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Odisha CHSE +2 VOC Field Technician Air Conditioner study materials
Odisha CHSE +2 VOC Field Technician Air Conditioner study resources

Odisha CHSE +2 VOC Field Technician Air Conditioner practice questions

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Question 1Fundamentals of Refrigeration and Air Conditioning

In a vapour-compression refrigeration cycle, what is the primary function of the compressor?

  1. To raise the pressure and temperature of the refrigerant vapour so it can be condensed Correct answer.
  2. To remove heat from the refrigerated space directly
  3. To reduce the refrigerant pressure before the evaporator
  4. To filter moisture and dirt from the refrigerant liquid

Explanation

The compressor draws low-pressure vapour from the evaporator and compresses it to a higher pressure, which also raises its saturation temperature so that heat can be rejected to ambient air in the condenser. It does not itself absorb heat from the room; that is the evaporator's job.

Question 2Fundamentals of Refrigeration and Air Conditioning

Which component of a window air conditioner rejects heat from the refrigerant to the outside air?

  1. The capillary tube
  2. The condenser coil Correct answer.
  3. The accumulator
  4. The evaporator coil

Explanation

The condenser is the heat-rejection coil; inside it hot high-pressure vapour gives up heat to the outdoor air and condenses to liquid. The evaporator does the opposite, absorbing heat from the room air.

Question 3Fundamentals of Refrigeration and Air Conditioning

A technician measures the suction line of a running split AC and finds it warm rather than cold. Which condition does this most directly suggest?

  1. Thermostat set point reached
  2. Correct superheat with normal operation
  3. Condenser fan motor failure
  4. Refrigerant undercharge or a restriction reducing evaporator feed Correct answer.

Explanation

A properly fed evaporator produces a cold, sweating suction line because low-pressure saturated vapour is returning. A warm suction line indicates little or no liquid refrigerant is evaporating, typical of undercharge or a restriction such as a blocked capillary or strainer.

Question 4Fundamentals of Refrigeration and Air Conditioning

What is the purpose of superheat in a refrigeration system?

  1. To raise the evaporating pressure above atmospheric
  2. To reduce the compressor discharge temperature
  3. To increase the cooling capacity of the condenser
  4. To ensure no liquid refrigerant reaches the compressor Correct answer.

Explanation

Superheat is the temperature of vapour above its saturation temperature. A small controlled amount at the evaporator outlet guarantees the refrigerant is fully vaporised, protecting the compressor from liquid slugging.

Question 5Fundamentals of Refrigeration and Air Conditioning

Which refrigerant is classified as an HFC and has zero ozone depletion potential?

  1. R-134a Correct answer.
  2. R-22
  3. R-12
  4. R-717 (ammonia)

Explanation

R-134a is a hydrofluorocarbon containing no chlorine, so its ozone depletion potential is zero. R-22 and R-12 are HCFC and CFC respectively, both of which contain chlorine and deplete ozone.

Question 6Fundamentals of Refrigeration and Air Conditioning

In a reciprocating compressor, what is the effect of too much oil being carried over into the refrigerant circuit?

  1. It raises the evaporating temperature
  2. It improves lubrication of the expansion valve
  3. It coats evaporator walls and reduces heat transfer Correct answer.
  4. It increases the compressor volumetric efficiency

Explanation

Oil that circulates excessively forms a film on the inside of the evaporator tubes, adding a thermal resistance that reduces heat transfer and lowers capacity. It also risks oil logging and compressor damage from oil starvation in the crankcase.

Question 7Fundamentals of Refrigeration and Air Conditioning

What does a reading of 30 percent relative humidity in a conditioned room indicate?

  1. The room contains 30 percent water by mass
  2. The air holds 30 percent of the water vapour it could hold at that temperature Correct answer.
  3. The air is 30 percent saturated with dry air
  4. The dew point is 30 degrees Celsius

Explanation

Relative humidity is the ratio of actual water vapour pressure to the saturation vapour pressure at the same dry-bulb temperature, expressed as a percentage. It therefore describes how close the air is to saturation, not an absolute moisture quantity.

Question 8Fundamentals of Refrigeration and Air Conditioning

Which instrument is used to measure the dry-bulb and wet-bulb temperatures for psychrometric calculations?

  1. Sling psychrometer Correct answer.
  2. Clamp meter
  3. Vacuum micron gauge
  4. Manifold gauge set

Explanation

A sling psychrometer uses two thermometers, one with a wetted wick, and the difference between dry-bulb and wet-bulb readings gives the relative humidity from a psychrometric chart. Manifold gauges read refrigerant pressure, not air temperature.

Question 9Fundamentals of Refrigeration and Air Conditioning

A split AC has normal suction pressure but the evaporator coil is only partially cold. What is the most likely cause?

  1. Compressor valve failure
  2. Capillary tube completely blocked
  3. Overcharge of refrigerant
  4. Blocked or dirty air filter reducing airflow Correct answer.

Explanation

Restricted airflow from a clogged filter means less heat is transferred to the coil, so only part of the evaporator appears cold while suction pressure can remain near normal. Cleaning or replacing the filter restores uniform coil temperature.

Question 10Fundamentals of Refrigeration and Air Conditioning

What is the function of the capillary tube in a small room air conditioner?

  1. To dry the refrigerant
  2. To store liquid refrigerant
  3. To separate oil from refrigerant vapour
  4. To throttle high-pressure liquid to low pressure and control flow Correct answer.

Explanation

The capillary tube is a fixed restriction that drops the pressure of liquid refrigerant from condensing pressure to evaporating pressure and meters the flow. It has no moving parts, so flow varies with load.

Question 11Fundamentals of Refrigeration and Air Conditioning

Which type of expansion valve adjusts its opening automatically in response to the superheat at the evaporator outlet?

  1. Automatic expansion valve
  2. Capillary tube
  3. Hand shut-off valve
  4. Thermostatic expansion valve Correct answer.

Explanation

A thermostatic expansion valve senses evaporator outlet temperature and pressure with a bulb and modulates the orifice to maintain a set superheat. An automatic expansion valve instead holds constant evaporator pressure regardless of superheat.

Question 12Fundamentals of Refrigeration and Air Conditioning

In a refrigeration system, what does subcooling of the liquid leaving the condenser indicate?

  1. The liquid is colder than its saturation temperature for that pressure Correct answer.
  2. The condenser is flooded with oil
  3. The refrigerant is boiling in the receiver
  4. The liquid has partially vaporised

Explanation

Subcooling is the number of degrees the liquid is below the saturation temperature corresponding to its pressure. It confirms the condenser is removing heat effectively and that the liquid seal at the expansion device is sound.

Question 13Fundamentals of Refrigeration and Air Conditioning

A window AC is cooling poorly and the compressor runs continuously. The condenser coil is covered with dust and lint. What is the expected effect on head pressure and current draw?

  1. Head pressure rises and current draw increases Correct answer.
  2. Head pressure falls and current draw decreases
  3. Head pressure rises but current draw is unaffected
  4. Head pressure and current draw both fall

Explanation

A fouled condenser cannot reject heat, so discharge pressure climbs. Higher head pressure means the compressor works against a greater pressure difference, raising current draw and risking overload tripping. Cleaning the coil restores normal pressures.

Question 14Fundamentals of Refrigeration and Air Conditioning

Which of the following best describes the sensible cooling process in an air-conditioned room?

  1. Moisture is added to the air while temperature stays constant
  2. Water vapour condenses on the coil and removes latent heat
  3. Air temperature drops without a change in moisture content Correct answer.
  4. Air temperature rises while humidity falls

Explanation

Sensible cooling lowers the dry-bulb temperature of the air without changing its moisture content, so no latent heat is removed. Latent cooling, in contrast, involves condensation of water vapour on the coil.

Question 15Fundamentals of Refrigeration and Air Conditioning

What is the main reason for evacuating a refrigeration system with a vacuum pump before charging?

  1. To remove moisture and non-condensable gases Correct answer.
  2. To cool the compressor windings
  3. To test the compressor valves
  4. To increase the refrigerant charge

Explanation

Evacuation lowers the boiling point of water so that trapped moisture vaporises and is drawn out, and it also removes air and other non-condensables. Non-condensables raise head pressure and reduce capacity.

Question 16Fundamentals of Refrigeration and Air Conditioning

A technician reads a low-side gauge of 4.5 bar with R-22 at the evaporator. If the corresponding saturation temperature is about 5 degrees Celsius and the suction line is at 12 degrees Celsius, what is the superheat?

  1. 7 K Correct answer.
  2. 3 K
  3. 17 K
  4. 12 K

Explanation

Superheat is the suction line temperature minus the saturation temperature at the same pressure. Here 12 minus 5 equals 7 K, which is a typical target superheat for a small comfort-cooling system.

Question 17Fundamentals of Refrigeration and Air Conditioning

In a hermetic compressor, what does the term 'hermetic' refer to?

  1. The compressor is driven by an external belt
  2. The compressor and motor are sealed in a single welded shell Correct answer.
  3. The compressor is open to the atmosphere
  4. The compressor uses no lubricating oil

Explanation

A hermetic compressor has the motor and compressor enclosed in a welded gastight shell with no shaft seal, so refrigerant and oil are fully contained. This reduces leakage but makes internal repair impossible, requiring replacement instead.

Question 18Fundamentals of Refrigeration and Air Conditioning

Why is R-410A charged as a liquid rather than as a vapour?

  1. It is a near-azeotropic blend whose components could fractionate Correct answer.
  2. It is flammable as a gas
  3. It contains lubricating oil
  4. It has a very low boiling point

Explanation

R-410A is a blend of R-32 and R-125 that can separate if vapour is drawn from a cylinder, changing the composition and performance. Charging as liquid from the cylinder keeps the mixture uniform.

Question 19Fundamentals of Refrigeration and Air Conditioning

What is the purpose of a filter-drier in a refrigeration circuit?

  1. To trap moisture and solid contaminants in the liquid line Correct answer.
  2. To store excess refrigerant during low load
  3. To reduce compressor noise
  4. To regulate evaporator pressure

Explanation

A filter-drier contains a desiccant and screen that remove water and particulate matter from the refrigerant, preventing ice blockage and wear. It is normally installed in the liquid line ahead of the expansion device.

Question 20Fundamentals of Refrigeration and Air Conditioning

A technician finds frost forming only at the inlet of the evaporator and suction pressure below normal. Which fault best fits?

  1. Restriction in the liquid line or capillary tube Correct answer.
  2. Overcharge of refrigerant
  3. Condenser fan running too fast
  4. Thermostat bulb loose on the suction line

Explanation

A restriction starves the evaporator, so refrigerant flashes immediately after the metering device and frost appears at the coil inlet while suction pressure falls. The fix is to locate and clear the restriction or replace the blocked drier.

Question 21Fundamentals of Refrigeration and Air Conditioning

Which safety precaution applies when handling refrigerant cylinders in the workshop?

  1. Lay cylinders horizontally for easier charging
  2. Fill cylinders completely to avoid air entry
  3. Store cylinders in direct sunlight to keep them warm
  4. Keep cylinders upright, capped and away from heat sources Correct answer.

Explanation

Refrigerant cylinders must be kept upright, valve-capped and away from heat, because heating raises pressure and can rupture the cylinder. They should also never be overfilled, since liquid expansion with temperature rise leaves no room for safety.

Question 22Fundamentals of Refrigeration and Air Conditioning

What does a low-side pressure that is higher than normal together with a frosted suction line usually indicate?

  1. Undercharge of refrigerant
  2. Overcharge or a stuck-open expansion valve causing flooding Correct answer.
  3. A completely blocked filter-drier
  4. A faulty condenser fan

Explanation

Excess liquid refrigerant reaching the evaporator raises suction pressure and can frost the suction line because the coil is flooded. This points to overcharge or an expansion valve stuck open, allowing too much refrigerant through.

Question 23Fundamentals of Refrigeration and Air Conditioning

What is the standard unit for expressing the cooling capacity of a small room air conditioner in India?

  1. Pascal
  2. Cubic metre per second
  3. Kilowatt-hour
  4. Ton of refrigeration Correct answer.

Explanation

Cooling capacity is commonly stated in tons of refrigeration, where one ton equals 3.517 kW of heat removal. Kilowatt-hour measures energy, pascal measures pressure, and cubic metres per second measures airflow.

Question 24Fundamentals of Refrigeration and Air Conditioning

In a direct expansion (DX) split air conditioner, where does the refrigerant change from liquid to vapour?

  1. In the evaporator coil Correct answer.
  2. In the compressor cylinder
  3. In the condenser coil
  4. In the liquid receiver

Explanation

In a DX system the refrigerant is metered into the evaporator coil, where it boils and absorbs heat from the room air, changing from liquid to vapour. The condenser performs the reverse change.

Question 25Fundamentals of Refrigeration and Air Conditioning

A technician wants to check whether a room AC is correctly charged without opening the circuit. Which combination of measurements is most informative?

  1. Room thermostat setting only
  2. Condenser coil size only
  3. Compressor current alone
  4. Suction pressure, suction line temperature and outdoor ambient temperature Correct answer.

Explanation

Superheat calculated from suction pressure and suction line temperature, together with ambient temperature, tells the technician whether the evaporator is properly fed. Current alone cannot distinguish undercharge from other faults.

Question 26Fundamentals of Refrigeration and Air Conditioning

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

  1. To remove moisture and dirt from the circulating refrigerant
  2. To absorb heat from the room air and lower its temperature
  3. To reject heat from the high-pressure refrigerant vapour so that it condenses into liquid Correct answer.
  4. To reduce the refrigerant pressure before it enters the evaporator

Explanation

The condenser receives hot high-pressure vapour from the compressor and rejects its latent heat to the surrounding air or water, so the refrigerant changes phase to liquid. This heat rejection is what allows the cycle to balance the heat absorbed in the evaporator. Pressure reduction is the expansion device's job, not the condenser's.

Question 27Fundamentals of Refrigeration and Air Conditioning

A technician measures a room's dry-bulb temperature as 30 degrees C and its wet-bulb temperature as 22 degrees C. What does the difference between these two readings indicate?

  1. The moisture content and drying potential of the air Correct answer.
  2. The total cooling capacity of the air conditioner
  3. The evaporator superheat of the system
  4. The saturation pressure of the refrigerant

Explanation

The wet-bulb depression, the gap between dry-bulb and wet-bulb readings, shows how much moisture the air can still take up through evaporation. A large depression means dry air with good evaporative cooling potential; a small depression means humid air close to saturation. Superheat, refrigerant pressure and capacity are separate system measurements.

Question 28Fundamentals of Refrigeration and Air Conditioning

Why is the suction line of a correctly operating room air conditioner normally insulated?

  1. To stop the refrigerant from freezing inside the suction line
  2. To protect the copper tube from corrosion by room air
  3. To keep the suction pressure from rising above design limits
  4. To prevent the cold vapour from absorbing heat before it reaches the compressor Correct answer.

Explanation

The suction line carries cold low-pressure vapour from the evaporator to the compressor. Insulation limits heat gain from the warm room, which keeps superheat within design limits and prevents liquid carry-over and loss of capacity. Freezing and pressure control are not the purpose of this insulation.

Question 29Fundamentals of Refrigeration and Air Conditioning

A split air conditioner with a thermostatic expansion valve shows very low suction pressure, a starved evaporator and almost no frost. The valve sensing bulb has lost its charge. What is the most likely effect on the valve?

  1. The valve stays nearly closed and restricts refrigerant flow Correct answer.
  2. The valve stays wide open and floods the evaporator
  3. The valve opens and closes rapidly without affecting flow
  4. The valve reverses the refrigerant flow direction

Explanation

A lost bulb charge removes the closing force on the valve diaphragm, but the spring and evaporator pressure then hold the valve near its minimum opening. The evaporator is starved of refrigerant, so suction pressure falls and little cooling occurs. A flooded evaporator would instead point to an overfeeding valve.

Question 30Fundamentals of Refrigeration and Air Conditioning

Which property of a refrigerant mainly determines whether it can be used with a given compressor lubricating oil without separation?

  1. Its ozone depletion potential
  2. Its miscibility with the oil Correct answer.
  3. Its dielectric strength
  4. Its specific heat ratio

Explanation

Miscibility describes how well the refrigerant mixes with the compressor oil and is carried around the circuit to return oil to the compressor. Poor miscibility can leave oil trapped in the evaporator and starve the compressor of lubrication. Ozone depletion, specific heat ratio and dielectric strength affect other selection criteria.

Question 31Refrigerants, Ozone Depletion and Safety

Under the Montreal Protocol phase-out schedule, which group of refrigerants is being eliminated because of its high ozone depletion potential?

  1. Natural refrigerants such as ammonia
  2. Hydrocarbons such as isobutane
  3. Hydrofluorocarbons such as R-134a
  4. Hydrochlorofluorocarbons such as R-22 Correct answer.

Explanation

HCFCs such as R-22 contain chlorine and have a measurable ozone depletion potential, so the Montreal Protocol schedules their phase-out. HFCs contain no chlorine and are controlled instead under the Kigali Amendment for global warming, not ozone depletion.

Question 32Refrigerants, Ozone Depletion and Safety

A technician must identify the refrigerant in a recovered cylinder before storage. Which property is the most reliable reason for never using the smell of the gas as the identifier?

  1. Refrigerant smell disappears below 10 degrees Celsius
  2. Only reclaimed refrigerant has a detectable smell
  3. Refrigerant odour changes with cylinder pressure
  4. Many refrigerants are odourless or only odorised for leak detection Correct answer.

Explanation

Most common refrigerants are odourless in pure form, and the distinctive smell added to some blends comes from an odorant for leak detection, not from the refrigerant itself. Smell therefore cannot confirm identity, and only proper labelling and analysis can.

Question 33Refrigerants, Ozone Depletion and Safety

Which safety hazard is specific to handling refrigerant cylinders that are exposed to a fire or direct sun?

  1. The oil inside turns into a solid wax
  2. The cylinder may rupture from pressure rise as the liquid expands and vaporises Correct answer.
  3. The refrigerant freezes and blocks the valve
  4. The cylinder becomes lighter and floats

Explanation

A sealed cylinder filled with liquid refrigerant can develop very high pressure when heated because liquid expansion and vaporisation leave no room for relief. Cylinders must be stored shaded, upright and below their rated temperature, away from heat sources.

Question 34Refrigerants, Ozone Depletion and Safety

Why must a refrigerant cylinder valve be opened slowly and the cylinder kept upright when charging liquid refrigerant?

  1. To prevent liquid slugging that can damage the compressor Correct answer.
  2. To reduce the sound of the gas flow
  3. To avoid drawing moisture from the air into the hose
  4. To keep the cylinder label readable

Explanation

Charging liquid too quickly or in the wrong state can send liquid refrigerant into the compressor suction, causing slugging and mechanical damage. Keeping the cylinder upright and throttling the valve controls the flow and protects the compressor.

Question 35Refrigerants, Ozone Depletion and Safety

What does an ozone depletion potential value of zero mean for a refrigerant such as R-410A?

  1. The refrigerant contains no chlorine or bromine that can reach the stratosphere Correct answer.
  2. The refrigerant cannot leak from a system
  3. The refrigerant has no global warming effect
  4. The refrigerant is safe to vent to atmosphere

Explanation

Ozone depletion potential measures the ability of a substance to release ozone-destroying chlorine or bromine in the stratosphere. A zero value means the molecule contains no such halogen, but it says nothing about flammability, toxicity or global warming.

Question 36Refrigerants, Ozone Depletion and Safety

Which personal protective equipment is essential when a technician purges or opens a system containing R-22 liquid?

  1. No protection if the room is ventilated
  2. A dust mask and sandals
  3. Safety goggles and insulating gloves Correct answer.
  4. Only a cotton apron

Explanation

Liquid refrigerant at its boiling point can cause severe cold burns and eye injury on contact, so goggles and low-temperature gloves are required. Ventilation protects against asphyxiation but does not prevent contact frostbite.

Question 37Refrigerants, Ozone Depletion and Safety

A recovery cylinder is labelled with a tare weight of 10 kg and a capacity limit of 12 kg of refrigerant. It currently weighs 19 kg. What is the maximum additional refrigerant that may be charged into it?

  1. 3 kg Correct answer.
  2. 1 kg
  3. 12 kg
  4. 9 kg

Explanation

The refrigerant present is 19 kg gross minus 10 kg tare, which equals 9 kg. The remaining allowance is the 12 kg limit minus 9 kg, giving 3 kg, and filling beyond this risks hydraulic rupture.

Question 38Refrigerants, Ozone Depletion and Safety

Why is nitrogen used for pressure testing and leak checking of a refrigerant circuit rather than oxygen?

  1. Nitrogen changes colour when a leak occurs
  2. Oxygen can combine explosively with compressor oil under pressure Correct answer.
  3. Oxygen has a higher ozone depletion potential
  4. Nitrogen is cheaper than refrigerant and oxygen

Explanation

Oxygen under pressure reacts violently with lubricating oil and can cause fire or explosion inside the circuit. Dry nitrogen is inert, inexpensive and leaves no residue, making it the standard test gas.

Question 39Refrigerants, Ozone Depletion and Safety

A technician is asked to retrofit an R-22 system to an HFC refrigerant. Which step is most important before charging the new refrigerant?

  1. Remove the filter drier permanently
  2. Increase the compressor speed setting
  3. Seal all service ports with tape
  4. Confirm the new refrigerant is compatible with the existing oil and seals Correct answer.

Explanation

R-22 uses mineral oil while most HFC replacements need polyolester oil, and elastomer seals may swell or shrink differently. Compatibility checks and usually an oil change or additive are required before charging to avoid sludge and leaks.

Question 40Refrigerants, Ozone Depletion and Safety

During evacuation of a system, a technician notices the vacuum gauge stalls at a high reading and rises when the pump is isolated. What is the most likely cause?

  1. The gauge is reading in psig instead of microns
  2. The system is fully dehydrated
  3. The vacuum pump oil is brand new
  4. There is a leak or moisture in the circuit Correct answer.

Explanation

A vacuum that rises after isolation indicates air or moisture entering or outgassing from the system, typically from a leak or trapped moisture. A tight, dry system holds its vacuum when the pump is valved off.

Question 41Refrigerants, Ozone Depletion and Safety

Why does the Montreal Protocol control HCFC production even though HCFCs have much lower ozone depletion potential than CFCs?

  1. HCFCs still release chlorine in the stratosphere and are used in large quantities Correct answer.
  2. HCFCs have a higher global warming potential than all other gases
  3. HCFCs are more toxic than CFCs
  4. HCFCs are flammable and cannot be stored

Explanation

ODP is a per-molecule measure, but the total chlorine reaching the stratosphere depends on how much gas is emitted. HCFCs are widely used and still carry chlorine, so their aggregate effect justifies a scheduled phase-out.

Question 42Refrigerants, Ozone Depletion and Safety

A recovery machine is connected to a system containing a blend such as R-404A. Why should the refrigerant not be recovered into a cylinder that already holds a different refrigerant?

  1. Mixing creates an unidentifiable mixture that cannot be reclaimed Correct answer.
  2. The cylinder will lose its paint
  3. The recovery machine will run faster
  4. The blend will turn into a pure azeotrope

Explanation

Recovered refrigerant must be identifiable for reclamation or destruction, and mixing different refrigerants makes the batch unusable and potentially unsafe. Each cylinder should hold a single, documented refrigerant.

Question 43Refrigerants, Ozone Depletion and Safety

Which property of ammonia makes it a suitable refrigerant but also demands specific safety measures in a plant room?

  1. It destroys the ozone layer rapidly
  2. It is highly toxic and irritant to eyes and airways at low concentrations Correct answer.
  3. It is flammable only above 500 degrees Celsius
  4. It is heavier than air and collects in pits

Explanation

Ammonia has excellent thermodynamic properties and zero ozone depletion potential, but it is toxic and irritant, so leak detection, ventilation and escape routes are essential. Being lighter than air, it disperses upward rather than pooling in pits.

Question 44Refrigerants, Ozone Depletion and Safety

A technician finds a frost pattern on the suction line of a system charged with R-22 and suspects overcharging. Which additional observation best supports a diagnosis of overcharge rather than undercharge?

  1. Low suction pressure with high superheat
  2. High discharge pressure with high subcooling at the condenser outlet Correct answer.
  3. Compressor short-cycling with no pressure change
  4. Very low head pressure and bubbling in the sight glass

Explanation

Excess refrigerant raises the condensing pressure and leaves more liquid subcooled at the condenser outlet. Undercharge shows the opposite pattern of low head pressure, bubbles and high superheat.

Question 45Refrigerants, Ozone Depletion and Safety

Why is it unsafe to use a refrigerant cylinder as a support or to roll it on its side during transport?

  1. The cylinder loses its tare weight marking
  2. It reduces the global warming potential of the gas
  3. Valve damage or liquid carry-over can cause a violent release Correct answer.
  4. The refrigerant changes into a different chemical

Explanation

Cylinders are designed for upright handling, and a damaged valve or liquid entering the regulator can produce a sudden, forceful release. Transport rules require cylinders secured upright with valve caps fitted.

Question 46Refrigerants, Ozone Depletion and Safety

A technician must dispose of a small amount of recovered R-134a that cannot be reclaimed. Which action complies with good environmental practice?

  1. Return it to a certified reclamation or destruction facility Correct answer.
  2. Burn it in an open container
  3. Pour it into the drain with water
  4. Vent it slowly outdoors so it disperses

Explanation

R-134a is a potent greenhouse gas and must not be released to the atmosphere; recovered refrigerant is sent to a certified reclaimer or destroyed under controlled conditions. Venting, draining or open burning all release the gas or its breakdown products.

Question 47Refrigerants, Ozone Depletion and Safety

Two cylinders of the same size contain R-22 and R-134a at the same room temperature. Why can the saturation pressures differ significantly even though both are stored identically?

  1. Only the colour of the cylinder affects pressure
  2. Cylinder size determines pressure
  3. Saturation pressure depends on the refrigerant's own vapour pressure curve Correct answer.
  4. Pressure depends on the age of the cylinder

Explanation

At a given temperature each refrigerant has its own saturation pressure determined by its thermodynamic properties. R-22 and R-134a therefore read differently on a gauge at the same ambient temperature, which is why pressure alone never identifies a refrigerant.

Question 48Refrigerants, Ozone Depletion and Safety

A recovery cylinder contains a zeotropic blend that has partially leaked as a gas. Why must the remaining liquid not be topped up and used as if it were the original blend?

  1. The cylinder has lost its certification
  2. The gas has turned into a CFC
  3. The components have fractionated, so the remaining liquid has a different composition Correct answer.
  4. The pressure rating of the cylinder has increased

Explanation

In a zeotropic blend the components have different volatilities, so a vapour leak removes a disproportionate share of the more volatile component. The remaining liquid no longer matches the original composition, and its performance and safety data no longer apply.

Question 49Refrigerants, Ozone Depletion and Safety

A plant room uses a large ammonia system. Which combination of design features best addresses the toxic hazard in the event of a major leak?

  1. A single handheld torch for inspection
  2. A gas detector linked to an alarm plus mechanical ventilation and marked escape routes Correct answer.
  3. Sealing the room completely with no ventilation
  4. Storing ammonia cylinders next to the plant

Explanation

Toxic gas control relies on early detection, automatic ventilation and clear escape routes so occupants can leave before exposure becomes dangerous. Sealing the room or relying on manual inspection would worsen the outcome.

Question 50Refrigerants, Ozone Depletion and Safety

A technician compares two candidate replacements for an R-22 system: one with ODP 0 and GWP 2088, another with ODP 0 and GWP 631. Both meet the cooling capacity requirement. Which reasoning best reflects a balanced environmental and regulatory decision?

  1. Choose the lower-GWP option while verifying safety, oil compatibility and legal limits Correct answer.
  2. Choose the higher-GWP option because it is always cheaper
  3. Choose either option because both have zero ODP
  4. Choose the higher-GWP option because GWP does not matter

Explanation

With ozone depletion addressed by both candidates, the decision shifts to global warming impact, so the lower-GWP refrigerant is preferred, subject to confirming safety, lubricant compatibility and any national phase-down limits. Zero ODP alone no longer distinguishes the options.