Power Engineering 4th Class - Part B -
10 Unit Review Questions With
Correct Answers 2026 Update
Wet-bulb temperature is:
Select one:
a. Always less than the dry-bulb temperature
b. The product of the dry-bulb temperature times the relative humidity.
c. The dew point temperature
d. The temperature indicated by a thermometer whose bulb covered by a
water-wetted wick, and exposed to a rapidly moving stream of air - Ans--The
temperature indicated by a thermometer whose bulb covered by a water-
wetted wick, and exposed to a rapidly moving stream of air
Which of the following steam traps are recommended for use with steam
coils operating at low or medium steam pressure?
Select one:
a. Impulse trap
b. Thermostatic trap
c. Float and thermostatic trap
d. Inverted bucket trap - Ans--Float and thermostatic trap
Air ducts of large dimensions must be diagonally creased
Select one:
a. To increase air velocity
b. To decrease air friction in the duct work
c. To allow expansion and contraction
d. To provide stiffness - Ans--To provide stiffness
Modulating control valves:
Select one:
a. Should be over-sized to prevent steam coil freeze-up.
b. Can successfully control steam coils, as long as the air entering the coil is
at or above 1.5°C .
, c. Are mainly used for steam coils when the entering air temperature is below
1.5°C.
d. Are used for steam coils where the condensate must be lifted to an
overhead condensate return line.
e. Are never used to control steam coils, regardless of inlet air temperature. -
Ans--Can successfully control steam coils, as long as the air entering the coil
is at or above 1.5°C
An air filter capable of removing particles as small as 0.3 micron in diameter
with 99% efficiency is a
Select one:
a. an odour absorber.
b. a charged-media aircleaner.
c. a HEPA filter.
d. a viscous impingement filter - Ans--a HEPA filter.
Steam grid humidifiers used in HVAC systems work by injecting steam into
Select one:
a. the supply air stream
b. the rooms to be humidified
c. the spray water of an air washer
d. the make-up air stream - Ans--the supply air stream
The dew point is the:
Select one:
a. Temperature at which water will start to evaporate
b. Pressure below which water vapour will start to condense out of the air
c. Temperature below which water vapour will start to condense out of the air
d. Temperature at which water vapour will start to be absorbed into the air -
Ans--Temperature below which water vapour will start to condense out of
the air
The purpose of humidification is to:
Select one:
a. Remove moisture from the air during the heating season
b. Remove moisture from the air during the cooling season
c. Add moisture to the air during the cooling season
10 Unit Review Questions With
Correct Answers 2026 Update
Wet-bulb temperature is:
Select one:
a. Always less than the dry-bulb temperature
b. The product of the dry-bulb temperature times the relative humidity.
c. The dew point temperature
d. The temperature indicated by a thermometer whose bulb covered by a
water-wetted wick, and exposed to a rapidly moving stream of air - Ans--The
temperature indicated by a thermometer whose bulb covered by a water-
wetted wick, and exposed to a rapidly moving stream of air
Which of the following steam traps are recommended for use with steam
coils operating at low or medium steam pressure?
Select one:
a. Impulse trap
b. Thermostatic trap
c. Float and thermostatic trap
d. Inverted bucket trap - Ans--Float and thermostatic trap
Air ducts of large dimensions must be diagonally creased
Select one:
a. To increase air velocity
b. To decrease air friction in the duct work
c. To allow expansion and contraction
d. To provide stiffness - Ans--To provide stiffness
Modulating control valves:
Select one:
a. Should be over-sized to prevent steam coil freeze-up.
b. Can successfully control steam coils, as long as the air entering the coil is
at or above 1.5°C .
, c. Are mainly used for steam coils when the entering air temperature is below
1.5°C.
d. Are used for steam coils where the condensate must be lifted to an
overhead condensate return line.
e. Are never used to control steam coils, regardless of inlet air temperature. -
Ans--Can successfully control steam coils, as long as the air entering the coil
is at or above 1.5°C
An air filter capable of removing particles as small as 0.3 micron in diameter
with 99% efficiency is a
Select one:
a. an odour absorber.
b. a charged-media aircleaner.
c. a HEPA filter.
d. a viscous impingement filter - Ans--a HEPA filter.
Steam grid humidifiers used in HVAC systems work by injecting steam into
Select one:
a. the supply air stream
b. the rooms to be humidified
c. the spray water of an air washer
d. the make-up air stream - Ans--the supply air stream
The dew point is the:
Select one:
a. Temperature at which water will start to evaporate
b. Pressure below which water vapour will start to condense out of the air
c. Temperature below which water vapour will start to condense out of the air
d. Temperature at which water vapour will start to be absorbed into the air -
Ans--Temperature below which water vapour will start to condense out of
the air
The purpose of humidification is to:
Select one:
a. Remove moisture from the air during the heating season
b. Remove moisture from the air during the cooling season
c. Add moisture to the air during the cooling season
