CTVET Certificate II in Refrigeration and Air Conditioning (Ghana)

Which class of fire extinguisher is specifically designed and rated for extinguishing electrical fires in an HVAC/R workshop?

• AClass A
• BClass B
• CClass C
• DClass D

What is the primary personal protective equipment (PPE) required to protect your eyes when handling or charging liquid refrigerants?

• AStandard reading spectacles
• BImpact-resistant safety goggles or a full face shield
• CPolarized sunglasses
• DA welding hood with dark filter glass

If a coworker is experiencing an electric shock in the refrigeration workshop, what is the very first action you should take?

• AGrab their arm and pull them away from the electrical source
• BThrow water on the coworker to extinguish any electrical sparks
• CImmediately switch off or isolate the main power source
• DAdminister cardiopulmonary resuscitation (CPR) immediately before isolating power

On a standard HVAC/R service manifold gauge set, what is the function of the blue hose?

• AConnecting to the high-pressure discharge side of the system
• BConnecting to the low-pressure suction side of the system
• CConnecting to the vacuum pump or refrigerant recovery cylinder
• DConnecting to the high-pressure liquid refrigerant supply tank

Why must a refrigerant recovery cylinder never be filled with liquid refrigerant beyond 80% of its volume capacity?

• ATo prevent the cylinder from becoming too heavy to carry according to lifting rules
• BTo allow room for liquid expansion when the temperature of the cylinder rises
• CTo ensure that there is enough air left to keep the refrigerant fresh
• DTo maintain a vacuum seal inside the cylinder valve assembly

What unit of measurement is displayed on a digital vacuum gauge to indicate that a deep, high-quality vacuum has been achieved?

• APounds per square inch (psi)
• BInches of mercury (in. Hg)
• CMicrons
• DBar

What is the primary purpose of using a dedicated refrigerant recovery machine during system servicing?

• ATo filter out acid and clean the refrigerant inside the operating unit
• BTo compress air and pressure-test the copper coils for leaks
• CTo extract refrigerant from a system and transfer it to an external storage cylinder with…
• DTo vacuum out moisture and boil off water inside the evaporator coil

Which of the following is the safest and most effective method to locate a small refrigerant leak in a pressurized HVAC/R piping joint?

• AHolding a lit match or candle flame near the joint to see if the flame changes color
• BApplying an approved soap bubble solution or using an electronic leak detector
• CSubmerging the entire joint in a bucket of gasoline to observe chemical reactions
• DListening closely by ear for a whistling sound while the system is turned off

During a system evacuation, if the vacuum pressure rises immediately after turning off the vacuum pump valves and continues to rise toward atmospheric pressure, what does this indicate?

• AThe system has successfully achieved a complete dehydration level
• BThere is an active physical leak in the system piping or connections
• CThe vacuum pump oil is clean and operating at maximum efficiency
• DLiquid refrigerant is boiling off slowly inside the accumulator

What is the primary technical reason for using a reamer on copper tubing after cutting it with a wheel cutter?

• ATo reduce the outside diameter of the tube to fit into smaller fittings
• BTo remove the internal burr created by the cutter to prevent restricted refrigerant flow…
• CTo polish the outer surface of the copper to ensure a shiny brazing joint
• DTo increase the thickness of the copper wall at the joint location

Which type of glove should be worn when handling liquid refrigerants to protect hands against cryogenic burns and frostbite?

• AThin disposable latex gloves
• BInsulated, chemical-resistant work gloves
• CPolyester gardening gloves
• DFingerless wool gloves

On a standard HVAC/R service manifold gauge set, what does the red hose connect to?

• AThe suction service valve or low-pressure port
• BThe discharge service valve or high-pressure port
• CThe vacuum pump inlet connection
• DThe center purging valve

Why is it strictly prohibited to use compressed oxygen or ordinary air to pressurize a refrigeration system for leak testing?

• AOxygen is too expensive to use for routine shop leak testing
• BOxygen and oil under pressure can cause a violent explosion or fire
• CAir and oxygen molecules are too large to escape through small leaks
• DOxygen will turn the copper piping into brittle brass alloy

What safety mechanism is built into a refrigerant recovery cylinder valve assembly to prevent the cylinder from exploding due to extreme pressure?

• AA manual handwheel lock
• BA pressure relief valve or rupture disk
• CA check valve that allows flow in one direction only
• DA mechanical pressure regulator

What is the correct first-aid action to take if liquid refrigerant splashes onto your bare skin and causes frostbite?

• ARub the affected skin vigorously with ice to freeze it back
• BApply direct heat using a blowtorch or boiling water
• CFlush the area immediately with lukewarm water and seek medical attention
• DCoat the area immediately with heavy motor oil or grease

What is the term for the heat energy absorbed or released when a substance changes its physical state without changing its temperature?

• ASensible heat
• BSuperheat
• CLatent heat
• DSubcooled heat

Which of the following describes 'sensible heat'?

• AHeat that causes a substance to change from a liquid to a vapor at constant temperature
• BHeat that causes a change in temperature of a substance that can be measured by a thermom…
• CThe heat required to melt ice into water at 0°C
• DHeat that changes the chemical composition of a refrigerant gas

In which component of the standard vapor compression cycle does the refrigerant undergo a drop in pressure, causing a portion of it to flash into vapor?

• AThe compressor
• BThe condenser
• CThe expansion device
• DThe evaporator

According to the Second Law of Thermodynamics, how does heat naturally flow between objects?

• AFrom a body of lower temperature to a body of higher temperature
• BFrom a body of higher temperature to a body of lower temperature
• COnly through vacuum spaces without any physical contact
• DEqually in both directions regardless of temperature differences

What is 'subcooling' in a refrigeration system?

• AThe cooling of liquid refrigerant below its saturation condensing temperature at a given…
• BThe boiling of liquid refrigerant inside the compressor crankcase
• CThe cooling of vapor refrigerant inside the evaporator coil below its freezing point
• DThe difference between the outdoor air temperature and the indoor air temperature

What is 'superheat' in a refrigeration system?

• AThe temperature of liquid refrigerant as it leaves the condenser
• BThe temperature of vapor refrigerant above its saturation boiling point at a given pressu…
• CThe excess heat generated by a compressor motor during an electrical overload
• DThe heat required to raise water to its boiling point at atmospheric pressure

What happens to the boiling point (saturation temperature) of a refrigerant when its pressure is increased?

• AThe boiling point decreases
• BThe boiling point increases
• CThe boiling point remains exactly the same
• DThe boiling point drops to absolute zero

What are the three physical modes of heat transfer?

• AEvaporation, condensation, and expansion
• BConduction, convection, and radiation
• CCompression, subcooling, and superheating
• DFriction, induction, and combustion

In a vapor compression refrigeration cycle, what is the primary function of the condenser?

• ATo absorb heat from the indoor air to boil liquid refrigerant
• BTo reject heat from the high-pressure refrigerant vapor, changing it into a liquid
• CTo pump refrigerant liquid directly to the compressor inlet
• DTo drop the pressure of the refrigerant before it enters the evaporator

In a vapor compression refrigeration cycle, what is the primary function of the evaporator?

• ATo reject heat from the system to the outdoor air
• BTo absorb heat from the space being cooled, causing the low-pressure liquid refrigerant t…
• CTo compress low-pressure vapor into a high-pressure liquid
• DTo filter oil and moisture out of the refrigerant before the expansion valve

What is the physical state and pressure condition of the refrigerant as it enters the compressor suction port?

• AHigh-pressure, subcooled liquid
• BLow-pressure, superheated vapor
• CHigh-pressure, superheated vapor
• DLow-pressure, saturated liquid

What is the physical state and pressure condition of the refrigerant as it leaves the compressor discharge port?

• ALow-pressure, superheated vapor
• BHigh-pressure, superheated vapor
• CLow-pressure, saturated liquid
• DHigh-pressure, subcooled liquid

Why is superheat measured and maintained at the evaporator outlet of a refrigeration system?

• ATo ensure that liquid refrigerant does not enter and damage the compressor
• BTo maximize the amount of liquid refrigerant stored in the evaporator coil
• CTo prevent the condenser from overheating during operation
• DTo reduce the pressure drop across the filter drier

A cooling capacity of 'One Ton of Refrigeration' is equivalent to the removal of how much heat energy per hour?

• A1,200 British Thermal Units (BTU) per hour
• B12,000 British Thermal Units (BTU) per hour
• C120,000 British Thermal Units (BTU) per hour
• D2,000 British Thermal Units (BTU) per hour

Which fundamental law of physics states that energy cannot be created or destroyed, only transformed from one form to another?

• AThe Zeroth Law of Thermodynamics
• BThe First Law of Thermodynamics (Law of Conservation of Energy)
• CThe Second Law of Thermodynamics
• DBoyle's Law

What is the primary function of the compressor in a vapor compression refrigeration system?

• ATo convert liquid refrigerant into solid ice
• BTo circulate refrigerant, raise its pressure, and raise its temperature to enable heat re…
• CTo drop the pressure of liquid refrigerant so it can boil in the condenser
• DTo separate oil from water inside the suction line accumulator

Which type of compressor compresses refrigerant vapor using a piston that moves back and forth within a cylinder?

• ARotary compressor
• BScroll compressor
• CReciprocating compressor
• DCentrifugal compressor

What is the primary thermodynamic process that occurs to the refrigerant inside the condenser?

• AThe refrigerant absorbs sensible heat and boils into a vapor
• BThe refrigerant releases latent heat to the surrounding medium and condenses into a liquid
• CThe refrigerant undergoes a severe drop in pressure and freezes solid
• DThe refrigerant is superheated by the outdoor fan motor

What is the primary thermodynamic process that occurs to the refrigerant inside the evaporator?

• AThe refrigerant absorbs heat from the space being cooled and boils into a vapor
• BThe refrigerant rejects heat to the indoor air, condensing into a subcooled liquid
• CThe refrigerant undergoes a temperature increase due to high pressure from the discharge…
• DThe refrigerant mixes with compressor oil to form a high-pressure gas

What are the two primary functions of a system's expansion (metering) device?

• ATo increase the pressure of the refrigerant and filter out moisture
• BTo drop the pressure of the liquid refrigerant and control the flow of refrigerant into t…
• CTo separate oil from the gas and heat the compressor shell
• DTo cycle the fan motor on and off based on high-pressure limits

Which type of metering device utilizes a sensing bulb filled with refrigerant to adjust the flow rate based on evaporator superheat?

• ACapillary tube
• BAutomatic expansion valve (AXV)
• CThermostatic expansion valve (TXV)
• DOrifice plate

What is a capillary tube metering device?

• AA complex electrical valve driven by a stepper motor
• BA long, narrow copper tube of fixed length and internal diameter that restricts refrigera…
• CA valve that regulates pressure using a pneumatic control line
• DA type of filter drier containing activated alumina beads

What component is installed in the liquid line directly before the expansion device to remove contaminants, acids, and water?

• ASuction line accumulator
• BLiquid line filter drier
• COil separator
• DMuffler

What is the primary function of a suction line accumulator in a low-temperature refrigeration system?

• ATo store high-pressure liquid refrigerant leaving the condenser
• BTo temporarily trap any liquid refrigerant and allow only vapor to enter the compressor s…
• CTo cool down the compressor discharge gas before it enters the condenser
• DTo separate nitrogen from refrigerant during commissioning

Which type of compressor utilizes one stationary spiral scroll and one orbiting spiral scroll to compress refrigerant vapor?

• AReciprocating compressor
• BScrew compressor
• CScroll compressor
• DCentrifugal compressor

What is the purpose of the crankcase heater installed on a refrigeration compressor?

• ATo heat the building space during cold winter months
• BTo keep the compressor oil warm during the off-cycle to prevent refrigerant migration and…
• CTo superheat the refrigerant vapor inside the cylinder during the compression stroke
• DTo preheat the cooling fan motor before starting

Which component is used in a system pump-down cycle to stop the flow of liquid refrigerant to the expansion valve when the thermostat is satisfied?

• AA liquid line solenoid valve
• BA high-pressure bypass valve
• CA mechanical pressure regulator
• DA service manifold gauge

What is an Automatic Expansion Valve (AXV) designed to maintain constant?

• AConstant evaporator superheat
• BConstant condenser subcooling
• CConstant evaporator pressure
• DConstant compressor motor speed

Which type of condenser uses a fan to pull or push ambient air across a coil consisting of copper tubes and aluminum fins?

• ANatural draft air-cooled condenser
• BForced-draft or induced-draft air-cooled condenser
• CTube-in-tube water-cooled condenser
• DEvaporative condenser

Where is the liquid receiver typically located in a refrigeration system?

• AIn the suction line directly before the compressor
• BIn the liquid line directly after the condenser
• CIn the discharge line before the oil separator
• DInside the evaporator coil assembly

What does the presence of continuous bubbles in a liquid line sight glass typically indicate?

• AThe system is operating at maximum refrigerant charge and efficiency
• BThe system is undercharged or there is a restriction in the liquid line
• CThe compressor oil level is too high
• DThe expansion valve is fully closed

Which type of compressor uses high-speed rotating impellers to throw refrigerant vapor outward, raising pressure through kinetic energy?

• AScroll compressor
• BScrew compressor
• CCentrifugal compressor
• DReciprocating compressor