Mechanical Engineering Unit 11 To 20 Refrigerant Blend With Glide More Would Considered Low Glide Blend Azeotrope Compound

313)

A refrigerant blend with a glide of 10°F or more would be considered:

A)

A low glide blend.

B)

An azeotrope.

C)

A compound.

D)

A high glide blend.

Answer:

D

Explanation:

A)

B)

C)

D)

314)

What does a crankcase pressure regulator do?

A)

It maintains the oil pressure in the compressor crankcase.

B)

It will not allow the compressor suction pressure to drop below the CPR setpoint.

C)

It maintains a positive crankcase pressure by bypassing small quantities of discharge gas

into the crankcase.

D)

It will not allow the compressor suction pressure to rise above the CPR setpoint.

Answer:

D

Explanation:

A)

B)

C)

D)

315)

What are the two basic types of relief valves used on refrigeration systems?

A)

Electrically operated and pneumatically operated

B)

An automatic relief valve and a one–time relief valve

C)

System mounted and remote mounted

D)

A high–side pressure relief valve and a low–side pressure relief valve

Answer:

B

Explanation:

A)

B)

C)

D)

316)

Which of the following are used to separate and collect some of the oil in the discharge line as it

leaves the compressor and then return it to the compressor’s crankcase?

A)

Oil separators

B)

Refrigerant separators

C)

Heat separators

D)

Water separators

Answer:

A

Explanation:

A)

B)

C)

D)

81

317)

What are the most common desiccant materials used in driers?

A)

Activated carbon and alcohol

B)

Molecular sieve and activated alumina

C)

Activated alumina and activated charcoal

D)

Alcohol and hydrogen peroxide

Answer:

B

Explanation:

A)

B)

C)

D)

318)

Where in the system is an oil separator installed?

A)

In the suction line leaving the evaporator

B)

In the liquid line leaving the condenser

C)

An oil separator can be installed anywhere in the system.

D)

In the discharge line leaving the compressor

Answer:

D

Explanation:

A)

B)

C)

D)

319)

Using heat–reclaim coils will help improve a building’s overall:

A)

Cooling efficiency.

B)

Humidity level.

C)

Heat efficiency.

D)

Pressure level.

Answer:

C

Explanation:

A)

B)

C)

D)

320)

When installing a solenoid valve:

A)

The coil should be tested by energizing it off the valve.

B)

The arrow stamped on the body should point in the direction of flow.

C)

The coil should always be located on the underside of the valve.

D)

The arrow stamped on the body points toward the valve inlet port.

Answer:

B

Explanation:

A)

B)

C)

D)

82

321)

What is subcooling?

A)

Lowering refrigerant temperature below 0°F

B)

Lowering refrigerant temperature below freezing

C)

Lowering liquid refrigerant temperature below its saturation temperature

D)

Lowering refrigerant temperature by flashing some of it off to a gas, cooling the remaining

liquid

Answer:

C

Explanation:

A)

B)

C)

D)

322)

An isothermal process is a process that does not change:

A)

The pressure of the refrigerant.

B)

The volume of the refrigerant.

C)

The temperature of the refrigerant.

D)

The state of the refrigerant.

Answer:

C

Explanation:

A)

B)

C)

D)

323)

Refrigerant characteristics shown on a pressure–enthalpy diagram include:

A)

Molecular weight, valence, specific gravity, and atomic number.

B)

Molecular weight, specific heat factor, and density.

C)

Pressure, heat, and temperature.

D)

Valence, atomic number, and specific volume.

Answer:

C

Explanation:

A)

B)

C)

D)

83

324)

How is placement of the compressor line determined when drawing a PH diagram of an

operating system?

A)

The compressor line starts where the evaporator line crosses the suction line temperature

and follows the constant quality lines up until it crosses the condenser line.

B)

Measure the suction–line temperature entering the compressor. Find where the evaporator

line crosses this suction line temperature in the superheated area.

C)

The compressor line starts where the condenser line crosses the suction line temperature

and follows the constant entropy lines up until it crosses the evaporator line.

D)

The compressor line starts where the evaporator line crosses the suction line temperature

and follows the constant enthalpy lines up until it crosses the condenser line.

Answer:

B

Explanation:

A)

B)

C)

D)

325)

Where in the cycle does heat enter the refrigerant?

A)

Some heat is added in every component.

B)

In the evaporator and compressor

C)

In the evaporator and condenser

D)

In the compressor and condenser

Answer:

B

Explanation:

A)

B)

C)

D)

326)

Refrigerant increases in volume as it travels through the:

A)

Condenser.

B)

Compressor.

C)

Entropy.

D)

Metering device.

Answer:

D

Explanation:

A)

B)

C)

D)

84

327)

On a typical plot of the refrigeration cycle, where does liquid refrigerant first begin forming in the

condenser?

A)

Where the condenser line (the top line) crosses the saturation curve from the superheated

region

B)

In the middle of the condenser line (the top line)

C)

At the start of the condenser line (the top line), immediately after the compressor line

D)

At the end of the condenser line where it crosses the saturation curve into the subcooling

region

Answer:

A

Explanation:

A)

B)

C)

D)

328)

What units are used to indicate specific enthalpy?

A)

BTU lb

B)

BTU

C)

BTU/lb

D)

Degrees Fahrenheit

Answer:

C

Explanation:

A)

B)

C)

D)

329)

How is placement of the condenser line determined when drawing a PH diagram of an operating

system?

A)

Draw a horizontal line across the saturation curve on the constant pressure line equal to the

system high–side absolute pressure.

B)

The condenser line can be drawn anywhere that crosses the saturation curve as long as it is

a horizontal line.

C)

Draw a vertical line across the saturation curve on a constant enthalpy line equal to the

system high–side absolute temperature.

D)

The condenser line is always drawn on the horizontal line representing 275 psia absolute

pressure.

Answer:

A

Explanation:

A)

B)

C)

D)

85

330)

Which of the refrigerant ratings indicates that a refrigerant is considered a higher–toxicity

refrigerant?

A)

B1

B)

A2

C)

A3

D)

A1

Answer:

A

Explanation:

A)

B)

C)

D)

331)

Who can legally refill a DOT 39 nonrefillable cylinder?

A)

Nobody

B)

Only the cylinder manufacturer

C)

Only certified technicians

D)

Only the refrigerant manufacturer

Answer:

A

Explanation:

A)

B)

C)

D)

332)

Who may refill a DOT 39 nonrefillable cylinder?

A)

Only refrigerant manufacturers

B)

Only certified technicians

C)

Only EPA–certified refrigerant recyclers

D)

Nobody

Answer:

D

Explanation:

A)

B)

C)

D)

333)

How is the type of service pressure of a recovery tank identified?

A)

By the first numbers listed on the tank

B)

By the first number after the letters “DOT”

C)

By the last group of numbers on the tank

D)

By the listed weight of the tank

Answer:

C

Explanation:

A)

B)

C)

D)

86

334)

If oxygen is under pressure and mixed with refrigerant oil, which of the following will result?

A)

A toxic gas may be released.

B)

There will be no reaction.

C)

An explosion may occur.

D)

A new element will be created.

Answer:

C

Explanation:

A)

B)

C)

D)

335)

Which of the refrigerant ratings indicates that a refrigerant is considered highly flammable?

A)

B2

B)

B1

C)

A1

D)

A3

Answer:

D

Explanation:

A)

B)

C)

D)

336)

What should a technician do with a DOT 39 nonrefillable cylinder when it is empty?

A)

The cylinder should be returned to the refrigerant manufacturer to be reused.

B)

Recover any remaining refrigerant, open the valve, knock out the relief disk, and label it

EMPTY.

C)

Once most of the refrigerant has been used, the residual may be released to the air.

D)

Knock out the relief disk to remove the residual refrigerant and label the cylinder empty.

Answer:

B

Explanation:

A)

B)

C)

D)

337)

Which of the refrigerant ratings indicates that a refrigerant is considered nonflammable?

A)

A3

B)

B2

C)

A2

D)

B1

Answer:

D

Explanation:

A)

B)

C)

D)

87

338)

A biflow expansion valve:

A)

Has both a low flow and a high flow setting.

B)

Can be used with two different refrigerants.

C)

Is designed to allow refrigerant flow in both directions.

D)

Provides flow out of two ports simultaneously, eliminating the need for a refrigerant

distributor.

Answer:

C

Explanation:

A)

B)

C)

D)

339)

A system with a loose TEV sensing bulb would most likely:

A)

Have a low superheat.

B)

Have a high superheat.

C)

Have a lower–than–normal evaporator pressure.

D)

Need adjusting to compensate for the poor bulb installation.

Answer:

A

Explanation:

A)

B)

C)

D)

340)

Besides distributing the refrigerant evenly, a refrigerant distributor also:

A)

Creates a pressure drop across the distributor.

B)

Filters the refrigerant.

C)

Lubricates the system by infusing small quantities of refrigerant oil.

D)

Agitates the refrigerant to flash off as much as possible.

Answer:

A

Explanation:

A)

B)

C)

D)

341)

The two general categories of metering devices are:

A)

High pressure and low pressure.

B)

Copper and brass.

C)

Pressure–reducing and pressure–increasing.

D)

Fixed and modulating.

Answer:

D

Explanation:

A)

B)

C)

D)

88

342)

Where is the suction line temperature read when adjusting a TEV?

A)

As close as possible to the TEV bulb

B)

As close as possible to the discharge service valve

C)

At the inlet of the compressor

D)

At the inlet of the evaporator

Answer:

A

Explanation:

A)

B)

C)

D)

343)

The superheat is 12°F. What is the suction line temperature if the evaporator saturation

temperature is 35°F?

A)

23°F

B)

47°F

C)

10°F

D)

17°F

Answer:

B

Explanation:

A)

B)

C)

D)

344)

When applied to systems with air–cooled condensers, what is the lowest outside ambient

temperature at which balanced–port valves can typically work without head pressure control?

A)

45°F

B)

25°F

C)

35°F

D)

15°F

Answer:

C

Explanation:

A)

B)

C)

D)

345)

The wet coil static pressure drop is:

A)

Can only be determined when the coil is submerged in water.

B)

Higher than the dry coil static pressure drop.

C)

About the same as the dry coil static pressure drop.

D)

Lower than the dry coil static pressure drop.

Answer:

B

Explanation:

A)

B)

C)

D)

89

346)

In a flooded chiller:

A)

The water and refrigerant are in separate tubes with a heat transfer medium in the shell.

B)

The water and refrigerant are mixed in the shell.

C)

The water is in the shell and the refrigerant is in the tubes.

D)

The water is in the tubes and the refrigerant is in the shell.

Answer:

D

Explanation:

A)

B)

C)

D)

347)

An evaporator in which refrigerant enters as a saturated liquid vapor mix and leaves as a

superheated vapor is a:

A)

Flooded evaporator.

B)

Carbureting evaporator.

C)

Saturated evaporator.

D)

Direct expansion evaporator.

Answer:

D

Explanation:

A)

B)

C)

D)

348)

On a commercial refrigeration system with hot–gas defrost, what does the compressor do during

the defrost cycle?

A)

It runs backwards to pump hot gas into the evaporator.

B)

It cycles like it normally would.

C)

It operates to provide the heat for defrost.

D)

It shuts off.

Answer:

C

Explanation:

A)

B)

C)

D)

349)

The substance being cooled by a refrigeration system is called:

A)

The cooling medium.

B)

The refrigerant.

C)

The source.

D)

The product.

Answer:

D

Explanation:

A)

B)

C)

D)

90

350)

How deep should the condensate drain trap be?

A)

4 inches deep

B)

6 inches deep

C)

1 inch deep

D)

12 inches deep

Answer:

A

Explanation:

A)

B)

C)

D)

351)

What happens to the evaporator fan motor when the defrost cycle is terminated?

A)

The fan runs at a higher speed until the evaporator has cooled back down.

B)

The fan shuts off until the defrost termination thermostat senses that the evaporator is cold

again.

C)

The fan stops running backwards and begins to operate normally again.

D)

The fan comes back on to cool the freezer.

Answer:

B

Explanation:

A)

B)

C)

D)

352)

When water gets into a refrigeration system, chemical reactions inside the system often create:

A)

Phosgene gas.

B)

Combustible gas.

C)

Acid.

D)

Fluoride crystals.

Answer:

C

Explanation:

A)

B)

C)

D)

353)

The standard industry number designation for each refrigerant is assigned by:

A)

NIST – National Institute for Standards and Testing.

B)

AHRI – Air Conditioning Heating and Refrigeration Institute.

C)

RSES – Refrigeration Service Engineer’s Society.

D)

ASHRAE – American Society of Heating, Refrigeration and Air Conditioning Engineers.

Answer:

D

Explanation:

A)

B)

C)

D)

91

354)

A hygroscopic lubricant:

A)

Absorbs water readily.

B)

Is water repellant.

C)

Is an oil whose composition is based on water.

D)

Is used primarily with water–cooled systems.

Answer:

A

Explanation:

A)

B)

C)

D)

355)

Contaminants that can be found in recovered refrigerant include:

A)

Water and acid.

B)

Carbon and particulates.

C)

Carbon, oil, noncondensables, water, and acid.

D)

Oil and noncondensables.

Answer:

C

Explanation:

A)

B)

C)

D)

356)

The chemical in CFCs that contributes to ozone depletion is:

A)

Chlorine.

B)

Fluorine.

C)

Hydrogen.

D)

Carbon.

Answer:

A

Explanation:

A)

B)

C)

D)

357)

Azeotropes are mixtures of two refrigerants:

A)

That are chemically bonded to form a new refrigerant.

B)

That separate when changing state.

C)

That are electromagnetically bonded to form a new refrigerant.

D)

That do not separate when changing state.

Answer:

D

Explanation:

A)

B)

C)

D)

92

358)

What happens to the specific enthalpy as you move to the right or left along a constant

temperature line?

A)

The specific enthalpy increases as you move to the right.

B)

The specific enthalpy increases as you move to the left.

C)

The specific enthalpy remains the same.

D)

The specific enthalpy is not related in any way to movement along the constant pressure

line.

Answer:

A

Explanation:

A)

B)

C)

D)

359)

Which of the following is the line that drops straight down because no heat is gained or lost?

A)

Entropy

B)

Condenser

C)

Compressor

D)

Metering device

Answer:

D

Explanation:

A)

B)

C)

D)

360)

The required system capacity in tons can be determined by dividing:

A)

100 BTU/min by the system’s refrigeration effect.

B)

300 BTU/min by the system’s refrigeration effect.

C)

600 BTU/min by the system’s refrigeration effect.

D)

200 BTU/min by the system’s refrigeration effect.

Answer:

D

Explanation:

A)

B)

C)

D)

361)

The lines inside the saturation curve that start at the bottom and extend upward toward the

critical point are called:

A)

Critical pressure lines.

B)

Critical temperature lines.

C)

Saturation lines.

D)

Constant quality lines.

Answer:

D

Explanation:

A)

B)

C)

D)

93

362)

The lines that run horizontally from the right side to the left side of the diagram are which of the

following?

A)

Pressure lines

B)

Constant quality lines

C)

Curved lines

D)

Saturation curves

Answer:

A

Explanation:

A)

B)

C)

D)

363)

A large release of refrigerant in a machine room has caused a co–worker to pass out. You should:

A)

Work slowly and methodically to keep your pulse and respiration rate low.

B)

Put on self–contained breathing apparatus before going to get them.

C)

Get to them as quickly as possible and drag them to safety.

D)

Hold your breath while dragging them out.

Answer:

B

Explanation:

A)

B)

C)

D)

364)

Bare skin exposed to liquid refrigerant will:

A)

Tingle, but not be seriously harmed.

B)

Withstand 30 seconds of immersion.

C)

Become immediately stiff and hard like an ice cube.

D)

Feel like a burn and blister up.

Answer:

D

Explanation:

A)

B)

C)

D)

365)

Skin exposed to streams of liquid refrigerant can receive:

A)

Cardiac arrhythmia.

B)

A tingling effect.

C)

Convulsions and vomiting.

D)

A burn from the subzero liquid.

Answer:

D

Explanation:

A)

B)

C)

D)

94

366)

What is the maximum safe storage temperature for refrigerant cylinders?

A)

150°F

B)

100°F

C)

175°F

D)

125°F

Answer:

D

Explanation:

A)

B)

C)

D)

367)

What type of sensor is most often used to detect very low parts per million for toxic refrigerants?

A)

Electrochemical (EC) sensors

B)

Photoacoustic infrared (PIR)

C)

Ceramic metal oxide semiconductor (CMOS)

D)

Nondispersive infrared (NDIR)

Answer:

A

Explanation:

A)

B)

C)

D)

368)

The purpose of the trap in a condensate drain is to:

A)

Provide a place for coil slime to collect so that is can be easily cleaned out.

B)

Keep snakes and insects from crawling up the drain into the coil.

C)

Offset the negative pressure on the drain, which can prevent the water from draining.

D)

Ensure that some water is always standing in the evaporator drain pan.

Answer:

C

Explanation:

A)

B)

C)

D)

369)

The percentage of air that travels through a tube–and–fin coil without touching any coil surface is

called the:

A)

Sensible heat ratio.

B)

Dilution air percentage.

C)

Bypass factor.

D)

Volumetric efficiency.

Answer:

C

Explanation:

A)

B)

C)

D)

95

370)

On a commercial refrigeration system with electric defrost, what does the compressor do during

the defrost cycle?

A)

It shuts off.

B)

It runs backwards to pump hot gas into the evaporator.

C)

It cycles like it normally would.

D)

It operates to provide the heat for defrost.

Answer:

A

Explanation:

A)

B)

C)

D)

371)

What controls the length of the defrost cycle on most commercial refrigeration systems?

A)

The high–pressure switch

B)

The defrost termination thermostat

C)

The defrost timer

D)

The evaporator fan motor

Answer:

B

Explanation:

A)

B)

C)

D)

372)

New residential air–conditioning systems now primarily use:

A)

HFC–410A.

B)

CFC–12.

C)

HFC–134a.

D)

HCFC–22.

Answer:

A

Explanation:

A)

B)

C)

D)

373)

Fractionation can occur within zeotropic refrigerating when they:

A)

Mix.

B)

Change state.

C)

Change temperature.

D)

Freeze.

Answer:

B

Explanation:

A)

B)

C)

D)

96

374)

Refrigerants absorb heat:

A)

By converting heat energy into additional refrigerant molecules.

B)

By condensing from a vapor to a liquid.

C)

By rearranging their molecular structure to form a new compound.

D)

By evaporating from a liquid to a vapor.

Answer:

D

Explanation:

A)

B)

C)

D)

375)

What are the chemical components of HFC refrigerant?

A)

Helium, fluorine, and chlorine

B)

Hydrogen, fluorine, and carbon

C)

Hydrogen, Freon, and chromium

D)

Helium, Freon, and chlorine

Answer:

B

Explanation:

A)

B)

C)

D)

376)

How is placement of the evaporator line determined when drawing a PH diagram of an operating

system?

A)

The evaporator line can be drawn anywhere that crosses the saturation curve as long as it is

a horizontal line.

B)

The evaporator line is always drawn on the horizontal line representing 50 psia absolute

pressure.

C)

Draw a horizontal line across the saturation curve on the constant pressure line equal to the

system low–side absolute pressure.

D)

Draw a vertical line across the saturation curve on a constant enthalpy line equal to the

system low–side absolute temperature.

Answer:

C

Explanation:

A)

B)

C)

D)

377)

What is the refrigeration effect of a system if the liquid entering the evaporator has an enthalpy of

60 BTU/lb and the vapor leaving the evaporator has an enthalpy of 110 BTU/lb?

A)

110 BTU/lb + 60 BTU/lb = 170 BTU/lb

B)

110 BTU/lb

C)

110 BTU/lb – 60 BTU/lb = 50 BTU/lb

D)

110 BTU/lb/60 BTU/lb = 1.83 BTU/lb

Answer:

C

Explanation:

A)

B)

C)

D)

97

378)

As the refrigerant temperature drops during the desuperheating phase of the refrigeration cycle,

the refrigerant pressure:

A)

Increases due to the inverse relationship between temperature and pressure.

B)

Drops also due to the temperature drop.

C)

There is no definite relationship between refrigerant pressure and refrigerant temperature.

D)

Remains the same.

Answer:

D

Explanation:

A)

B)

C)

D)

379)

How would high levels of inhalation of a refrigerant affect an individual?

A)

No adverse reaction would occur.

B)

Cardiac arrhythmia may occur

C)

Delusions may be possible.

D)

The skin may burn.

Answer:

B

Explanation:

A)

B)

C)

D)

380)

Which of the refrigerant ratings indicates that a refrigerant is considered a lower–toxicity

refrigerant?

A)

B3

B)

B2

C)

A3

D)

B1

Answer:

C

Explanation:

A)

B)

C)

D)

381)

Which type of glove should be used if prolonged contact with liquid or gas is expected?

A)

Leather

B)

PVA

C)

Cloth

D)

Plastic

Answer:

B

Explanation:

A)

B)

C)

D)

98

382)

How can a technician verify that a condenser and evaporator are an AHRI match?

A)

Check them out on the AHRI web site.

B)

Check with the EPA.

C)

Ask the salesman at the parts counter.

D)

The correct matches are printed on the unit nameplate.

Answer:

A

Explanation:

A)

B)

C)

D)

383)

Refrigerant enters a direct expansion evaporator as a saturated mixture and leaves as a:

A)

Warm vapor.

B)

Cool vapor.

C)

Saturated mixture.

D)

Superheated vapor.

Answer:

D

Explanation:

A)

B)

C)

D)

384)

How is a brine solution created?

A)

Salt and water are mixed.

B)

Water and sugar are mixed.

C)

Salt and air are mixed.

D)

Salt and sugar are mixed.

Answer:

A

Explanation:

A)

B)

C)

D)

385)

The halogen family of chemicals includes:

A)

Oxygen, carbon, and hydrogen.

B)

Carbon and hydrogen.

C)

Chlorine, fluorine, and bromine.

D)

All the chemical elements found in refrigerants are halogens.

Answer:

C

Explanation:

A)

B)

C)

D)

99