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 degrees the enthalpy of the saturated liquid refrigerant is 3.5 btu/lb the enthalpy of evaporation is 87.4 btu/lb what is the enthalpy of the saturated vapor

Answer 2

90.9

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

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 the 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 refrigerant 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 earths 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 in to 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 refrigeration 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 US government has implemented laws requiring the

Answer 16

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

Question 17

the EPAs final rule concerning the handling of refrigerants and refrigerant 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 an ___ action but an adsorption type desiccant holds water by means of an ___ 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

1000; 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 refrigerants

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 __ 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 ___ while you check the oil level

Answer 35

ten minutes; stopped