Testy

F-Gas English Low GWP

Všetky otázky
HFC | Flammable | CO₂ | NH₃
Ľahké otázky | Stredne ťažké otázky | Ťažké otázky

1

Ľahká

What is the base unit of mass in the International System of Units (SI)?


N
lb (pound)
t
kg

2

Stredne ťažká

What process takes place in the condenser of a refrigeration system?


Hot vapour discharged by the compressor is desuperheated, condensed, and the resulting liquid is slightly subcooled
The refrigerant absorbs heat from the surroundings and evaporates
The secondary fluid (glycol, water) condenses while the refrigerant evaporates
The refrigerant rejects only the heat generated in the compressor

3

Stredne ťažká

What mainly determines the condensing temperature of an air-cooled condenser?


The superheat
The ambient (inlet) air temperature
The evaporating temperature
The compressor discharge temperature

4

Stredne ťažká

Why does heat flow from the condenser to the surroundings?


Because the compressor pushes heat directly into the surroundings
Because the condensing temperature is higher than the ambient temperature, and heat flows spontaneously from a warmer to a colder body (second law of thermodynamics)
Because HFC refrigerants attract heat from the surroundings
Because the pressure in the condenser is lower than ambient

5

Stredne ťažká

What should you mainly pay attention to when operating a condenser?


Its general condition and the cleanliness of the heat-exchange surfaces
The colour of the condenser casing
That the outlet air temperature is higher than the condensing temperature
That the inlet air temperature is lower than the outlet air temperature

6

Stredne ťažká

What criteria should be considered when selecting a suitable condenser?


Only own experience and the dimensions
Only the size and number of fans
Fan noise, connection diameters and colour
The required capacity of the condenser and the technical specifications declared by the manufacturer

7

Stredne ťažká

How do contaminants (dust, particulates, deposits) affect the performance and efficiency of heat exchange surfaces in condensers?


Contaminants do not significantly affect the efficiency and effectiveness of the heat exchange surfaces in condensers.
Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause a reduction in condensing pressure.
Contaminants increase the heat transfer area and reduce the condensing pressure.
Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause an increase in condensing temperature and pressure, which in turn leads to a reduction in the condenser’s efficiency.

8

Stredne ťažká

How does the capacity of an air-cooled condenser change when it becomes dirty?


It increases because the fan speed rises
It increases
It decreases
It remains unchanged

9

Stredne ťažká

What is the main consequence of heavy frost on an air-cooling evaporator?


Reduced heat transfer and airflow, resulting in a drop in cooling capacity and evaporating temperature
A rise in the cooled-air temperature with no effect on capacity
An increase in condenser subcooling
A rise in evaporating pressure

10

Stredne ťažká

What happens when the evaporation temperature drops?


The compressor’s cooling capacity decreases.
The compressor’s cooling capacity increases.
The condenser fan speed increases.
The discharge temperature decreases.

11

Stredne ťažká

When is natural (off-cycle, air) defrosting possible?


Only in freezer rooms below −18 °C
Never – electric heaters must be used in every air cooler
Only in coolers fitted with speed-controlled fans
When the air passing through the cooler is above 0 °C

12

Stredne ťažká

When does frost form on the surface of an air-cooling evaporator?


Only when the system runs continuously
Only when the room air temperature falls below 0 °C
Always, in every air cooler
When the evaporator surface temperature is below 0 °C and below the dew point of the air

13

Stredne ťažká

In extensive pipework systems, flash gas (secondary evaporation) in the liquid line can be prevented by…


…using smaller-diameter pipes
…insulating the discharge line between the compressor and the condenser
…increasing the length of the liquid line
…additional subcooling of the liquid

14

Stredne ťažká

How does hot gas defrosting of the evaporator work?


We switch on the gas heater directed at the evaporator.
We swap the outlet and inlet sides of the evaporator.
This involves reversing the direction of rotation of the compressor.
Heated vapour (hot gas) from the compressor is directed into the evaporator piping.

15

Stredne ťažká

What is the function of the evaporator in a refrigeration system?


It transfers heat from the medium being cooled to the boiling refrigerant.
It ensures that the refrigerant is superheated over the largest possible heat exchange surface area.
It cools the refrigerant.
It evaporates the water flowing through the evaporator.

16

Stredne ťažká

What condition must electric heaters for evaporator defrosting meet?


They must be in direct contact with the refrigerant
Heat from the heaters must be carried by the running fans
They must be located beneath the evaporator
They must have good thermal contact with the heat-exchange surface (e.g. inserted in the fin block)

17

Stredne ťažká

Refrigerant distributor:


acts as a buffer for the refrigerant in the event that the pressure upstream of the expansion valve is exceeded.
ensures an even distribution of the refrigerant to the individual sections of the evaporator.
ensures even distribution of the refrigerant to the individual sections of the condenser.
ensures the even distribution of the refrigerant discharged by compressors connected in parallel.

18

Stredne ťažká

What defrosting methods are used for air coolers?


Only by switching off the fans with the compressor running
Electric only – other methods are not permitted in refrigeration
Electric, hot gas, water spray and natural (at positive temperatures)
Natural only – other methods are ineffective and uneconomic

19

Stredne ťažká

The boiling point of a liquid rises when the pressure above the liquid…


…rises
…remains constant
…varies depending on the ambient temperature
…falls

20

Stredne ťažká

MOP in thermostatic expansion valves stands for:


maximum operating pressure.
minimum flow opening.
maximum pressure switch protection.
self-cleaning of the valve in the event of moisture in the refrigerant freezing.

21

Stredne ťažká

The function of a thermostatic expansion valve (TEV) is:


to maintain a constant condensing pressure
to maintain a constant compressor suction pressure
to adjust the evaporating pressure in the condenser
to meter refrigerant into the evaporator according to the superheat of the vapour leaving the evaporator

22

Stredne ťažká

What type of compressor motor can be used with a capillary tube?


A high-starting-torque motor must be used
A low-starting-torque motor (pressures equalise during standstill)
An electronically commutated motor
A low-speed motor

23

Stredne ťažká

What does a thermostatic expansion valve control?


The temperature in the cold room
The discharge temperature
The mass flow of refrigerant fed into the evaporator
The condensing pressure

24

Ľahká

The refrigerant absorbs heat when…


…it condenses
…it freezes
…it is subcooled
…it evaporates

25

Stredne ťažká

What does the manufacturer state as the factory setting of a thermostatic expansion valve?


the static superheat of the valve.
the superheat value during valve operation.
the degree of refrigerant expansion.
the degree to which the valve is filled with refrigerant liquid.

26

Stredne ťažká

Where is a new or repaired system with an expansion valve and liquid receiver charged?


In the liquid phase into the compressor suction, with the compressor running
Anywhere – the charging point does not matter
In the liquid phase on the high-pressure side, with the compressor stopped
Through the capillary tube outlet during normal system operation

27

Stredne ťažká

What does a thermostatic or electronic expansion valve control?


The amount of refrigerant fed to the evaporator according to superheat
Subcooling, by adjusting condensing pressure
The compressor speed
The evaporating pressure – closing below the set point

28

Stredne ťažká

What does the MOP function of thermostatic expansion valves mean?


The valve maintains a constant condensing pressure
The valve limits the maximum evaporating (suction) pressure, protecting the compressor motor from overload, e.g. after defrost
The valve limits subcooling
The valve prevents motor overheating by injecting liquid into the compressor

29

Stredne ťažká

The lower the liquid temperature upstream of the expansion valve, (at the same mass flow)…


…the lower qo, with Qo unchanged
…the higher the specific refrigerating effect qo [kJ/kg] and the higher the cooling capacity Qo
…the lower qo and the lower Qo
…the lower qo and the lower energy efficiency

30

Stredne ťažká

How should the MOP point of an expansion valve be selected relative to the highest normal evaporating temperature?


About 7 K lower than that temperature
Higher by approx. 20 K
A few kelvin higher (approximately 7 K)
Freely – the MOP value is irrelevant

31

Stredne ťažká

What is the function of the suction pressure regulator?


It prevents a drop in suction pressure and, if necessary, shuts down the refrigeration system.
To maintain the suction pressure at the highest possible level.
It limits the suction pressure and protects the compressor from excessively high suction pressure.
It maintains the evaporation pressure at a constant level.

32

Stredne ťažká

What is the function of the valve regulating water flow through the condenser?


To maintain the condensing pressure at the lowest possible level.
To maintain the condensing pressure at the highest possible level.
To maintain the water temperature at the highest level.
To maintain the condensing pressure at a constant level.

33

Stredne ťažká

The use of a refrigerant distributor requires a thermostatic expansion valve ...


... with an adsorption-type sensor filling.
... with external pressure equalisation.
... with internal pressure equalisation.
... with a MOP function.

34

Stredne ťažká

What properties should good insulation materials have?


An antistatic coating
High thermal conductivity
Low thermal conductivity (and low water absorption, vapour tightness)
The ability to absorb large amounts of moisture

35

Stredne ťažká

When is refrigerant vapour superheated?


When the compressor motor temperature rises excessively
When the evaporating temperature is lower than the ambient temperature
When its temperature is higher than the saturation temperature corresponding to its pressure
When the pressure on the discharge side is higher than on the suction side

36

Stredne ťažká

How can you check whether the liquid refrigerant is reaching the expansion valve without vapour bubbles?


We check using a liquid pressure gauge.
We are unable to check this.
We check using a pressure gauge fitted on the discharge side of the compressor.
We check this using a sight glass.

37

Stredne ťažká

Where does the liquid line run?


Between the evaporator and the suction-line heat exchanger
Between the evaporator and the compressor
From the condenser (liquid receiver) to the expansion valve
Between the compressor and the condenser

38

Stredne ťažká

What is the function of the liquid receiver in a refrigeration system?


To collect liquid refrigerant and excess oil
To further subcool the condensed refrigerant
To store refrigerant and compensate for changes in the circulating charge as the heat load varies
To act as a reserve when the required charge is unknown

39

Stredne ťažká

What is the purpose of the liquid receiver during service work?


It further subcools the refrigerant before the expansion valve
It is a reserve when the installer does not know the required charge
It allows pump-down and temporary storage of the refrigerant
It collects excess oil circulating in the system

40

Stredne ťažká

Where should the liquid receiver be installed?


It should be installed downstream of the condenser, upstream of the expansion valve.
It should be fitted just before the compressor.
It should be fitted after the evaporator.
It should be fitted between the compressor and the condenser.

41

Stredne ťažká

What is the function of the suction pressure regulator fitted to the suction pipe when the compressor starts up?


It closes when the suction pressure upstream of the compressor drops.
It regulates the evaporation pressure.
It regulates the condensing pressure.
It opens when the suction pressure upstream of the compressor drops.

42

Stredne ťažká

The use of microchannel heat exchangers, compared with conventional heat exchangers made of copper tubes and fins, results in:


A reduction in the system’s energy efficiency.
An increase in the amount of refrigerant in the system and an increase in condensing pressure.
There is no effect whatsoever on either the amount of refrigerant or energy efficiency.
A reduction in refrigerant charge and, typically, higher energy efficiency.

43

Stredne ťažká

Which refrigerants belong to the HFC group?


R134a, R404A, R507A, R410A.
R11, R12, R502.
R22, R401A.
R134a, R32, R22, R507A, R290.

44

Stredne ťažká

Which refrigerants belong to the HFO group?


R1234yf, R1234ze(E).
R22, R12.
R134a, R290.
R134a, R404A.

45

Stredne ťažká

What are the characteristics of R410A refrigerant compared to R407C refrigerant?


The saturation pressure of both refrigerants is roughly the same.
The saturation pressure of R407C is 150% higher than that of R410A.
The saturation pressure of R410A refrigerant is higher than that of R407C.
The saturation pressure of R407C refrigerant is much higher than that of R410A.

46

Stredne ťažká

What does the TEWI indicator define?


Total Equivalent Warming Impact: the sum of direct emissions (leakage and refrigerant losses at disposal) and indirect emissions (CO₂ from generating the energy consumed by the equipment) over its lifetime
The impact of a refrigerant on the ozone layer
The global warming potential of a gas relative to CO₂ over a 100-year horizon
The ability of the ozone layer to recover

47

Stredne ťažká

What are the characteristics of R452A compared with R404A?


The temperature glide of R452A is half that of R404A
It is a flammable and toxic single-component HFC
It is a non-flammable (A1) HFC/HFO blend with properties similar to R404A and a GWP about 45% lower
Both are azeotropic and have no temperature glide

48

Stredne ťažká

What distinguishes R1234yf from R134a?


Higher toxicity
A higher critical temperature
It is mildly flammable (class A2L), whereas R134a is non-flammable (A1)
A higher normal boiling point

49

Stredne ťažká

How does CO₂ (R744) compare with R134a?


It has identical properties and is a drop-in replacement for R134a
It has a lower critical temperature, much higher operating pressures and a much higher volumetric cooling capacity (smaller compressors and pipes)
Unlike R134a, it is an azeotropic mixture
Its temperature glide is 7 K greater than that of R134a

50

Stredne ťažká

Which of the following is NOT a fluorinated greenhouse gas?


Perfluorocarbons (PFCs).
Carbon dioxide (CO₂).
Hydrofluorocarbons (HFCs).
Sulphur hexafluoride (SF6).

51

Stredne ťažká

What is the greenhouse effect?


Greenhouse gases absorb and re-emit the Earth's infrared radiation, warming the lower atmosphere
Dust in the atmosphere reflects sunlight, lowering the average surface temperature
Chlorine compounds destroy stratospheric ozone, increasing UV radiation at the surface
Clouds reflect ultraviolet radiation, which makes the air near the surface warmer

52

Ľahká

What does the GWP indicator mean?


The annual rise in mean air temperature caused by the emission of 1 kg of the gas
Global Warming Potential: the climate warming impact of 1 kg of a gas compared with 1 kg of CO₂ (GWP = 1) over a defined time horizon, usually 100 years
Ozone depletion potential
The ability of a substance to restore the ozone layer

53

Stredne ťažká

How do refrigeration systems contribute to the greenhouse effect?


Indirectly (through energy consumption) and directly (through emissions of refrigerant into the atmosphere)
Only through CO₂ given off by the compressor motor
Only through the heat rejected by the condenser
Through oil emitted into the atmosphere from the condenser and filter

54

Stredne ťažká

What is the greenhouse effect?


The formation of a layer that traps only heat from fuel combustion in aircraft
The trapping of heat in the Earth's atmosphere, which hinders the radiation of heat into space
The filtering of solar radiation by the atmosphere
The absorption of solar radiation by the Earth's surface

55

Stredne ťažká

Which EU regulation is currently the primary piece of legislation governing the use of fluorinated greenhouse gases (F-gases) in the European Union?


Regulation (EU) 2015/1188
Directive 2009/125/EC
Regulation (EU) 2024/573
Regulation (EU) No 517/2014

56

Stredne ťažká

What is the main objective of Regulation (EU) 2024/573?


Standardising metal recycling standards
Prevention of F-gas emissions and the achievement of the EU’s climate targets
To reduce taxes on refrigeration equipment
To facilitate the import of electrical appliances

57

Stredne ťažká

What are the ecodesign obligations of manufacturers of refrigerating appliances?


Only declaring F-gas quantities under Regulation (EU) No 517/2014
Only using energy labels under Regulation (EU) 2024/573
Meeting implementing regulations (e.g. 2019/2019, 2015/1095): efficiency, spare parts, reparability
Only implementing an ISO 9001 quality management system

58

Stredne ťažká

What is the main objective of EU ecodesign legislation (Directive 2009/125/EC, now Regulation (EU) 2024/1781 – ESPR)?


To standardise the appearance of products in the EU
To reduce the negative environmental impact of products by improving energy efficiency, durability and recyclability
To increase sales of electrical appliances in the EU
To facilitate imports from outside the EU

59

Stredne ťažká

What is the function of a ball valve in a refrigeration system?


It measures the moisture content of the refrigerant
It prevents excessive pressure build-up in the system
It regulates the temperature of the refrigerant
Enables the refrigerant flow to be completely shut off

60

Ľahká

What is the main function of a safety valve?


Discharges refrigerant when the set pressure is exceeded
Prevents the evaporator from freezing
It controls the oil level in the compressor
It monitors the moisture content of the refrigerant

61

Stredne ťažká

How do certain gases contribute to the greenhouse effect?


They limit UV radiation reaching the Earth's surface, changing the heat balance
They deplete the ozone layer, so more solar radiation reaches the surface
They trap thermal radiation that the Earth would otherwise emit into space
They heat the air through chemical reactions with atmospheric oxygen and nitrogen

62

Stredne ťažká

What is the purpose of a sight glass (with moisture indicator)?


Measuring condenser temperature
Regulating compressor pressure
Visual assessment of the refrigerant condition in the liquid line (bubbles) and of system moisture
Emergency shut-off of flow

63

Stredne ťažká

What is the function of the temperature regulator in a refrigeration system?


Controls the operation of the compressor and valves to maintain the set temperature
To maintain a constant pressure in the compressor
It restricts oil flow
It drains excess refrigerant into the receiver

64

Ťažká

What is the role of a suction liquid separator (also in systems with flammable or toxic refrigerants)?


It prevents liquid refrigerant from entering the compressor
It heats the refrigerant before the evaporator
It is used only to measure moisture
It separates liquid from oil

65

Ťažká

What is the function of an oil separator in systems using flammable or toxic refrigerants?


It prevents liquid from entering the compressor
They are used solely to measure the moisture content of the refrigerant
Heats the refrigerant before it enters the evaporator
Separates oil from the refrigerant and facilitates the return of oil to the compressor

66

Stredne ťažká

What is the purpose of oil level regulators in a refrigeration system?


They drain off excess refrigerant
They control the pressure in the condenser
They control the evaporator temperature
Maintains the correct oil level in the compressor

67

Stredne ťažká

What is the function of the liquid receiver in relation to system tightness?


It regulates the oil returning to the compressor
It keeps the whole system at constant pressure regardless of load
It controls the evaporating temperature by varying the circulating charge
It stores refrigerant; checking its liquid level helps detect charge loss

68

Stredne ťažká

What is the role of a gauge manifold with thermometers (temperature probes)?


It measures pressures and temperatures to determine superheat and subcooling and thus assess the system charge (indirect leak check)
It monitors refrigerant moisture content
It controls oil level
It relieves pressure if it is exceeded

69

Stredne ťažká

What is the role of defrost controls?


They control compressor discharge pressure during defrost
They drain excess oil from the evaporator to the receiver
They protect the evaporator from icing and damage that could lead to leaks
They monitor the moisture content of the refrigerant

70

Ľahká

What is the unit of pressure in the International System of Units (SI)?


Pa (pascal)
atm (standard atmosphere)
bar (gauge)
psi (pound per square inch)

71

Stredne ťažká

Where can the lists of fluorinated greenhouse gases be found?


In the national Act on ozone-depleting substances and certain fluorinated greenhouse gases
In the Vienna Convention for the Protection of the Ozone Layer
In Annexes I–III to Regulation (EU) 2024/573 of the European Parliament and of the Council
In a regulation of the Minister of Economy on the list of fluorinated greenhouse gases

72

Stredne ťažká

Where can the lists of ozone-depleting substances be found?


In Annexes I and II to Regulation (EU) 2024/590 of the European Parliament and of the Council
In the Vienna Convention for the Protection of the Ozone Layer
In a regulation of the Minister of the Environment on the list of controlled substances
In the national Act on ozone-depleting substances and certain fluorinated greenhouse gases

73

Ťažká

Why are PFAS formed by the decomposition of certain F-gases (e.g. TFA from HFOs) problematic?


They are very persistent, accumulate in the environment (e.g. water) and may be toxic
They cause rapid cooling of the atmosphere
They are readily biodegradable
They are climate- and environment-neutral

74

Stredne ťažká

Where and by when must entities obliged under the Polish Act of 15 May 2015 submit annual reports on ODS and F-gases?


By 28 February of the following year, electronically via the Reports Database (BDS) run at the Institute of Industrial Chemistry (ICHP)
By the end of the calendar year, on a form at a regional office of the Office of Technical Inspection (UDT)
By 31 January, in the Central Register of Operators (CRO)
By 31 March, electronically to the Ministry of Climate and Environment

75

Stredne ťažká

Which installation measure has a major impact on compressor energy efficiency?


Installing a suction line smaller than recommended
Proper evacuation and dehydration of the system (removing air and moisture)
Omitting the filter-drier to reduce flow resistance
Charging extra refrigerant 'as a reserve' above the nameplate value

76

Stredne ťažká

How does regular oil-level monitoring affect compressor operation?


It ensures proper lubrication and limits wear and energy losses
It allows any type of oil to be topped up
It allows the crankcase heater to be omitted
It increases cooling capacity above nominal

77

Ľahká

How do system leaks affect compressor energy efficiency?


They affect only safety, not energy use
They improve efficiency because condensing pressure drops
Refrigerant loss reduces capacity and increases energy use (longer run times, higher superheat)
No effect as long as the system still cools

78

Stredne ťažká

Regulation (EU) 2024/590 relates to:


Conditions for F-gas certification of companies recovering and reclaiming refrigerants
Ozone-depleting substances
Alternative refrigerants replacing fluorinated greenhouse gases
Health and safety during refrigerant recovery

79

Stredne ťažká

What is the significance of proper suction and discharge pressure control?


The highest possible condensing pressure is best
Pressures do not affect energy use
The lowest possible suction pressure is best
It keeps the compressor at optimal conditions (suction pressure as high and condensing pressure as low as permissible)

80

Stredne ťažká

Which maintenance measure reduces compressor energy consumption?


Replacing the filter-drier when the pressure drop or moisture indicator shows it is necessary
Permanently disabling the crankcase heater
Topping up refrigerant at every service visit
Raising the high-pressure switch setting

81

Stredne ťažká

How does air (non-condensable gas) in the system affect operation?


It improves condenser heat transfer
It only affects the sight-glass indication
It lowers the condensing pressure
It raises the condensing pressure and reduces efficiency

82

Stredne ťažká

What role do controls play in compressor efficiency?


They enable optimised operation and lower energy use (e.g. floating head pressure, capacity matching)
They provide safety only, with no energy effect
They increase the circulating refrigerant charge
They matter only in NH₃ systems

83

Stredne ťažká

How does suction superheat at the compressor affect efficiency?


Superheat has no effect
Zero suction superheat is optimal
Excessive superheat reduces efficiency and raises the discharge temperature
The higher the superheat, the higher the efficiency

84

Stredne ťažká

How does correct system layout affect efficiency?


It doesn't matter
It affects only appearance
It shortens pipe runs and limits pressure drops and energy losses
Longer pipes improve subcooling and always increase efficiency

85

Stredne ťažká

How important is suction pipe insulation?


It increases energy consumption
It has no effect
It is needed only for appearance
It limits heat gain and excessive superheat, improving efficiency

86

Stredne ťažká

Which measure most improves condenser energy efficiency?


Regular cleaning of heat-exchange surfaces
Increasing the refrigerant charge
Reducing fan speed to the minimum
Raising the condensing pressure set point

87

Ľahká

How does a dirty condenser affect the operation of the refrigeration system?


It has no effect
It improves efficiency
Causes an increase in pressure and energy consumption by the compressor
It lowers the condensing pressure

88

Ľahká

Why is adequate airflow through an air-cooled condenser important?


It ensures effective heat rejection and low condensing pressure
It affects only noise
The lower the airflow, the lower the condensing pressure
It doesn't matter

89

Stredne ťažká

Which refrigerants damage the ozone layer?


All refrigerants containing fluorine and hydrogen in their molecules
All refrigerants containing chlorine or bromine in their molecules
All natural refrigerants
All refrigerants containing carbon in their molecules

90

Ľahká

How does the presence of limescale in a water-cooled condenser affect performance?


It has no effect
It improves heat transfer
Impairs heat exchange and increases energy consumption
It lowers the condensation temperature

91

Stredne ťažká

How does correct condensing pressure control affect efficiency?


It has no effect
It keeps the lowest pressure that still ensures proper expansion-valve feed, reducing energy use
It always increases energy use
It is best to keep a constant high condensing pressure all year

92

Ľahká

How do condenser leaks affect energy efficiency?


They lower the temperature
Have no effect
Causes refrigerant loss and a drop in efficiency
They improve efficiency

93

Ľahká

How important is the correct positioning of an air-cooled condenser?


It doesn’t matter
It should be installed in a well-ventilated area with unobstructed airflow
It should be close to heat sources
It should be housed in a small room

94

Ľahká

How does hot air recirculation affect the condenser?


It reduces the pressure
It has no effect
It improves efficiency
Impairs cooling and increases energy consumption

95

Stredne ťažká

How does insulation of heating and DHW pipework affect the efficiency of a heat pump system?


It doesn't matter
It increases pressure
It impairs cooling
It reduces energy losses and improves overall system efficiency

96

Stredne ťažká

Which measure most improves the energy efficiency of an air-cooling evaporator?


Defrosting at the right time and keeping the fins clean
Increasing the refrigerant charge above nominal
Raising the condensing temperature by a few kelvin
Restricting the airflow through the evaporator

97

Ľahká

How does evaporator icing affect the system’s operation?


It has no effect
It improves cooling performance
It lowers the condensation temperature
Impairs heat exchange and increases energy consumption

98

Ľahká

How does dirt on the evaporator surface affect its performance?


It reduces the pressure
Impairs heat exchange and increases energy consumption
It improves efficiency
It has no effect

99

Ľahká

What maintenance task is crucial for the evaporator?


Lack of maintenance
Increasing the refrigerant charge
Regular cleaning and defrosting
Reduced airflow

100

Stredne ťažká

What does a Certificate A2 for natural persons (Implementing Regulation (EU) 2024/2215) authorise?


Only recovery of F-gases from equipment containing less than 3 kg (or 6 kg in hermetically sealed systems)
All activities (leak checks, installation, repair, maintenance, servicing, decommissioning, recovery) involving F-gases and hydrocarbons in equipment containing less than 3 kg, or less than 6 kg in labelled hermetically sealed systems
All activities involving equipment using CO₂ (R744)
Only leak checks that do not entail breaking into the refrigerant circuit

101

Ľahká

How does superheat at the evaporator outlet affect efficiency?


It always improves performance
It has no effect
It only causes a temperature drop
Excessive superheat reduces energy efficiency

102

Ľahká

How do leaks in the evaporator affect efficiency?


Have no effect
These cause refrigerant loss and a drop in efficiency
Improves performance
Increase capacity

103

Ľahká

How important is correct expansion valve adjustment?


Causes leaks
Ensures optimal evaporator charge and improves efficiency
It doesn’t matter
It increases energy consumption

104

Ľahká

How does inadequate insulation of suction (or secondary-coolant) pipes affect evaporator performance?


It causes cooling losses and increased energy use
It lowers the condensing temperature
It has no effect
It improves efficiency

105

Ľahká

How does correct TEV adjustment affect system energy efficiency?


It ensures optimal superheat and improves efficiency
It has no effect
It causes leaks
It increases energy use

106

Ľahká

What happens if the superheat set by the TEV is too high?


The refrigerant charge will increase
Cooling efficiency will improve
Efficiency will drop because the evaporator is not being fully utilised
It has no effect

107

Stredne ťažká

How does too low superheat setting on the TEV affect performance?


It increases operational safety
It reduces refrigerant flow
It may lead to improved efficiency, but it increases the risk of the compressor becoming flooded with liquid
It has no effect

108

Ľahká

How do contaminants in the system affect the operation of the TEV?


They lower the temperature
They can cause it to become blocked and reduce efficiency
Have no effect
They improve its performance

109

Ľahká

What role does the filter-drier play in terms of system efficiency?


It lowers the temperature
Removes moisture and contaminants, improving the system’s efficiency
It doesn’t matter
It increases the amount of refrigerant

110

Ľahká

How does proper insulation of components (e.g. pipes near the TEV) affect the system?


It increases energy consumption
Prevents unwanted heat gains and improves efficiency
It causes leaks
It doesn’t matter

111

Stredne ťažká

What is the scope of Regulation (EU) 2024/573?


Only requirements for periodic leak checks of refrigeration equipment
Health and safety requirements for brazing and welding on refrigeration installations
Design requirements and conformity assessment for pressure equipment
Limiting emissions, use and marketing of F-gases, HFC phase-down, certification and reporting

112

Ľahká

How important is it to check the operation of the condensing pressure control valve in the system?


It has no effect
It causes a significant rise in temperature
It increases energy consumption
Ensures operation within the optimum pressure range and reduces energy losses

113

Ľahká

How does the correct selection of a TEV affect energy efficiency?


It lowers the temperature
It increases the amount of refrigerant
Ensures the system is matched to its capacity and operates optimally
It doesn’t matter

114

Stredne ťažká

How can you tell that the system has been overcharged with refrigerant?


Under normal operating conditions the condensing pressure and subcooling rise markedly because excess liquid floods the condenser and reduces its active surface
The compressor runs at a lower load and the suction pressure drops
Even under a very small heat load, frost forms on the suction line
It cannot be checked, because the sight glass is not intended for this

115

Stredne ťažká

Before charging the unit with refrigerant, it is essential to…


…check the compressor suction and discharge connections
…carry out a tightness test (and evacuate the system)
…carry out a trial start-up
…fill in the unit's data sheet

116

Stredne ťažká

What information must appear on the label of equipment containing F-gases?


The weight and capacity of the pipework and the colour code of the casing paint
That it contains an F-gas, its designation, quantity in kg and t CO₂ eq, and GWP
Only the trade name of the refrigerant and the unit's serial number
The manufacturer's logo, the unit weight and year of manufacture from the rating plate

117

Ľahká

What is the base unit of temperature according to the International System of Units (Système International d’Unités)?


°C
°F
K
°R

118

Stredne ťažká

Which set of information best reflects the content of the equipment records required by Regulation (EU) 2024/573?


Only the date of installation and the installer's name
The owner, installer and service technician of the unit
Operator details, equipment details, type and quantity of refrigerant, and information on servicing and repairs
The make and model of the unit

119

Ťažká

Which statement about installing Schrader valves is correct?


Hydrocarbons leak through Schrader valves
Schrader valves must not be used in R744 systems
When brazing the valve body, the core must be removed, then refitted and tightened to the correct torque
All Schrader cores are suitable for all refrigerants

120

Ťažká

How does an undercharge affect the high-pressure side (without discharge pressure control)?


Discharge pressure higher, subcooling lower
Discharge pressure higher, subcooling higher
Discharge (condensing) pressure and subcooling will both be lower
Discharge pressure lower, subcooling higher

121

Ťažká

What is the benefit of adding helium as a tracer gas to nitrogen in a pressure test?


It has a distinctive odour that helps locate the leak
It has a higher pressure than pure nitrogen in the same cylinder
Its small atoms pass easily through leaks and are detected
It reacts with refrigerant residues, producing a visible colour change

122

Stredne ťažká

Who is responsible for keeping the equipment records?


The operator of the unit or system.
There is no such obligation.
The person responsible for risk assessment.
The equipment maintenance technician.

123

Ťažká

What can be the effect of a relief valve lifting repeatedly?


The valve no longer opens
The valve may not reseat tightly and its set (opening) pressure may decrease
The set pressure increases
The valve stays fully open permanently

124

Stredne ťažká

Where are oil traps installed on the suction line?


Immediately before the compressor suction connection
Before the safety valve on the suction side
At the inlet to every component of the refrigeration system
At the bottom of vertical suction risers with upward flow

125

Ťažká

What is the relationship between the pressure (p) and temperature (T) of nitrogen at the start (1) and end (2) of a tightness test (p absolute, T in kelvin)?


p₂ = (p₁ × T₁)/T₂
p₂ = T₂/(p₁ × T₁)
p₂ = (p₁ × T₂)/T₁
p₂ = T₁/(p₁ × T₂)

126

Stredne ťažká

Which symptoms with the compressor running indicate a refrigerant leak (undercharge)?


Low suction pressure, high superheat and negligible subcooling
Sight glass full of liquid and rising oil level in the crankcase
Rising condensing and suction pressures with no superheat
Rising liquid level in the receiver and increasing subcooling

127

Stredne ťažká

Which components of a refrigeration system are potential leak points subject to leak checks?


Only suction-side components
Only high-pressure-side components
Joints, valves (including stems), seals (including those on replaceable filters and driers), parts subject to vibration and connections to safety and measuring devices
Hermetic compressors, liquid receivers and liquid separators

128

Stredne ťažká

What pressure is used for the pressure tightness test of an installation?


The pressure specified in EN 378-2 or by the manufacturer, not exceeding the maximum allowable pressure of the system (PS)
A pressure equal to the maximum pressure measured during operation
A pressure chosen by the technician based on experience
Always 30 bar

129

Stredne ťažká

At which points of the unit must the leak check be carried out?


At all points where there is a potential risk of refrigerant leakage
Only at connections of measuring instruments
Only on discharge-side components
Only on compressor shut-off valves, solenoid valves and filters

130

Stredne ťažká

When can a unit be considered tight after a pressure test?


When the pressure remains constant during the test (allowing for temperature-related changes); any unexplained pressure drop requires the leak to be located
When the pressure drop does not exceed 0.1 bar regardless of the test duration
When gas bubbles appear after immersion in water
When it has been checked with a fixed electronic detector

131

Stredne ťažká

Which legal act currently sets out the obligation to check stationary refrigeration equipment containing F-gases for leaks, and how often this must be done?


Regulation (EU) 2024/573
Commission Regulation (EC) No 1516/2007
Implementing Regulation (EU) 2024/2215
Regulation (EU) No 517/2014

132

Ťažká

Which parts of a refrigeration system should be given particular attention during a leak check?


Joints, valves incl. stems, seals, parts subject to vibration, connections to safety devices
Only condenser connections, because the refrigerant is liquid there
Compressor and receiver connections, because the pressure is highest there
Only compressor connections, because they are the only parts subject to vibration

133

Ľahká

What is the superheat of refrigerant vapour?


The difference between the condensing temperature and the ambient temperature
The amount of heat required to evaporate a liquid
The difference between the actual vapour temperature and the saturation temperature corresponding to its pressure (expressed in K)
The difference between the saturation temperature and the actual liquid temperature in the liquid line

134

Ťažká

Leak checks can be carried out using various methods. Which pair is correct?


Physical and chemical methods
Material quality control methods and electronic methods
Direct and indirect methods
Methods with and without quality control of supplies

135

Ťažká

To whom can leak checks of stationary refrigeration equipment containing F-gases be entrusted?


A natural person holding a certificate covering leak checks (A1, A2 within its charge limit, or E)
A person who has carried out such checks before
Any leak-testing specialist
An employee appointed by the owner of the installation

136

Ťažká

What conditions must be met to use UV dye for leak checking?


It is sufficient that introducing dye into the circuit is technically feasible
Manufacturer approval of the method and a certificate covering breaking into the circuit
A UDT authorisation for pressure testing is required
It is sufficient to have a UV lamp, dye and safety goggles

137

Ťažká

Which leak-checking methods are considered direct methods?


Pressure-change measurement and immersion in water
Vacuum test and foam solution
Nitrogen with tracer gas and pressure measurement
1. gas detection devices (portable or fixed leak detection system), 2. UV detection fluid or dye, 3. bubble/foam solutions

138

Ťažká

What do indirect leak-checking methods involve?


Ultrasonic measurement
A visual and manual check and analysis of parameters: pressure, temperature, compressor current, liquid levels and recharge volume
Leak detection with an electronic detector
Leak detection with UV dye

139

Stredne ťažká

How should the pressure be increased during a pressure tightness test?


Gradually, in stages, checking for leaks at each level until the test pressure is reached
In one step, by fully opening the nitrogen cylinder valve
In any way
As quickly as possible

140

Stredne ťažká

What electronic equipment should be used for leak checking?


Only hot-cathode devices
Only detectors with an infrared sensor
Only devices with an 'ion pump' sensor
Detectors suited to the refrigerant in the system, with appropriate sensitivity, checked periodically

141

Stredne ťažká

What documentation should be checked before starting a leak check?


Attendance sheets of the plant-room staff for the year
The equipment records – especially recurring problems and previous leaks
The operator's fixed-asset inventory ledger
Only the installation invoice and the first start-up report

142

Stredne ťažká

What information must be recorded in the leak check report?


The method used, the time spent on site and the cost of repair
Date, number and location of leaks, how they were repaired, technician details and signature
Only the number of leaks found and the date of the check
The date, a general note about the leak and the operator's signature

143

Stredne ťažká

What pressure should be used for the pressure tightness test?


A pressure not exceeding the maximum allowable pressure of the system (PS)
Any pressure, at the technician's discretion
Always 2–3 bar
Always 10–12 bar

144

Stredne ťažká

What is the temperature glide of a refrigerant?


A property of single-component refrigerants, for which one saturation temperature corresponds to a given pressure
The temperature drop of the refrigerant across the expansion valve
The temperature rise of the vapour in the compressor
In zeotropic mixtures, the difference between the temperatures at the start and end of a phase change (boiling or condensation) at constant pressure

145

Ťažká

What does a vacuum (decay) test involve?


After isolating the pump, you check whether the system pressure rises
With the pump running, you watch the vacuum gauge reading
The pump runs continuously to hold the required vacuum for the test
The pump is restarted every time the system pressure rises

146

Ťažká

How often should leak tests be carried out on equipment containing 1.5 kg of R404A refrigerant (5.9 tonnes of CO₂ equivalent)?


Once every six months.
On initial commissioning.
Only when servicing the unit.
At least once every 12 months.

147

Ťažká

How often should leak tests be carried out on equipment containing 7 kg of R404A refrigerant (27.45 tonnes of CO₂ equivalent)?


Once every six months.
On initial commissioning.
Only when servicing the unit.
At least once every 12 months.

148

Stredne ťažká

In which equipment is a leakage detection system required?


Equipment with 50 t CO₂ eq or more of F-gases, regardless of equipment type
Equipment with ≥ 500 t CO₂ eq of Annex I F-gases (or ≥ 100 kg of Annex II Section 1 gases)
Equipment with 5 t CO₂ eq or more of F-gases, regardless of equipment type
Equipment with 30 kg or more of F-gases, regardless of their GWP

149

Ťažká

Under Regulation (EU) 2024/573, a leakage detection system is mandatory when:


the F-gas charge of the refrigeration equipment is 500 t CO₂ eq or more
the equipment operates in an enclosed space
the equipment contains a flammable refrigerant in any quantity
the charge is 100 kg or more of ozone-depleting substances

150

Ťažká

Which leak-checking method may NOT be used by a holder of a Category E certificate?


Visual inspection
Leak checking with a fluorescent dye introduced into the circuit
Measurement with a handheld electronic detector
Checking with a foaming solution

151

Stredne ťažká

What should you check before using a portable electronic leak detector?


That it suits the refrigerant and has been checked as the manufacturer requires
That it has been zeroed close to the suspected leak point
That it has an infrared sensor, as only this type is permitted
That it holds a valid UDT inspection certificate

152

Stredne ťažká

Which certificate types (A1, A2, B, C, D, E) authorise leak checks of equipment containing F-gases?


All except D
A1, A2 and E
Only E
Only A1 and A2

153

Ťažká

Within what timeframe must a leak test be carried out on a stationary refrigeration system after a leak has been repaired, in accordance with EU Regulation 2024/573 on F-gases?


At any time.
Immediately after the repair.
At the next periodic inspection.
Between 24 hours and 1 month after the repair.

154

Ťažká

How often must refrigeration equipment containing ≥500 t CO₂ eq of F-gases be checked if (contrary to Article 6) no leakage detection system is installed?


Every 6 months
Every 12 months
Every 3 months
Every month

155

Stredne ťažká

Why is it advisable to subcool the liquid refrigerant?


To allow a smaller expansion valve to be used
To lower the evaporating temperature in the evaporator
To allow a condenser with a smaller heat-exchange surface to be used
To ensure that liquid free of vapour bubbles enters the expansion valve

156

Stredne ťažká

What must be done after repairing a leak in the refrigeration unit of a refrigerated trailer?


Update the equipment records and carry out a leak check (it may be done directly after repair)
Charge an alternative refrigerant, start up and measure the parameters
Visually inspect only the bolted and brazed joints near the repair
Issue the invoice and leave the leak check to the next periodic service

157

Stredne ťažká

Recovery of fluorinated greenhouse gases means:


The final decommissioning and withdrawal from service or use of a product or piece of equipment containing fluorinated greenhouse gases.
The collection and storage of fluorinated greenhouse gases from containers, products and equipment during maintenance or servicing or prior to their disposal.
The reuse of fluorinated greenhouse gases following a basic purification process.
The reprocessing of fluorinated greenhouse gases to achieve their specified standard properties.

158

Stredne ťažká

Who is authorised to recover refrigerant from stationary refrigeration equipment containing F-gases?


The administrator of the operator's account in the register
The operator
A natural person holding a certificate of the relevant type (A1; A2. or D within their charge limit)
The owner of the installation

159

Stredne ťažká

How must recovered refrigerants be stored?


In any used refrigerant cylinder, provided it is leak-tight
In a disposable (non-refillable) cylinder that held the same refrigerant
In any pressure vessel that has some form of approval
In a labelled recovery cylinder with a dual valve and a valid inspection

160

Stredne ťažká

When should the recovery of fluorinated greenhouse gases be carried out:


Before the final disposal of equipment and, where applicable, during its servicing and maintenance.
Always during servicing and maintenance of equipment.
Only prior to the final disposal of equipment.
Before each leak test of the equipment.

161

Stredne ťažká

What should be done if recovered refrigerant is contaminated (e.g. with acid, air or moisture)?


Add a special contaminant neutraliser
Clean the mixture yourself using a filter-drier
Hand it over to a specialised, authorised company for reclamation or destruction
Pass it through a particle filter and reuse it

162

Stredne ťažká

What should be done if different refrigerants have been mixed in a storage cylinder?


Separate the mixture into its components yourself
Add a special refrigerant to the mixture
Hand the mixture over to an authorised company – as a rule for destruction
Pass it through a filter-drier and reuse it

163

Stredne ťažká

How does push-pull refrigerant recovery work?


Refrigerant is drawn alternately from the suction and discharge sides of the compressor
The recovery unit draws vapour from the recovery cylinder and pushes it into the system; the pressure difference forces liquid refrigerant out of the system into the cylinder
Nitrogen is injected into the system, pushing the refrigerant into the atmosphere
The recovery unit draws vapour from the system and condenses it in the cylinder

164

Stredne ťažká

What are the options for managing waste refrigerant?


Recycling, reclamation, destruction
Reclamation, recovery
Recovery, disposal
Disposal, storage

165

Stredne ťažká

Which management option restores recovered refrigerant to a quality equivalent to virgin product, so that it can be used by any undertaking?


Destruction
Storage
Recycling
Reclamation

166

Stredne ťažká

The lower the evaporating temperature, …


…the greater the density of the suction vapour and the greater the refrigerant mass flow rate
…the lower the density of the suction vapour and the greater the cooling capacity of the compressor
…the lower the density of the suction vapour and the lower the refrigerant mass flow rate
…the greater the density of the suction vapour and the lower the refrigerant mass flow rate

167

Stredne ťažká

How must transportable pressure vessels (e.g. refrigerant cylinders) be marked?


Only with weight and capacity marks
Among other things: the number of the design and testing standard, marks of the approving country and the inspection body, the date of the initial inspection, and the manufacturer's and operational marks
The marking is optional
With the manufacturer's logo and date of manufacture

168

Stredne ťažká

The recovery of refrigerants does not require the use of:


An electronic leak detector.
A refrigerant recovery station.
Scales with a measurement range suitable for the size of the cylinder being filled.
Hoses with shut-off valves.

169

Stredne ťažká

What functions does the compressor perform in a refrigeration system?


The compressor condenses the refrigerant.
The compressor creates a vacuum on the suction side of the system
The compressor compresses ambient air and increases the pressure of the refrigerant.
The compressor draws in refrigerant vapour from the evaporator, compresses it, and then forces it into the condenser, raising the pressure to the required condensing pressure.

170

Ľahká

What is the compression ratio of a compressor?


The ratio of discharge pressure to the effective capacity of the compressor (p/Vk)
The amount of refrigerant compressed per cycle relative to heat capacity
The ratio of suction pressure to discharge pressure (po/pc)
The ratio of absolute discharge pressure to absolute suction pressure (pc/po)

171

Stredne ťažká

What is compressor flooding (liquid slugging)?


Flooding of the compressor by rainwater
A large amount of liquid refrigerant in a flooded evaporator, which is a normal operating condition
Excess oil in the condenser
Liquid refrigerant or oil entering the compression chamber

172

Stredne ťažká

Within what range is the compressor motor speed typically controlled using a frequency inverter?


Approximately 30 to 75 Hz, corresponding to about 60–150% of nominal capacity (depending on the compressor manufacturer)
From approximately 10% to 90% of nominal capacity
By a maximum of 10%
Speed control does not change the cooling capacity

173

Ľahká

What is the theoretical displacement (swept volume flow) of a compressor?


The volume of a single cylinder in cm³
The volume of refrigerant flowing in one piston cycle under actual operating conditions
A value expressed by the coefficient of performance (COP)
The volume of vapour drawn in per unit of time, determined by the compressor's geometry and speed (stated by the manufacturer, e.g. in m³/h)

174

Stredne ťažká

Why is it essential to observe the correct phase sequence for scroll compressors and screw compressors?


Because this type of compressor has difficulty starting up if the phase sequence is changed.
Because the motor speed would decrease, and consequently the compressor’s capacity.
Because these types of compressors are sensitive to voltage drops.
Because changing the phase sequence would reverse the direction of rotation of the compressor rotors, which could result in damage to the compressors.

175

Stredne ťažká

What compression ratio should each stage of a two-stage vapour-compression system have (rule of thumb)?


Greater than 18
Less than approximately 8
Greater than 10
Equal to 1

176

Stredne ťažká

Why is a shaft seal necessary in open-type compressors?


To protect the crankshaft bearing
To ensure the bearing remains lubricated
To prevent air from entering and refrigerant from leaking out of the compressor
Only to prevent oil leakage

177

Stredne ťažká

How can you check whether the liquid refrigerant is sufficiently subcooled?


Check whether the liquid distributor upstream of the evaporator feels warm
Compare the liquid-line temperature with the saturation temperature at the measured condensing pressure
Check by touch whether the condenser outlet is noticeably colder than ambient
Check whether the whole evaporator surface is covered with an even layer of frost

178

Stredne ťažká

Why is the compressor crankcase heated?


To limit refrigerant migration into, and dissolution in, the oil during standstill
To increase dissolution of refrigerant in the oil and improve its viscosity
To dehydrate the oil
To keep the lubricating oil liquid

179

Ľahká

What is the clearance (dead) volume of a reciprocating compressor?


The space between the underside of the piston and the crankcase cover
The volume between the valve plate and the piston crown at top dead centre
The space between the side of the piston and the cylinder
The volume between the valve plate and the piston at bottom dead centre

180

Stredne ťažká

What are compressor packs (racks)?


Several compressors connected in parallel on a common frame with common suction and discharge headers
Units with two-stage compressors
Sets of compressors connected in any configuration
Several air-cooled condensers

181

Stredne ťažká

What is the main advantage of multi-compressor packs?


A smaller refrigerant charge than a single-compressor system
No need for compressor controls and safety devices
Stepwise capacity matching to demand, plus redundancy
Low purchase cost and easy installation without special controls

182

Stredne ťažká

What is meant by the operating envelope (application range) of a compressor?


A range determined only by the evaporating temperature
The permissible range of evaporating and condensing temperatures (to, tk), or the corresponding pressures, within which the compressor may operate
A range determined by the evaporating temperature at a given ambient temperature
The capacity, refrigerant type and dimensions of the compressor

183

Stredne ťažká

What are the basic functions of oil in a compressor?


Absorbing moisture from the refrigerant
Increasing the cooling capacity of the refrigerant
Sealing leaks that develop in the installation
Lubricating bearings and sliding surfaces, removing heat, and sealing clearances (e.g. between piston and cylinder, or rotors)

184

Stredne ťažká

What are the most effective ways of controlling compressor cooling capacity?


Pressure control valves
Partially covering the evaporator
An expansion valve
Changing the displacement: varying the rotational speed or unloading cylinders

185

Stredne ťažká

What does hot-gas bypass capacity control involve?


High-pressure liquid is injected into the suction to increase capacity
Bypass is not used for capacity control
The compressor speed is varied
Part of the hot discharge gas is passed through a bypass valve to the suction side (or evaporator inlet), reducing the effective capacity

186

Stredne ťažká

What is the fundamental difference between hermetic and semi-hermetic compressors?


Semi-hermetic compressors run more quietly as a complete unit
Both can be dismantled; they differ only in cooling capacity
The semi-hermetic compressor has no motor inside the casing
The semi-hermetic casing is bolted (can be opened); the hermetic one is welded

187

Stredne ťažká

How does a scroll compressor work?


A scroll compressor is also known as a turbo compressor.
It is a positive-displacement compressor in which compression results from the interaction of a fixed and an orbiting scroll.
It uses two screws to compress the refrigerant.
It is a type of piston-type device.

188

Stredne ťažká

What physical process takes place in the evaporator?


The secondary fluid (glycol, water) evaporates while the refrigerant condenses
The refrigerant condenses
The refrigerant is subcooled as a liquid
The liquid refrigerant evaporates, absorbing heat, and the vapour is slightly superheated at the outlet

189

Stredne ťažká

What is the purpose of compressor capacity control?


To ensure compressor lubrication
To increase the condensing pressure
To match capacity to the condensing temperature
To match the cooling capacity to the current demand

190

Stredne ťažká

Why is inverter speed control advantageous for refrigeration compressors?


It can be used with any compressor to ensure lubrication
Reducing the speed improves oil return to the compressor
It increases compressor capacity above nominal at any frequency
It enables continuous, smooth control of cooling capacity

191

Stredne ťažká

Does the suction gas temperature affect the cooling capacity of the compressor?


Yes – higher temperature lowers vapour density, mass flow and capacity
Yes, but only if the suction gas is deeply cooled
Yes, but only in reciprocating compressors, not scroll
No – capacity depends only on the compressor displacement

192

Stredne ťažká

In the case of compressor units fitted with an oil level control system, is it necessary to install the compressors at the same height?


Yes.
Only scroll compressors.
No.
Only screw compressors.

193

Stredne ťažká

What functions does a compressor powered by the vehicle’s engine perform in a transport refrigeration system?


This compressor condenses the refrigerant whilst the vehicle is in motion.
The compressor compresses ambient air and increases the pressure of the refrigerant.
This compressor draws in refrigerant vapour from the evaporator, compresses it and then forces it into the condenser whilst the vehicle’s engine is running.
This compressor creates a vacuum on the suction side of the system whilst the vehicle’s engine is switched off.

194

Stredne ťažká

Which media most commonly absorb heat from the refrigerant in the condenser?


Ammonia
Air and CO₂
Air or water
Only a water–glycol mixture

195

Stredne ťažká

What is the function of the condenser in refrigeration systems?


Releasing to the environment the heat absorbed in the evaporator and the heat added during compression
Absorption of heat rejected in the regenerative heat exchanger
Releasing only the heat absorbed in the evaporator into the surroundings
Releasing only the heat from the compressor into the surroundings

196

Stredne ťažká

If the refrigerant temperature on the high-pressure side is above its critical temperature, condensation…


…always occurs regardless of temperature
…does not depend on temperature
…occurs provided a special condenser is used
…does not occur

197

Stredne ťažká

How is liquid subcooling usually achieved in a refrigeration system?


By dissolving the refrigerant in oil
In the final section of the condenser (or in an additional subcooler)
With hot high-pressure vapour
With an additional heat exchanger using liquid nitrogen

198

Stredne ťažká

What is the purpose of condenser fan speed control?


To reduce energy efficiency
Only to protect against exceeding the maximum condensing pressure
To keep the condensing pressure at the correct level
To disperse refrigerant in the event of a leak

199

Stredne ťažká

Which international agreement introduced the global phase-down of HFC production and consumption?


The Vienna Convention for the Protection of the Ozone Layer
The Kyoto Protocol
The Kigali Amendment to the Montreal Protocol
The Paris Agreement

200

Stredne ťažká

Which international treaty governs the phase-out of ozone-depleting substances (CFCs, HCFCs)?


The Montreal Protocol
The Stockholm Convention
The UN Framework Convention on Climate Change (UNFCCC)
The Paris Agreement

201

Ťažká

What is the basis of the GWP values in Regulation (EU) 2024/573?


AR6 for all substances
For HFCs (Annex I) – mainly the IPCC Fourth Assessment Report (AR4); for HFOs and non-fluorinated substances (Annexes II and VI) – the Sixth Assessment Report (AR6)
AR4 for all substances
Each Member State sets its own GWP values

202

Ťažká

An air conditioner (not hermetically sealed) contains 2.5 kg of R410A (GWP 2088). How often must it be checked for leaks?


At least every 12 months (5.22 t CO₂ eq)
No checks required (below 3 kg)
Every 6 months
Every 3 months

203

Ťažká

When is labelled hermetically sealed equipment containing HFCs (Annex I) exempt from leak checks?


Always, regardless of charge
When it contains less than 5 t CO₂ eq
Never – hermetically sealed equipment is always checked
When it contains less than 10 t CO₂ eq, and in residential buildings also when it contains less than 3 kg of F-gases

204

Ťažká

Is a chiller containing 50 kg of R1234ze(E) subject to leak checks under Regulation (EU) 2024/573?


Yes – at least every 6 months (every 12 months with a leakage detection system)
No – HFOs are not subject to leak checks
Yes – every 12 months, because its GWP is low
No – the threshold is 5 t CO₂ eq and 50 kg of R1234ze is below 1 t CO₂ eq

205

Ťažká

In 2026, may an existing refrigeration installation using R404A (GWP 3922) be topped up with virgin refrigerant?


Yes – bans apply only to new equipment
Yes, if the equipment has a leakage detection system
Yes – the ban applies only to equipment ≥40 t CO₂ eq
No – only reclaimed or recycled R404A is allowed (until 1 January 2030)

206

Ťažká

After 1 January 2026, may an R410A (GWP 2088) air conditioner be serviced using virgin R410A?


No – the ban covers all refrigerants with GWP ≥ 750
Only with reclaimed refrigerant
Yes – the servicing ban for air conditioners and heat pumps covers F-gases with GWP ≥ 2500
No – the ban covers all HFCs

207

Stredne ťažká

Can HFC refrigerant recovered during a repair be put straight back into the same equipment without any cleaning (filtering/drying)?


Yes, always
Yes, if the operator agrees
Yes, if less than 24 hours have passed
No – recovered F-gas may be used for filling only after it has been recycled or reclaimed

208

Stredne ťažká

Who may purchase HFCs for servicing refrigeration equipment?


Only a person holding the relevant certificate or an undertaking employing such persons
Any business
Only the equipment operator
Any adult

209

Stredne ťažká

Under what condition may non-hermetically sealed split air conditioning charged with F-gas be sold to an end user?


Only if the unit contains less than 3 kg of refrigerant
When evidence is provided that installation will be carried out by a certified undertaking
When the user signs a statement that they will install it themselves
Unconditionally

210

Stredne ťažká

By when must the holder of an F-gas certificate issued under Regulation (EU) No 517/2014 first complete refresher training or an evaluation process?


By 12 March 2025
Never – the certificate is valid indefinitely
By 12 March 2029 (and then at least every 7 years)
By 31 December 2030

211

Stredne ťažká

What must the holder of a Category I certificate (Regulation 2015/2067) do to continue using it?


Update their knowledge and skills to the level of Certificate A1 (Annex I to Regulation 2024/2215)
Update their knowledge to the level of Certificate E
Nothing – Category I automatically becomes A1
Apply for an extension without training

212

Stredne ťažká

What does Certificate C under Implementing Regulation (EU) 2024/2215 authorise?


Recovery of F-gases from equipment <3 kg
All activities in relation to CO₂
All activities in Article 2(1) in relation to ammonia (NH₃)
Leak checks without breaking into the circuit

213

Stredne ťažká

May a person enrolled in a certification training course carry out certified activities?


Yes – independently, for 6 months
No, never
Yes – under the supervision of a certified person, for no more than 24 months in total
Yes – with no time limit, if employed by a certified company

214

Stredne ťažká

How long must the operator keep the records of equipment subject to leak checks, if they are not kept in a national database?


At least 2 years
At least 1 year
Until the equipment is decommissioned
At least 5 years

215

Ťažká

Since 1 January 2025, may a new single-split air conditioner containing 1.5 kg of R410A be placed on the market?


Yes, if the unit is hermetically sealed
No – single splits <3 kg with F-gases of GWP ≥ 750 are banned
Yes – the ban applies from 2029
Yes – the ban applies only to units >12 kW

216

Ťažká

From when is it prohibited to place on the market split air-to-air systems up to 12 kW containing F-gases with GWP ≥150 (unless required for safety)?


From 1 January 2025
From 1 January 2027
From 1 January 2029
From 1 January 2035

217

Ťažká

Which persistent atmospheric degradation product of R1234yf is classed as a PFAS?


Ozone
Carbon dioxide
Trifluoroacetic acid (TFA)
Carbonic acid

218

Stredne ťažká

What is floating head pressure and what does it achieve?


It increases subcooling by flooding the condenser
It means switching condenser fans off periodically
It lets the condensing pressure fall with ambient temperature, reducing compressor work and raising COP (requires an expansion valve that works at a small pressure difference)
It keeps a constant high condensing pressure all year

219

Stredne ťažká

How do SEER/SCOP differ from EER/COP?


SEER/SCOP apply only to natural-refrigerant equipment
There is no difference – they are synonyms
EER/COP are always higher than SEER/SCOP
SEER/SCOP are seasonal indicators accounting for part load and climate (EN 14825); EER/COP refer to a single operating point (EN 14511)

220

Stredne ťažká

Which design approach can significantly reduce the F-gas charge of a large refrigeration installation?


Larger liquid-line diameters
Omitting pipe insulation
An indirect (secondary-coolant) system or a cascade with a natural refrigerant in the low stage, plus heat exchangers with small internal volume
Adding a second liquid receiver

221

Stredne ťažká

Which information must be entered in the equipment records after a leak check?


Only the equipment's energy consumption
Only the operator's signature
Only the date of the check
The date and result of the check and the identity of the undertaking and person who performed it (with certificate number)

222

Stredne ťažká

What must be done when an indirect method (e.g. parameter analysis) indicates a possible leak?


Carry out a direct-method examination to locate the leak
Top up the refrigerant and end the check
Record it and check at the next periodic inspection
Nothing – indirect methods are sufficient