432

Question 1

If you increase the pressure of a liquid, its _____ temperature will ______, meaning that it will boil at a higher temperature.

Answer 1

saturation; increase

Question 2

At a temperature of -30°F, the enthalpy of the saturated liquid refrigerant (h_f) is 3.5 Btulb. The enthlapy of evaporation (h_fg) is 87.4 Bulb. What is the enthalpy

Answer 2

90.9 Btu,lb

Question 3

In the following diagram of a refrigeration cycle, the line between points ____ represents the amount of subcooling.

Answer 3

2 & 3

Question 4

A system must provide 8 tons of refrigeration. What horsepower is needed for this system? Choose values from the list below when making your calculations:

Answer 4

10.3 hp

Question 5

Liquid refrigerant can be subcooled by transferring heat either to the atmosphere in the condenser or to the _____ in the suction line heat exchanger.

Answer 5

refrigerant vapor

Question 6

An “ideal” refrigerant has which of the following characteristics?

Answer 6

Nonflammable

Question 7

In the ASHRAE standard designations of refrigerants, the

Answer 7

letter R is being replaced by letters identifying the chemical structure

Question 8

Temperature glide occurs only in _____ refrigerants

Answer 8

Blended

Question 9

ASHRAE classifies refrigerants according to how hazardous they are. The most hazardous refrigerants are rated ______

Answer 9

B3

Question 10

When handling out and storing refrigerants, you must protect yourself by

Answer 10

avoiding any open flame

Question 11

The ozone layer in the earth’s atmosphere is important, because it

Answer 11

absorbs ultraviolet radiation from the sun

Question 12

CFCs contribute to the greenhouse effect by

Answer 12

absorbing infrared radiation

Question 13

In order to minimize the release of CFCs into the atmosphere, refrigeration service technicians must

Answer 13

recycle refrigerants on-site, if possible

Question 14

A recycled refrigerant may be placed in

Answer 14

the system from which it was removed

Question 15

During the installation of a new system, the chance of future refrigerant leaks can be reduced by

Answer 15

installing a muffler in the compressor discharge line

Question 16

To reduce the depletion of the ozone layer, the U.S. government has implemented laws requiring the

Answer 16

testing and certfication of all technicians whose work can cause the release of harmful refrigerants

Question 17

The EPA’s final rule concerning the handling of refrigerants and refrigeration equipment requires

Answer 17

certifying the equipment used in recycling and reclaiming refrigerants

Question 18

The compressor for an active recovery system is part of the ____. The compressor for a passive recovery system is part of the ______.

Answer 18

recovery equipment, system being serviced

Question 19

Technicians who work on residential air conditioning systems must have at least _____ certification

Answer 19

Type II

Question 20

Which of the following documents is required by the EPA?

Answer 20

Certification activity report

Question 21

Which of the following is a contaminant that can be removed by a filter-drier?

Answer 21

Acid

Question 22

An absorption-type desiccant holds water by means of a(n) _____ action, but an adsorption-type desiccant holds water by means of a(n)_____ action

Answer 22

chemical; mechanical

Question 23

If you mount a filter-drier in a vertical suction line, the inlet should be located at the top so that _____ cannot become trapped inside.

Answer 23

Oil

Question 24

When selecting a filter-drier, you need to base your selection in part on the

Answer 24

minimum particle size it can trap

Question 25

When installing a filter-drier in a refrigeration system, you should

Answer 25

wear safety goggles

Question 26

You can pinpoint leaks in a new refrigeration system by charging the system with ____ and using a _____

Answer 26

nitrogen, soap solution

Question 27

When preparing to use a gauge manifold in servicing a pressurized refrigeration system, you connect its high-side charging hose to the

Answer 27

compressor discharge service valve

Question 28

To check the charge in a refrigeration system, you can look at the _____ in the liquid line. If the charge is low, you will probably see

Answer 28

sight glass, bubbles

Question 29

In using the deep-vacuum method of dehydrating a refrigeration system, you lower the pressure to about _____ microns or less. With the vacuum pump turned off, a gradual rise in pressure tells you the system is

Answer 29

1,000, not dry

Question 30

You can tell whether you have charged a refrigeration system with the correct amount of refrigerant by checking the

Answer 30

weight of the refrigerant used

Question 31

The miscibility of a refrigerant oil is its ability to

Answer 31

Mix with the refrigerant

Question 32

Oil that becomes mixed with the refrigerant in a system can cause which of the following problems?

Answer 32

Clogged desiccant

Question 33

An oil separator is located between the ____ and the _____ in order to keep oil out of the condenser and evaporator.

Answer 33

compressor, condenser

Question 34

Moisture in a refrigeration system causes a variety of problems, including

Answer 34

blockage in cold parts of the system

Question 35

Before you check the oil level in the sight- glass on a refrigeration compressor, you should stop the compressor for at least _____. The compressor should be _____

Answer 35

ten minutes; stopped