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Term 3 - Ductwork > RACT Assignment > Flashcards

RACT Assignment Flashcards

1
Q

Air that enters a structure from leaks around windows and doors is best described as

A

infiltration air

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2
Q

An example of a natural-draft system is:

a) hot water baseboard heating
b) radiant heating
c) reverse cycle (heat pump) refrigeration
d) central air

A

a

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3
Q

All of the following are desirable characteristics of a forced-air system except:

a) air movement not felt by occupants of space
b) air noise not noticed by occupants
c) td between rooms are minimal
d) equipment cycling is noticeable

A

d

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4
Q

The pressure in a duct system is measured in:

A

inwc

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5
Q

At standard conditions, atmospheric pressure can support a column of water that is approximately how high?

a) 3.4ft
b) 8.5ft
c) 17ft
d) 34ft

A

d

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6
Q

The pressure that represents force pushing outward against the walls of the duct system is referred to as the?

a) viscosity pressure
b) static pressure
c) velocity pressure
d) total pressure

A

b

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7
Q

Which of the following is an accurate expression that relates the three duct system pressures?

A. Total Pressure = Viscosity Pressure - Static Pressure
B. Velocity Pressure = Total Pressure - Static Pressure
C. Static Pressure - Velocity Pressure = Viscosity Pressure
D. Total Pressure = Velocity Pressure/ Static Pressure

A

b

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8
Q

The instrument that is used to measure duct system pressures is the

A. velometer
B. speedometer
C. anemometer
D. manometer

A

d

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9
Q

An anemometer is used to directly measure the

A. volume of air flowing through a duct
B. speed of air flowing through a duct
C. density of air flowing through a duct
D. moisture content of air flowing through a duct

A

b

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10
Q

How much air is flowing through a 10 in. x 12 in. duct if the air is traveling at a speed of 700 feet per minute

A. 122 cfm
B. 351 cfm
C. 583 cfm
D. 827 cfm

A

c

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11
Q

Which of the following sets of instruments are most similar to each other?

A. Anemometer and velometer
B. Potentiometer and anemometer
C. Manometer and velometer
D. Potentiometer and manometer

A

a

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12
Q

Squirrel-cage-type blowers are used in conjunction with duct system because they

A. are less expensive than propeller-type fans for this application
B. create less of a pressure differential between their inlet and outlet
C. are able to overcome the pressures that are present in the duct system
D. are easier to mount in duct systems than propeller type fans

A

c

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13
Q

Which of the following is true regarding the amperage draw of a blower motor being used to move air through a duct system?

A. Motor amperage will go up if the blowerā€™s inlet is blocked
B. Motor amperage will go up if the blowerā€™s outlet is blocked
C. Motor amperage will go down if the door on the blower compartment is removed
D. Motor amperage will go up if the door on the blower compartment is removed

A

d

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14
Q

The type of a blower assembly that utilizes both motor shaft and blower shaft bearings is the

A. combination-drive blower assembly
B. direct-drive blower assembly
C. belt-drive blower assembly
D. isolation-drive blower assembly

A

c

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15
Q

The type of blower assembly that utilizes only motor shaft bearings is the

A. combination-drive blower assembly
B. direct-drive blower assembly
C. belt-drive blower assembly
D. isolation-drive blower assembly

A

b

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16
Q

Which of the following blower assemblies is used in conjunction with changeable or adjustable pulleys that can vary the blower speed?

A. combination-drive blower assembly
B. direct-drive blower assembly
C. belt-drive blower assembly
D. isolation-drive blower assembly

A

c

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17
Q

Which of the following is false regarding a duct system that is oversized?

A. Increased fabrication costs
B. Increased installation costs
C. Increase noise levels
D. Decreased air velocity

A

c

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18
Q

Which of the following is a benefit of reducing plenum air distribution system?

A. The velocity of the air is maintained throughout the system
B. It is the least expensive of all duct system options
C. It requires only a minimal amount of rigid ductwork
D. The air pressures in the duct system vary greatly from inlet to outlet

A

A

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19
Q

Which of the following air distribution systems is commonly installed in a poured slab floor?

A. Plenum system
B. Extended plenum system
C. Reducing plenum system
D. Perimeter loop system

A

d

20
Q

Rectangular metal duct sections are commonly joined together with

A. duct type
B. slips and drives
C. mastic
D. self-tapping sheet metal screws

A

b

21
Q

Galvanized sheet metal is treated/coated with which substance to slow the corrosion process?

A. Zinc
B. Tin
C. Aluminum
D. Steel

A

A

22
Q

Sheet metal duct sections are often fabricated with cross breaks to

A. reduce air turbulence in the duct
B. prevent the duct from sweating
C. make the duct section more rigid
D. improve the appearance of duct

A

C

23
Q

Flexible duct

A. is desirable because it has a very low resistance to airflow
B. is ideally used for very short, direct duct runs
C. Is available in sizes up to 8 in. in diameter
D. is desirable because it is less likely to kink than rigid duct

A

B

24
Q

The branch duct is connected to the main trunk line with a

A. boot fitting
B. takeoff fitting
C. transition fitting
D. offset fitting

A

B

25
Q

A streamlined takeoff fitting is designed with

A. a throat that is larger than the runout duct it is connected to
B. a throat that is smaller than the runout duct it is connected to
C. a throat that is the same size as the runout duct it is connected to
D. a throat that is the same size as the main trunk line it is connected to

A

A

26
Q

Balancing dampers are ideally located

A. as close to the supply register location as possible
B. as far from the main supply trunk as possible
C. as close as possible to the main supply trunk
D. as close as possible to the air handler in the main supply duct

A

C

27
Q

Which of the following statements is accurate with regards to simple system zoning?

A. Zone dampers are manually operated based on space temperature
B. Zone dampers are manually operated based on space occupancy
C. Zone dampers are automatically operated based on space temperature
D. Zone dampers are automatically operated based on space occupancy

A

C

28
Q

If an air-conditioning system has three independent zones, how many space thermostats will the system have?

A. 1
B. 2
C. 3

A

C

29
Q

Which of the following are challenges that need to be addressed when a single speed blower motor is used on a zoned air-conditioning system?

A. Reduced airflow, increased noise, evaporator coil freeze ups
B. Increased airflow, reduced air velocity, high system operating pressures
C. Increased airflow, increased noise, evaporator coil freeze-ups
D. Reduced airflow, lower system operating pressures, condenser coil freeze-ups

A

A

30
Q

Ducts are insulated to

A. prevent duct sweating and increase the heat transfer rate between the air in and around the duct
B. encourage duct sweating and increase the heat transfer rate between the air in and around the duct
C. encourage duct sweating and decrease the heat transfer rate between the air in and around the duct
D. prevent duct sweating and decrease the heat transfer rate between the air in and around the duct

A

D

31
Q

Supply registers should be positioned and configured so that

A. the supply air is directed to the center of the room
B. cooling air is introduced to the occupied space via floor registers
C. the supply air is directed onto the walls of the room
D. heating air is introduced to the occupied space via ceiling registers

A

C

32
Q

Duct systems must be properly sized and designed to reduce and overcome the effects of

A. resistance to flow at the supply registers
B. friction within the duct system
C. resistance to flow at the return grilles
D. excessive airflow in the main supply trunk

A

B

33
Q

A technician is traversing a duct and obtains the following 8 velocity readings: 500 fpm, 400 fpm, 375 fpm, 625 fpm, 275 fpm, 360 fpm, 420, and 575 fpm. What is the velocity value that will be used for system calculations?

A. 350 fpm
B. 440 fpm
C. 530 fpm
D. 620 fpm

A

B

34
Q

If there seems to be reduced airflow at all supply register locations, which of the following is the most likely problem with the system?

A. One or more supply registers are closed
B. One or more balancing dampers are closed
C. The system air filter is dirty
D. A branch duct has come loose from the main trunk line

A

C

35
Q

If a gas-fired furnace is constantly tripping on a high limit safety control, which of the following is likely NOT a cause for this condition?

A. Dirty air filter
B. Improperly balanced air distribution system
C. Defective furnace blower motor
D. Duct lining has come loose from the main trunk line

A

B

36
Q

The propeller-type fan is most often used as a (n) ____________________

A. centrifugal blower
B. exhaust fan or a condenser fan
C. blower motor in a residential gas furnace
D. all of the above

A

B

37
Q

The two types of drive assemblies that are commonly used to turn fans and blowers are __________________________

A. screw drive and rotary drive
B. rotary drive and scroll drive
C. belt drive and direct drive
D. direct drive and rotary drive

A

C

38
Q

A (n) ___________________ is recommended on all installations to prevent noise transmission through the duct system.

A. electronically commutated motor (ECM)
B. vibration eliminator
C. fiberglass plenum
D. direct-drive blower assembly

A

B

39
Q

The return duct system distributes air to the terminal units, registers, grilles, or diffusers in the conditioned space.

True or False

A

False

40
Q

Plenum, extended plenum, reducing plenum, or perimeter loop are all types of _________________.

A. ventilation methods
B. duct materials
C. duct systems
D. air balancing methods

A

C

41
Q

A ________________________ is used to make a duct more rigid, which prevents it from swelling and making noises when the blower starts and stops

A. balancing damper
B. cross-break
C. takeoff fitting
D. vibration eliminator

A

B

42
Q

Flexible round duct comes in sizes up to about 24 inches in diameter and 25 feet of length to a box

True or False

A

True

43
Q

A branch duct should be fastened to the main trunk line with a __________________

A. flex connector
B. takeoff fitting
C. end cap
D. boot

A

B

44
Q

_________________ is a very thick, putty-like substance that is applied to the duct connections to help make the system airtight.

A. Foil tape
B. Double-sided tape
C. Duct insulation
D. Mastic

A

D

45
Q

Fasteners called ā€œSā€ cleats and drive cleats are used to connect round metal duct sections together

True or False

A

False

Term 3 - Ductwork (4 decks)

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