OB1

Question 1

Refrigeration is the process of ___ the air in a defined space

adding moisture to
cleaning
increasing the movement
lowering the temperature

Answer 1

D

Question 2

The temperature of a material decreases if the material ___ and nothing else happens that would have the opposite effect

condenses
contacts a cooler material
contacts a warmer material
freezes

Answer 2

B

Question 3

The two kinds of air conditioning are

comfort and process
commercial and industrial
heat transfer and change of state
temp. and humidity

Answer 3

A

Question 4

One of the physical states of matter is

atom
element
gas
molecule

Answer 4

C

Question 5

You can cause matter to change its physical state by

adding or removing heat
allowing it to age
chemically altering it
separating its atoms

Answer 5

A

Question 6

Thermal energy that is directly related to the temperature of a material is called ___ heat

change of state
latent
potential
sensible

Answer 6

D

Question 7

A temperature of 45 degrees is about the same as ___ Celsius

7
13
25
58

Answer 7

A

Question 8

Heat can be transferred from one place to another by the process of

change of state
conduction
diffusion
insulation

Answer 8

B

Question 9

The latent heat of vaporization of a substance is the amount of heat the substances absorbs as it

condenses
evaporates
freezes
melts

Answer 9

B

Question 10

A line containing the refrigerant breaks, what happens inside the system?

nothing
the liquid refrigerant boils
the pressure increases
the refrigerant gets warmer

Answer 10

B

Question 11

From the compressor, refrigerant flows to the

condenser
evaporator
metering device
reservoir

Answer 11

A

Question 12

What point is superheating?

1
2
3
4

Answer 12

A

Question 13

Compared to a dry expansion evaporator, a flooded evaporator of the same size

contains no vapor
is more efficient
leaks refrigerant
requires no metering device

Answer 13

B

Question 14

The purpose of a cooling medium is to

absorb excess refrigerant vapor
condense the water vapor in moist air
remove heat from compressed refrigerant vapor

Answer 14

C

Question 15

An automatic expansion valve is a metering device that maintains a constant pressure in the

compressor
condenser
evaporator
surge drum

Answer 15

C

Question 16

The properties of air that are important in psychrometric include

enthalpy
odor
oxygen content
velocity

Answer 16

A

Question 17

Wet bulb temp is usually lower than the dry bulb. if the difference is small the air is

cool
dry
humid
warm

Answer 17

C

Question 18

Air that is saturated is air that is at the

desired temperature
dewpoint temperature
lowest possible relative humidity
optimum oxygen content

Answer 18

B

Question 19

Relative humidity changes if the ___ changes but the specific humidity does not

barometric pressure
dewpoint temperature
dry bulb temperature
weight of dry air

Answer 19

C

Question 20

To calculate the enthalpy of a sample of air, you must include

latent heat of the air
latent heat of the water vapor
relative humidity of the air
specific humidity of the air

Answer 20

B

Question 21

Evacuate the system by using a ___ to make all the moisture vaporize

charging hose
manometer
torch
vacuum pump

Answer 21

D

Question 22

One useful method of detecting leaks is using a ___ leak detector

chromatographic
electronic
high frequency
infrared

Answer 22

B

Question 23

Relative humidity can be measured directly with an

dewpoint thermometer
hydrometer
hygrometer
psychrometric chart

Answer 23

C

Question 24

Which of the following is a correct match between an electrical valve and the instrument used to measure it?

current, ohmmeter
current, wattmeter
power, ammeter
resistance, ohmmeter

Answer 24

D

Question 25

Identify the line that correctly matches one of the classes of work area hazard to and example of that class of hazard chemical, container of refrigerant mechanical, aluminum ladder physical, unguarded belt drive temperature, heatstroke

Answer 25

A