Chapter 9 Test 10/31

What percentage of moisture and particulates must be removed from reclaimed refrigerants?

100%

Calculate the tare weight of a cylinder if its total weight is 590 lb, and the weight of refrigerant in the cylinder is 450 lb.

140 lb

What is the superheat of a system if the refrigerant temperature in the suction line is 58°F, its pressure in the evaporator is 60 psig, and its temperature in the evaporator is 34°F?

24°F

A ton of refrigeration is equal to ____.

288000 Btu/24-hr.

There are ______________________________ divisions in the classification for flammability of refrigerants.

4

A gauge should not be exposed to pressure greater than ____ of its full-scale range for more than a few minutes.

75%

What is the maximum amount of refrigerant that a recovery cylinder should contain?

80% water capacity by weight.

All refrigerant cylinders should be secured with ____ when they are being transported.

A chain

According to the ASHRAE classification for refrigerants, the classification for the least toxic and least flammable refrigerants is ____.

A1

Ice melts in iceboxes because ____.

All of the above

MFT-R-500 is a blend refrigerant of this type.

Azeotropic

If the valve stem is turned counterclockwise as far as possible, the service valve is in the ____ position.

Back seated

Due to their high ozone depletion potential, ____ refrigerants were targeted first for phaseout by the Montreal Protocol.

CFC

Coefficient of performance is the ratio of refrigeration effect to the heat of ______________________________.

Compression

A suction service valve connects to the suction line and directly onto the ____.

Compressor at its inlet

The range of temperatures from -250°F to near absolute zero is referred to as the ______________________________ range.

Cryogenic

MFT-Refers to extremely low refrigerant temperatures.

Cryogenics

A pressure-temperature curve shows that pressure and temperature are ____ in a refrigeration system.

Directly Related

Also referred to as chemical refrigeration or open-cycle refrigeration, ______________________________ refrigeration systems use a refrigerant only once.

Expendable

MFT-Type of refrigerant that is used and then released to the atmosphere.

Expendable

A gauge that reads absolute pressure should be adjusted depending on the elevation.

False

Both valves need to be closed on a gauge manifold in order to evacuate a system.

False

Carbon Dioxide is classified as an organic refrigerant(600 series)

False

Cylinder color-coding is a requirement for manufacturers, so technicians do not need to check labels.

False

Disposable cylinders are designed to be used for refrigerant recovery.

False

Electronic leak detectors can only be used to detect CFCs.

False

For the refrigeration system to operate correctly, the condenser must always be at a lower saturation temperature than the evaporator.

False

HCFCs have an ODP rating of 0.

False

HFCs were the first type of refrigerant to be produced.

False

If a cylinder of R-22 is moved from a 100°F truck body into an 80°F shop, the quantity of liquid refrigerant in the cylinder will remain the same. True

False

Refrigerant is reclaimed on the job site.

False

Service technicians can safely use formulas and tables to mix their own azeotropic refrigerant blends.

False

The refrigerant temperature in the evaporator is the same as the evaporator temperature when the unit is running.

False

Vapor is more dense than liquid and, as the liquid refrigerant boils, it has a tendency to sink.

False

The separation of the individual refrigerants in a zeotropic blend during phase change is known as ____.

Fractionation

Halogens cause the torch of a flame to turn ____ when they are brought into contact with heated copper.

Green

MFT-Refrigerant with 0 ODP, low GWP, and high flammability, used in some new standalone refrigerators and freezers

HCs

Because they cannot be mixed with mineral oils, ____ refrigerants use synthetic oils for lubrication.

HFC

MFT-Refrigerant with 0 ODP, low GWP, and low toxicity, used in some new automotive applications.

HFOs

Which type of gauge is designed to read pressure values on a single continuous scale and be used on the high side of a system?

High-pressure gauge

If a refrigerant belongs to the 700 series in the refrigerant numbering system, then it is ____.

Inorganic

MFT-Cylinder color code for R-22 cylinders.

Light Green

Drawing an extremely low pressure in a refrigeration system is necessary to remove ____ from the system.

Moisture

Refrigerant blends that react similarly to zeotropes but respond over a smaller range of boiling and condensation points are called ______________________________.

Near-azeotropes

How many times can an expendable refrigerant be used?

Once

The ______________________________ layer is a thin layer in the earth's upper atmosphere that helps filter ultraviolet rays.

Ozone

The lowest temperature at which a lubricant will flow is called the ____.

Pour Point

The ODP scale compares the destructive potential of different chemicals to the destructive potential of ______________________________.

R-11

MFT-Refrigerant used as a replacement for R-11.

R-123

MFT-HFC refrigerant

R-134a

Which zeotropic refrigerant blend is used as a replacement for R-22 in air-conditioning applications, but operates at a higher temperature and pressure?

R-410A

Which of the following refrigerants has the lowest boiling temperatures at atmospheric pressure?

R-502

MFT-Refrigerant used in absorption systems.

R-717

Refrigerant ____ is the process of removing refrigerant from a system and storing it in a cylinder.

Recovery

Which type of refrigerant cylinder is gray on the bottom and yellow on the top?

Recovery

The cylinder color code for R-134a is ____.

Sky blue

A Bourdon tube ____ as pressure inside it increases.

Straightens

If heat is added to a saturated vapor and raises the vapor's temperature above its boiling point, the heat is referred to as ____.

Superheat

MFT-Unique characteristic of zeotropic blends.

Temperature Glide

What happens when room temperature soda is poured into a glass of ice?

The ice melts because it is absorbing heat from the soda.

The ability of a refrigerant to be harmful or lethal with exposure is referred to as its ______________________________.

Toxicity

Which evacuation method involves charging a system with nitrogen to absorb moisture?

Triple evacuation.

A higher coefficient of performance means that a refrigerant produces its refrigeration effect more efficiently.

True

A refrigerant blend containing an HCFC and a CFC is considered a CFC.

True

An expansion valve is the pressure reducing device that controls the flow of liquid refrigerant into the evaporator.

True

Each time a recovery/recycling machine is used, the filter-drier should be changed.

True

In a zeotropic refrigerant blend, the refrigerant with the lowest boiling point boils first.

True

Modern refrigerators have become state-of-the-art appliances and some models even include automatic beverage and ice dispensers, built in television screens and connections to the World Wide Web.

True

Only liquid refrigerant should enter the metering device.

True

R-134a has been used as a replacement refrigerant for systems that use R-12.

True

R-22 and R-123 are classified as HCFC refrigerants.

True

Refrigerant must be recovered from a leaking system before repairs can be performed.

True

The discharge gas from the compressor is a high pressure, high temperature, superheated vapor.

True

The evaporator can be thought of as a "heat sponge".

True

The halide leak detector should be used in well ventilated areas as the resulting blue or green flame indicates that phosgene gas is being produced.

True

The liquid receiver service valve (king valve) should be front seated in order to perform a pump-down.

True

The pressure of a perfect vacuum is 29.92 in. Hg.

True

Vacuum pump oil turns ____ when it is contaminated by water.

White and Foamy

Reciprocating compressors have ____.

a piston and cylinder

The evaporator in a refrigeration system ____.

absorbs heat from the product to be cooled

The law requires technicians to recover refrigerant from all refrigeration systems so that they ____.

all of the above

High temperature refrigeration is that produced by ____.

an air-conditioning system

Good ventilation is important when working around refrigeration equipment because modern refrigerants ____.

are heavier than air and may displace the oxygen around you

The pressure in a refrigeration system is changed in the ____.

compressor and expansion device

To determine a system's subcooling value, the liquid line temperature should be subtracted from the ____ temperature.

condenser

The refrigerant in a refrigeration system changes state in the ____.

condenser and evaporator

At what location or locations in a refrigeration system does the saturation pressure correspond to the saturation temperature?

evaporator and condenser

Two-part epoxy resin kits usually include one tube filled with epoxy and another tube filled with a(n) ____.

hardener

If the entire refrigerant charge has leaked out of a system, then a(n) ____ should be used to pressurize the system to test for leaks.

inert gas

Many recovery cylinders use a(n) ____ as a safety device to turn off the recovery machine when the cylinder is 80% full.

liquid level switch

When a refrigerant enters the compressor, it is a ____ and when it leaves the compressor, it is a ____.

low pressure low temperature superheated vapor, high pressure high temperature superheated vapor

When charging a system with refrigerant, the technician should put the low- and high-side service valves in _____.

mid-position

Pressure that is greater than atmospheric pressure is referred to as ____ pressure.

positive

The process of pumping a system's entire refrigerant charge into the liquid receiver is called a(n) ____.

pump-down

The compressor in a refrigeration system ____.

pumps the refrigerant throughout the system

During push-pull liquid recovery, vapor refrigerant is pulled from the ____.

recovery cylinder

The condenser ____.

rejects the heat from the refrigerant

Subcooling refers to the amount of ____ removed from a refrigerant after it has condensed.

sensible heat

Refrigeration can be described as ____.

the process of removing heat from a place where it is not wanted to a place where it makes little or no difference

When a refrigeration unit is off, the temperature of the condenser is ____ the temperature of the refrigerant.

the same as