level in the bottom tank drops lower than the minimum level.
b. If water temperature is heated above the dry bulb temperature.
c. If spray water is cooled to a temperature below the dew point.
d. Heating of the spray water.
e. None of the above.

A

c. If spray water is cooled to a temperature below the dew point.

136
Q

In a reformer:

a. Naphtha is changed to increase its octane rating.
b. H2S and nitrogen are removed from and at lower temperature and pressure in order to ‘crack’ the product
c. Receives gas oils from the crude unit and lower temperature and pressure distills the product.
d. Receives gas oils from the crude unit and at higher temperature and lower pressure distills the product.
e. Asphalt is produced

A

a. Naphtha is changed to increase its octane rating.

137
Q

A diesel hydrotreater in an oil refinery:

a. Removes sulphur and nitrogen compounds before the naphtha goes to the platformer.
b. Causes the heavy hydrocarbons to be transformed into lighter hydrocarbons.
c. Only removes water from the diesel fuel.
d. Removes sulphur and nitrogen compounds from the diesel fuel before it goes to storage.
e. Removes water from the crude oil.

A

d. Removes sulphur and nitrogen compounds from the diesel fuel before it goes to storage.

138
Q

In a fin-coil heat exchanger, the primary source of heat for the exchanger is:

a. Steam or hot water
b. Gas
c. Oil
d. Solar
e. Radiant.

A

a. Steam or hot water

139
Q

It is important to drain a hot oil heater prior to attempting a radiographic inspection, because:

a. Oil and coke appear similar on the x-ray picture.
b. Oil and coke give a similar sound when the tube is hammered.
c. X-rays passing through the oil might cause an explosion.
d. Drained tubes are cleaner for the radiologist to work with.
e. It is safer

A

a. Oil and coke appear similar on the x-ray picture.

140
Q

Suitable gasket material for use in the flange connections of a hot oil system is:

a. Asbestos.
b. Rubber.
c. Metallic.
d. Cork.
e. Leather.

A

c. Metallic.

141
Q

In order not to be harmful to the metals used in hot oil systems the thermal fluid must:

a. Be kept at a low temperature.
b. Have a neutral pH value.
c. Be non-corrosive.
d. Be diluted with glycol.
e. Be mixed with kerosene

A

c. Be non-corrosive.

142
Q

A temperature and pressure which could be expected at the exit of a fired hot oil heater is between:

a. 120°C and 60 kPa.
b. 235 to 290°C and 450 kPa.
c. 60°C and 120 kPa.
d. 450 to 500°C and 255 kPa.
e. 150 to 300°C and 400 kPa.

A

b. 235 to 290°C and 450 kPa.

143
Q

The predominant constituent of natural gas, is often occupying up to 95% by volume is:

a. Propane.
b. Methane.
c. Ethane.
d. Butane.
e. Hydrogen sulphid

A

b. Methane.

144
Q

In the Kraft process, the chipped wood is further processed in one of the following:

a. Recovery boiler.
b. Bleacher.
c. Press.
d. Hogger.
e. Digester.

A

e. Digester.

145
Q

Firetubes are cleaned to remove deposits of:

a. Scale
b. Salt
c. Soot
d. Corrosion
e. Algae.

A

c. Soot

146
Q

The most typical fired heater model is the:

a. Down-draft.
b. Dual-draft.
c. Up-draft.
d. Balanced-draft.
e. Induced-draft.

A

c. Up-draft.

147
Q

Chemical cleaning of smaller boilers is not usually done because:

a. Of the small surface area which the chemical contacts.
b. Of the thin metal of which they are manufactured.
c. They do not have adequate support for the high density of the chemicals.
d. It is impossible to get the chemical circulating adequately.
e. The cost to do so is not warranted or justified

A

e. The cost to do so is not warranted or justified

148
Q

A relatively new and safer chemical used in boiler cleaning and treatment is:

a. Chelates.
b. Trisodium phosphate.
c. Sodium hydroxide.
d. Caustic soda.
e. Hydrazine.

A

a. Chelates.

FINAL PWEN ABSA PRACTICE 4 (1 decks)

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