Air Flow & Duct Work

Question 1

The conditions in the atmosphere refer to ______?

Answer 1

Weather

Question 2

The density of air is:

Answer 2

How much air weighs per cubic foot

Question 3

The specific volume of air is:

Answer 3

How much volume 1 pound of air occupies

Question 4

The relative humidity of air is:

Answer 4

The percentage of moisture air is holding as opposed to the amount it could hold if it were saturated

Question 5

As air is heated it:

Answer 5

Expands

Question 6

The air pressure in a sealed balloon is:

Answer 6

Static pressure

Question 7

A blower connected to a length of duct creates:

Answer 7

static pressure, which is then converted to velocity pressure

Question 8

Velocity pressure is determined by:

Answer 8

Subtracting static pressure from total pressure

Question 9

An inclined manometer is basically a:

Answer 9

U-tube manometer tilted at a steep angle

Question 10

An inclined manometer is basically a:

Answer 10

U-tube manometer tilted at a steep angle

Question 11

The static pressure of a duct is 1.76”, and the total pressure is 2”. What is the velocity pressure?

(Velocity Pressure = Total pressure - Static Pressure)

Answer 11

.24”

Question 12

The static pressure of a duct is 1.76”, and the total pressure is 2”. What is the velocity pressure?

(Velocity Pressure = Total pressure - Static Pressure)

Answer 12

.24”

Question 13

A pitot tube can directly measure:

Answer 13

Total and static pressures

Question 14

How many holes must be made in a round duct in order to take a series of traverse readings?

Answer 14

Two

Question 15

How many holes must be made in a round duct in order to take a series of traverse readings?

Answer 15

Two

Question 16

A thermo-anemometer measures:

Answer 16

fpm directly

Question 17

Dehumidification occurs when an air conditioning coil:

Answer 17

operates at or below the dew point of the air moving across it

Question 18

Dehumidification occurs when an air conditioning coil:

Answer 18

operates at or below the dew point of the air moving across it

Question 19

When testing a duct system to determine its leakage rate, why is a special test stand necessary?

Answer 19

It contains a calibrated orifice and matching flow chart for that orifice.

It is manufactured to accepted testing standards.

Test results can be traced to the specific test stand used for the test if there are concerns about accuracy.

Question 20

When the dry bulb temperature increases, the relativity humidity of air:

Answer 20

Decreases

Question 21

When the dry bulb temperature increases, the wet bulb temperature:

Answer 21

Increases

Question 22

When the dry bulb temperature increases, the dew point temperature:

Answer 22

Remains the same

Question 23

When the dry bulb temperature increases, the specific humidity:

Answer 23

Remains the same

Question 24

When the dry bulb temperature increases, the specific volume of the air:

Answer 24

Increases

Question 25

When the dry bulb temperature increases, the density of air:

Answer 25

Decreases

Question 26

There are _________ grains of water vapor per pound of water.

Answer 26

7,000

Question 27

There are _________ pounds per cubic foot of air.

Answer 27

.075

Question 28

The cfm per ton rate for normal comfort cooling is approximately:

Answer 28

400 cfm/ton

Question 29

Cooling air raises its:

Answer 29

Relative humidity

Question 30

Air with a dry bulb temperature of 60 degrees and a wet bulb temperature of 60 degrees has a relative humidity of:

Answer 30

100%

Question 31

Air with a dry bulb temperature of 60 degrees and a wet bulb temperature of 60 degrees has a dew point temperature of:

Answer 31

60 degrees

Question 32

Decreasing the cfm over an evaporator will _______ the moisture removal from the air.

Answer 32

increase

Question 33

A rotating velometer measures:

Answer 33

feet

Question 34

Return air grilles are not to be installed in:

Answer 34

Bathrooms or kitchens

Question 35

The proper amount of air in cfm for each room is determined by:

Answer 35

A detailed room-by-room heat load calculation

Question 36

On residential duct installations the accepted method of attaching duct sections to each other is:

Answer 36

Using the slip and drive method

Question 37

Which of the following is not an acceptable location for a thermostat?

Answer 37

5" off the floor on an outside wall

Question 38

What is the difference between accuracy and precision when applied to instruments?

Answer 38

Accuracy is a measure of how close the measurement is to being correct. Precision is the measure of how small a value the instrument can detect.

Question 39

The range of an instrument is the:

Answer 39

difference between the lowest and highest readings the instrument can measure

Question 40

difference between the lowest and highest readings the instrument can measure

Answer 40

4,000 cfm

Question 41

A 32" by 32" square duct is to be changed to a height of 28" so it will fit around an obstruction in a boiler room. How wide must the duct be in order to maintain the same area? Round the number off to the nearest whole number of inches.

Answer 41

37"

Question 42

(T/F) The greater the velocity, the more resistance there is to a change in direction.

Answer 42

T

Question 43

(T/F) If the duct area decreases, the velocity increases.

Answer 43

T

Question 44

(T/F) When a fitting creates turbulence, the turbulence continues for several feet down the duct.

Answer 44

T

Question 45

A 24" by 8" rectangular duct has an aspect ratio of:

Answer 45

3:1

Question 46

The most efficient method of air balancing a duct system is the:

Answer 46

proportional method

Question 47

Which of the following types of turning vanes produce the least dynamic system loss?

Answer 47

Single wall vanes

Question 48

Which equations is used to determine the actual operating capacity of a system?

Answer 48

Btuh = 4.5 × cfm × the difference in enthalpy between the return and supply air

Question 49

What is known as the “silent killer”?

Answer 49

Carbon monoxide

Question 50

___________ ventilation is a control strategy used to maintain a high oxygen content in buildings where a healthy environment is of particular concern.

Answer 50

Demand

Question 51

The most economical means of measuring the amount of oxygen deprivation in an occupied space is through the use of a:

Answer 51

carbon dioxide sensor

Question 52

What is the natural result of combustion?

Answer 52

Carbon dioxide, Water vapor, Carbon monoxide

Question 53

The most serious result of incomplete combustion in any fuel-burning heating device is:

Answer 53

Carbon monoxide

Question 54

Carbon monoxide poisoning is often mistaken for:

Answer 54

The flu with a headache

Question 55

Carbon monoxide is measured in:

Answer 55

PPM

Question 56

Outdoor air intake dampers should be located away from:

Answer 56

Busy ground level intersections Loading docks Sewer vents

Question 57

Infiltration is air that:

Answer 57

enters a space without filtration or control

Question 58

Offgassing is:

Answer 58

The release of volatile compounds from products and construction materials Usually harmful compounds and chemicals, which slowly enter living spaces over time Chemicals released into the air especially as the host material is heated

Question 59

In the science of indoor air quality VOC stands for:

Answer 59

Volatile Organic Compounds

Question 60

Which of the following are common symptoms of carbon monoxide poisoning?

Answer 60

Headache and nausea Fatigue and dizziness Shortness of breath

Question 61

Nitrogen dioxide is a toxin resulting from:

Answer 61

Both the process of combustion and rapid oxidation

Question 62

(T/F) The quality of air indoors can often be worse than that of the outdoors.

Answer 62

True

Question 63

Mitigation means to:

Answer 63

alleviate

Question 64

Solid particles suspended in air are measured in:

Answer 64

Parts per million

Question 65

Which of the following organizations has legal oversight over air quality in the United States?

Answer 65

EPA

Question 66

The higher the velocity of the air through a fiber filter, the:

Answer 66

Less effective the filtration

Question 67

At what level of indoor air carbon monoxide do most fire departments require emergency personnel to wear self-contained breathing apparatus (SCBA)?

Answer 67

50 ppm

Question 68

The function of an ERV is to:

Answer 68

Exchange heat between exhaust and intake air

Question 69

ASHRAE standard 55-1992 specifies the conditions likely to be thermally acceptable to _______ of adult occupants of a conditioned space.

Answer 69

75%

Question 70

Indoor air quality is legally the responsibility of:

Answer 70

The building owner The business leasing the building Those operating and maintaining the building

Question 71

Clean rooms are classified according to:

Answer 71

The particle count per cubic foot of air

Question 72

HEPA stands for:

Answer 72

High Efficiency Particulate Air filter

Question 73

The internal static pressure in a building should be approximately:

Answer 73

.05" higher than the outside air pressure

Question 74

Activated charcoal is often satisfactory for the removal of:

Answer 74

Gas-phase toxic or odorous pollutants

Question 75

A __________ biological safety cabinet is a gastight negative pressure containment system that provides a physical barrier between the agent and the worker.

Answer 75

class 3

Question 76

Is refrigerant oil that has gone through a compressor burn-out classified as a toxic waste?

Answer 76

Yes, if the oil contains a substance classified by the EPA as a toxic waste.

Question 77

Three common methods used to mitigate poor indoor air quality are:

Answer 77

Filtration, ventilation, and exhaust

Question 78

A micron is:

Answer 78

One 25,400th of an inch

Question 79

Bacteria, molds, pollen, and viruses are types of:

Answer 79

Biological contaminants

Question 80

According to the World Health Organization approximately what percentage of buildings suffer from SBS (Sick Building Syndrome)?

Answer 80

30%

Question 81

A key factor in solving indoor air quality problems is to:

Answer 81

Locate and isolate the source of the pollution

Question 82

Which of the following would be the first step in the process of investigating an indoor air quality problem at a building?

Answer 82

Defining the perceived problem

Question 83

Physical stressors are those factors that:

Answer 83

Can be sensed, felt, seen, or heard

Question 84

Sick Building Syndrome is highly suspected when:

Answer 84

20% or more of the building occupants complain with physical symptoms within a 2-week period. A high degree of occupants call in sick with symptoms of headaches, fatigue, dizziness, coughing, nausea, and eye or throat irritations. A high degree of occupants find that their symptoms are alleviated by leaving the building.

Question 85

During an initial pre-investigatory building walk-through, which of the following measurements may be taken?

Answer 85

Carbon dioxide, temperature, and relative humidity readings

Question 86

What gas originates from manmade materials within a building?

Answer 86

Formaldehyde

Question 87

What can affect the intensity of a person’s reaction to an irritant in the air?

Answer 87

Temperature and humidity

Question 88

A fairly common but not regularly recognized source of poor indoor air quality and increased dust and residue in homes is:

Answer 88

The use of candles

Question 89

What substances has been directly attributed to as many as 20,000 cases of lung cancer in the United States?

Answer 89

Radon gas

Question 90

Concentrations of radon gas is measured in:

Answer 90

picocuries

Question 91

Particulates are categorized in terms of:

Answer 91

Size and source

Question 92

Excessively high concentrations of carbon dioxide in indoor air is usually an indication of:

Answer 92

A lack of ventilation air

Question 93

Which of the following IAQ problems was first discovered to have its source in HVAC cooling towers?

Answer 93

Legionnella

Question 94

Organic compounds are:

Answer 94

Compounds that contain carbon

Question 95

A compound is a:

Answer 95

material made up of two or more elements electrically bound to one another

Question 96

TLV stands for:

Answer 96

Threshold limit value

Question 97

The average urban outdoor air concentration of carbon dioxide has been determined to be:

Answer 97

40 ppm