4th Class Power Engineering Practice Questions competency test 80 to 100

Question 80

The most suitable material for a kitchen exhaust duct is: C
A) rubber-lined aluminium
B) aluminium sheet metal
C) black steel sheet metal
D) fibreglass
E) cement asbestos

Question 81

Ducts of large dimensions must be diagonally creased in order to: A
A) provide stiffness.
B) allow gradual duct size change.
C) decrease duct weight.
D) increase air velocity.
E) decrease air friction in the duct work.
Question 82

To reduce the transmission of noise and vibration from the fan to the
duct: D
A) flexible connections must be provided at fan discharge and suction
openings.
B) the fan casing must be constructed of fibreglass.
C) the duct and the fan must be suspended.
D) the duct and the fan must be bolted together tightly.
E) only scroll-case fans may be used.


Question 83

In an air conditioning duct system, short radius elbows should be provided
with: A
A) turning vanes.
B) mitre elbows.
C) positive lock dampers.
D) flexible connections.
E) joint stiffeners.

Question 84

Seepage into return air ducts furred within the conditioned space will: B
A) increase the amount of air needed to supply the conditioned space.
B) increase the load on the air system in terms of volume of air.
C) increase the static pressure at the fan discharge.
D) noticeably increase the system noise factor.
E) deteriorate the duct's insulation.


Question 85

In an air conditioning system with supply air ducts outside the conditioned
space, how must leakage be included in loss calculations: A
A) It must be added to the calculated room sensible heat load.
B) It need not be considered in the loss calculation.
C) It must be subtracted from the return air duct leakage.
D) It must be added to the return air duct leakage.
E) It must be added to the calculated room specific latent humidity load.


Question 86

A supply air duct has a total length of 100 m, with 70 m in the conditioned
space. What is the percentage of air leakage that must be counted in the
calculation of heat loss for this system: B
A) 30%
B) 10%
C) 7%
D) 3%
E) 2.1%


Question 87

Which of the following statements about leakage from air conditioning ducts
is TRUE: D?
A) The effects of air leakage in supply air ducts are the same as those in
return ducts.
B) Leakage inspection can only be done after the duct is covered in
insulation.
C) Losses from bare supply air ducts within the conditioned space have a
substantial impact on loss calculations.
D) Losses due to air leakage from furred supply air ducts within the
conditioned space can only be evaluated on the basis of judgement.E) Air
leakage varies for
40% to 45%.


Question 88

Semi-rigid fibrous glass blankets are attached to the inside of air
conditioning distribution ducts primarily to: C
A) provide thermal insulation.
B) act as a fire retardant.
C) attenuate airborne noises.
D) stop air leakage in the seams of the duct work.
E) restrict the spread of smoke in event of fire.


Question 89

The factor used to determine the spacing of fasteners and edge treatment of
air conditioning duct liners is the: B
A) fire rating of the duct.
B) velocity classification of the duct.
C) liner materials to be used.
D) type of adhesive to be used.
E) type of fastener to be used.


Question 90

Manual air conditioning duct dampers are used primarily for: C
A) starting and stopping the flow of air.B
B) balancing the airflow.
C) diverting the airflow.
D) modulating the airflow.
E) by-passing the air flow.


Question 91

A mixing box in an air conditioning duct system is an example of a
___________ damper.B
A) manual
B) modulating
C) relief
D) two position
E) fire


Question 92

In air conditioning duct systems, the device that functions similarly to a
check valve is the: D
A) manual damper.
B) modulating damper.
C) two-position damper.
D) relief damper.
E) louver.


Question 93

In air conditioning duct systems, relief dampers are normally used on: D
A) supply air ducts
B) branch air ducts
C) mixing boxes
D) exhaust air ducts
E) return air ducts


Question 94

In air conditioning duct systems, opposed blade dampers are used when: B
A) air mixing is required.
B) air volume regulating is required.
C) air diverting is required.
D) air exhaust is required.
E) air pressure in the duct is too high.


Question 95

The National Building Code specifies that when passing from one fire zone to
another fire zone, fire dampers are to be installed on a building's: A
A) supply and return ducts.
B) return ducts only.
C) supply ducts only.
D) kitchen exhaust ducts only.
E) outside air intake ducts only.


Question 96 Value: 1 Path:

Stationary louvers install in the fresh air intake of an air handling system
serve the functions of: A
1. preventing entry of insects and birds.
2. minimizing snow and water entry.
3. providing pleasing aesthetic requirements.
4. providing tight shut-off in event of fire.
A) 1, 2 and 3 ONLY
B) 1, 2 and 4 ONLY
C) 1, 3 and 4 ONLY
D) 2, 3, and 4 ONLY
E) 1, 2, 3, and 4


Question 97

The "occupied zone" of an air conditioned space is defined as the space
which is:E
A) occupied by occupants.
B) above 2 m from the floor and 1 m from the walls.
C) filled with conditioned air.
D) within 2 m from the floor and 2 m from the walls.
E) within 2 m from the floor and 1 m from the walls.


Question 98

The process in which conditioned air is distributed into the controlled
space by rapid mixing of supply air and room air is known as:E
A) induction
B) entrainment
C) aspiration
D) injection
E) diffusion


Question 99

In an air conditioning system, the difference between a register and a grill
is that: E
A) a register is installed on the supply air outlet but a grill is installed
on the return air outlet.
B) a register is installed on the wall but a grill is installed on the
ceiling.
C) a register can not direct air flow but a grill can.
D) a register is installed on the return air inlet and a grill is installed
on the supply air outlet.
E) a register can regulate air flow but a grill cannot.


Question 100

Which of the following is NOT a function of terminal air distribution
devices?D
A) Distribute the air to the spaces.
B) Provide uniform space temperatures.
C) Control or counteract the effects of conduction, convection and
radiation.
D) Create local pockets of still air.
E) Provide adequate air motion.