HVAC Refrigeration: Charging, Piping, Brazing & Evacuation, HVAC Refrigeration Fundamentals: Piping, Evacuation & Heat Transfer, HVACR Fundamentals: Thermodynamics, Refrigerants & System Components, HVAC Refrigeration Midterm: Charging, Thermodynamic…

What should enter the metering device in a refrigeration system?

Only liquid refrigerant

When installing a refrigeration system, how should the piping be connected?

With as few joints as possible

Which statement is true about bending copper tubing?

Only soft copper tubing should be bent

What is true about brazing compared to soldering?

Brazing is done at higher temperatures than soldering

How does atmospheric pressure change at higher altitudes?

It is lower than at sea level

What happens to the boiling point of water at higher altitudes?

It is lower than at sea level

Why is good ventilation important when working around refrigeration equipment?

Modern refrigerants can poison you and displace the oxygen around you

What is the primary difference between a deep-vacuum evacuation and a triple evacuation?

The triple evacuation is done three times

Which temperature is the warmest?

77°F

Why should flux be used when soldering?

It helps prevent oxidation.

Can ABS and PVC pipe be used to carry new blended refrigerants in low-temperature applications?

True

How does atmospheric pressure at higher altitudes compare to sea level?

Lower

Why is good ventilation important when working around refrigeration equipment?

Modern refrigerants are heavier than air and may displace the oxygen around you.

What is the primary difference between a deep-vacuum evacuation and a triple evacuation?

The triple evacuation is done three times.

At which temperature on the Celsius scale does all molecular motion stop?

-273°C

What is an advantage of mechanical piping connections?

They may save time during installation.

What is an air-conditioning system that moves heat at a rate of 24,000 Btu/h referred to as?

A 2-ton system.

What is the designated cylinder color for R410A?

Aqua

What is glide in relation to blended refrigerants?

The range of temperatures/pressures in which a blended refrigerant will condense.

What are the most common fluid mediums used to transfer heat in heating and air-conditioning trades?

Air and water.

What is the size indicated for the diameter of copper tubing used for plumbing?

Inside diameter.

What is the best method of leak checking in a refrigeration system?

In a vacuum.

How can a leak be ruled out?

After two negative tests lasting at least 10 minutes each.

What is the correct sequence for searching pressure-dependent leaks in a system?

Condenser, evaporator, liquid line

What is the term for the amount of heat a refrigerant contains with -40 °F as the reference point?

Enthalpy

Is it true that refrigerant can be added in liquid form into the high-pressure side of the system while the motor-compressor assembly is running?

True

What does the first law of thermodynamics state about energy?

Energy can be neither created nor destroyed

What is the Celsius equivalent of 80°F?

26.7°C

Does water at 0°F have any heat energy or molecular activity?

False

What is the standard atmospheric pressure at sea level?

29.92 in. Hg

What is the purpose of piping and tubing in the HVACR industry?

It provides a path for refrigerant flow between system components.

What type of copper tubing is used in the field piping of refrigeration systems?

ACR

What type of heat changes the temperature of a substance?

Sensible heat

When water at 212°F boils, is it only absorbing latent heat?

True

If the tank is reusable and there are no check valves, can system refrigerant enter the tank as long as the system pressure is higher than the tank pressure?

True

What type of compressor is a positive displacement compressor used for larger conditioning and refrigeration applications?

Screw compressor

What is the bubble point?

The temperature at which saturated liquid first starts to boil

What must moisture in a liquid state do before it can be removed with a vacuum pump?

Be vaporized

What must a technician do when charging a cooling system that uses a TXV?

Charge the refrigerant in liquid form.

What happens to a refrigerant cylinder when charging a system with vapor refrigerant?

The cylinder will become very cold.

What is the boiling point of water in Fahrenheit?

212°F.

What type of leak occurs when temperature, vibration, and pressure cause gas to escape?

Combination leak.

What is fractionation in refrigerants?

It occurs when the saturation temperature for a refrigerant blend varies with pressure.

What is the abbreviation for the plastic pipe used in hot- and cold-water supply systems?

PVC.

At which temperature on the Fahrenheit scale does all molecular motion stop?

-460°F.

What is latent heat?

Heat that is added without a temperature rise.

What happens to molecules in a material as its temperature increases?

They travel faster.

What is the correct refrigerant charge for a split system using R-22 with given specifications?

7 lb 11 oz.

Where is the refrigerant vapor superheated?

In the evaporator.

What is used to take pressure readings on the high-pressure side of a system?

Service port.

What does the unit in. Hg measure?

The height of a column of mercury in a barometer.

Can a manufacturer's charging chart be used to determine the correct charge for a system?

True.

What must be done when charging a refrigeration system with a near-azeotropic mixture to prevent liquid from entering?

Charge as a liquid through the low side using a restrictor.