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)?


t
N
lb (pound)
kg

2

Stredne ťažká

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


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

3

Stredne ťažká

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


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

4

Stredne ťažká

Why does heat flow from the condenser to the surroundings?


Because HFC refrigerants attract heat from 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 the pressure in the condenser is lower than ambient
Because the compressor pushes heat directly into the surroundings

5

Stredne ťažká

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


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

6

Stredne ťažká

What criteria should be considered when selecting a suitable condenser?


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

7

Stredne ťažká

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


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.
Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause a reduction in condensing pressure.
Contaminants do not significantly affect the efficiency and effectiveness of the heat exchange surfaces in condensers.
Contaminants increase the heat transfer area and reduce the condensing pressure.

8

Stredne ťažká

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


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

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 evaporating pressure
A rise in the cooled-air temperature with no effect on capacity
An increase in condenser subcooling

10

Stredne ťažká

What happens when the evaporation temperature drops?


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

11

Stredne ťažká

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


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

12

Stredne ťažká

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


Always, in every air cooler
Only when the system runs continuously
Only when the room air temperature falls below 0 °C
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…


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

14

Stredne ťažká

How does hot gas defrosting of the evaporator work?


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

15

Stredne ťažká

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


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

16

Stredne ťažká

What condition must electric heaters for evaporator defrosting meet?


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

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, hot gas, water spray and natural (at positive temperatures)
Natural only – other methods are ineffective and uneconomic
Electric only – other methods are not permitted in refrigeration

19

Stredne ťažká

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


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

20

Stredne ťažká

MOP in thermostatic expansion valves stands for:


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

21

Stredne ťažká

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


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

22

Stredne ťažká

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


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

23

Stredne ťažká

What does a thermostatic expansion valve control?


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

24

Ľahká

The refrigerant absorbs heat when…


…it is subcooled
…it freezes
…it condenses
…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 to which the valve is filled with refrigerant liquid.
the degree of refrigerant expansion.

26

Stredne ťažká

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


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

27

Stredne ťažká

What does a thermostatic or electronic expansion valve control?


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

28

Stredne ťažká

What does the MOP function of thermostatic expansion valves mean?


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

30

Stredne ťažká

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


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

31

Stredne ťažká

What is the function of the suction pressure regulator?


It maintains the evaporation pressure at a constant level.
It limits the suction pressure and protects the compressor from excessively high suction pressure.
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.

32

Stredne ťažká

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


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


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

35

Stredne ťažká

When is refrigerant vapour superheated?


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

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

37

Stredne ťažká

Where does the liquid line run?


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

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 act as a reserve when the required charge is unknown
To store refrigerant and compensate for changes in the circulating charge as the heat load varies

39

Stredne ťažká

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


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

40

Stredne ťažká

Where should the liquid receiver be installed?


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

41

Stredne ťažká

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


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

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

43

Stredne ťažká

Which refrigerants belong to the HFC group?


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

44

Stredne ťažká

Which refrigerants belong to the HFO group?


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

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 R410A refrigerant is higher than that of R407C.
The saturation pressure of R407C refrigerant is much higher than that of R410A.
The saturation pressure of R407C is 150% 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 ability of the ozone layer to recover
The impact of a refrigerant on the ozone layer
The global warming potential of a gas relative to CO₂ over a 100-year horizon

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 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
It is a flammable and toxic single-component HFC

48

Stredne ťažká

What distinguishes R1234yf from R134a?


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

49

Stredne ťažká

How does CO₂ (R744) compare with R134a?


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

50

Stredne ťažká

Which of the following is NOT a fluorinated greenhouse gas?


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

51

Stredne ťažká

What is the greenhouse effect?


Clouds reflect ultraviolet radiation, which makes the air near the surface warmer
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

52

Ľahká

What does the GWP indicator mean?


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
The annual rise in mean air temperature caused by the emission of 1 kg of the gas

53

Stredne ťažká

How do refrigeration systems contribute to the greenhouse effect?


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

54

Stredne ťažká

What is the greenhouse effect?


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

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

56

Stredne ťažká

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


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

57

Stredne ťažká

What are the ecodesign obligations of manufacturers of refrigerating appliances?


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
Only declaring F-gas quantities under Regulation (EU) No 517/2014

58

Stredne ťažká

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


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

59

Stredne ťažká

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


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

60

Ľahká

What is the main function of a safety valve?


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

61

Stredne ťažká

How do certain gases contribute to the greenhouse effect?


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

62

Stredne ťažká

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


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

63

Stredne ťažká

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


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

64

Ťažká

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


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

65

Ťažká

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


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
It prevents liquid from entering the compressor

66

Stredne ťažká

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


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

67

Stredne ťažká

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


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

68

Stredne ťažká

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


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

69

Stredne ťažká

What is the role of defrost controls?


They monitor the moisture content of the refrigerant
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

70

Ľahká

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


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

71

Stredne ťažká

Where can the lists of fluorinated greenhouse gases be found?


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

72

Stredne ťažká

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


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 Annexes I and II to Regulation (EU) 2024/590 of the European Parliament and of the Council
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 cause rapid cooling of the atmosphere
They are climate- and environment-neutral
They are readily biodegradable
They are very persistent, accumulate in the environment (e.g. water) and may be toxic

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


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

76

Stredne ťažká

How does regular oil-level monitoring affect compressor operation?


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

77

Ľahká

How do system leaks affect compressor energy efficiency?


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

78

Stredne ťažká

Regulation (EU) 2024/590 relates to:


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

79

Stredne ťažká

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


The highest possible condensing pressure is best
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)
Pressures do not affect energy use

80

Stredne ťažká

Which maintenance measure reduces compressor energy consumption?


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

81

Stredne ťažká

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


It only affects the sight-glass indication
It lowers the condensing pressure
It improves condenser heat transfer
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 matter only in NH₃ systems
They increase the circulating refrigerant charge
They provide safety only, with no energy effect

83

Stredne ťažká

How does suction superheat at the compressor affect efficiency?


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

84

Stredne ťažká

How does correct system layout affect efficiency?


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

85

Stredne ťažká

How important is suction pipe insulation?


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

86

Stredne ťažká

Which measure most improves condenser energy efficiency?


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

87

Ľahká

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


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

88

Ľahká

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


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

89

Stredne ťažká

Which refrigerants damage the ozone layer?


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

90

Ľahká

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


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

91

Stredne ťažká

How does correct condensing pressure control affect efficiency?


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

92

Ľahká

How do condenser leaks affect energy efficiency?


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

93

Ľahká

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


It doesn’t matter
It should be close to heat sources
It should be installed in a well-ventilated area with unobstructed airflow
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 impairs cooling
It reduces energy losses and improves overall system efficiency
It increases pressure
It doesn't matter

96

Stredne ťažká

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


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

97

Ľahká

How does evaporator icing affect the system’s operation?


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

98

Ľahká

How does dirt on the evaporator surface affect its performance?


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

99

Ľahká

What maintenance task is crucial for the evaporator?


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

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)
Only leak checks that do not entail breaking into the refrigerant circuit
All activities involving equipment using CO₂ (R744)
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

101

Ľahká

How does superheat at the evaporator outlet affect efficiency?


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

102

Ľahká

How do leaks in the evaporator affect efficiency?


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

103

Ľahká

How important is correct expansion valve adjustment?


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

104

Ľahká

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


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

105

Ľahká

How does correct TEV adjustment affect system energy efficiency?


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

106

Ľahká

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


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

107

Stredne ťažká

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


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

108

Ľahká

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


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

109

Ľahká

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


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

110

Ľahká

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


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

111

Stredne ťažká

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


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

112

Ľahká

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


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

113

Ľahká

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


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

114

Stredne ťažká

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


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

115

Stredne ťažká

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


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

116

Stredne ťažká

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


The manufacturer's logo, the unit weight and year of manufacture from the rating plate
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 weight and capacity of the pipework and the colour code of the casing paint

117

Ľahká

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


°R
K
°C
°F

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?


All Schrader cores are suitable for all refrigerants
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

120

Ťažká

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


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


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

122

Stredne ťažká

Who is responsible for keeping the equipment records?


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

123

Ťažká

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


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

124

Stredne ťažká

Where are oil traps installed on the suction line?


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

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

126

Stredne ťažká

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


Sight glass full of liquid and rising oil level in the crankcase
Rising condensing and suction pressures with no superheat
Low suction pressure, high superheat and negligible subcooling
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 high-pressure-side components
Only suction-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 chosen by the technician based on experience
Always 30 bar
A pressure equal to the maximum pressure measured during operation

129

Stredne ťažká

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


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

130

Stredne ťažká

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


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

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

132

Ťažká

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


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

133

Ľahká

What is the superheat of refrigerant vapour?


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
The difference between the condensing temperature and the ambient temperature

134

Ťažká

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


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

135

Ťažká

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


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

136

Ťažká

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


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

137

Ťažká

Which leak-checking methods are considered direct methods?


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

138

Ťažká

What do indirect leak-checking methods involve?


Leak detection with an electronic detector
A visual and manual check and analysis of parameters: pressure, temperature, compressor current, liquid levels and recharge volume
Ultrasonic measurement
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
As quickly as possible
In any way

140

Stredne ťažká

What electronic equipment should be used for leak checking?


Only devices with an 'ion pump' sensor
Only detectors with an infrared sensor
Only hot-cathode devices
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
Only the installation invoice and the first start-up report
The operator's fixed-asset inventory ledger

142

Stredne ťažká

What information must be recorded in the leak check report?


The date, a general note about the leak and the operator's signature
Only the number of leaks found and the date of the check
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

143

Stredne ťažká

What pressure should be used for the pressure tightness test?


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

144

Stredne ťažká

What is the temperature glide of a refrigerant?


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

145

Ťažká

What does a vacuum (decay) test involve?


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

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)?


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

147

Ťažká

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


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

148

Stredne ťažká

In which equipment is a leakage detection system required?


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

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 charge is 100 kg or more of ozone-depleting substances
the equipment contains a flammable refrigerant in any quantity
the equipment operates in an enclosed space

150

Ťažká

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


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

151

Stredne ťažká

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


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

152

Stredne ťažká

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


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

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.
Between 24 hours and 1 month after the repair.
At the next periodic inspection.
Immediately 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 3 months
Every 12 months
Every month
Every 6 months

155

Stredne ťažká

Why is it advisable to subcool the liquid refrigerant?


To allow a condenser with a smaller heat-exchange surface to be used
To allow a smaller expansion valve to be used
To lower the evaporating temperature in the evaporator
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?


Visually inspect only the bolted and brazed joints near the repair
Charge an alternative refrigerant, start up and measure the parameters
Update the equipment records and carry out a leak check (it may be done directly after 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
The owner of the installation
A natural person holding a certificate of the relevant type (A1; A2. or D within their charge limit)

159

Stredne ťažká

How must recovered refrigerants be stored?


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

160

Stredne ťažká

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


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

161

Stredne ťažká

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


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


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

163

Stredne ťažká

How does push-pull refrigerant recovery work?


Nitrogen is injected into the system, pushing the refrigerant into the atmosphere
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
Refrigerant is drawn alternately from the suction and discharge sides of the compressor
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?


Storage
Destruction
Recycling
Reclamation

166

Stredne ťažká

The lower the evaporating temperature, …


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

167

Stredne ťažká

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


The marking is optional
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
With the manufacturer's logo and date of manufacture

168

Stredne ťažká

The recovery of refrigerants does not require the use of:


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

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 draws in refrigerant vapour from the evaporator, compresses it, and then forces it into the condenser, raising the pressure to the required condensing pressure.
The compressor compresses ambient air and increases the pressure of the refrigerant.

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 ratio of suction pressure to discharge pressure (po/pc)
The amount of refrigerant compressed per cycle relative to heat capacity
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
Excess oil in the condenser
Liquid refrigerant or oil entering the compression chamber
A large amount of liquid refrigerant in a flooded evaporator, which is a normal operating condition

172

Stredne ťažká

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


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

174

Stredne ťažká

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


Because these types of compressors are sensitive to voltage drops.
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 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
Greater than 10
Less than approximately 8
Equal to 1

176

Stredne ťažká

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


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

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

178

Stredne ťažká

Why is the compressor crankcase heated?


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

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

180

Stredne ťažká

What are compressor packs (racks)?


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

181

Stredne ťažká

What is the main advantage of multi-compressor packs?


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

182

Stredne ťažká

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


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

183

Stredne ťažká

What are the basic functions of oil in a compressor?


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

184

Stredne ťažká

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


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

185

Stredne ťažká

What does hot-gas bypass capacity control involve?


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

186

Stredne ťažká

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


The semi-hermetic casing is bolted (can be opened); the hermetic one is welded
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

187

Stredne ťažká

How does a scroll compressor work?


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

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 liquid refrigerant evaporates, absorbing heat, and the vapour is slightly superheated at the outlet
The refrigerant is subcooled as a liquid

189

Stredne ťažká

What is the purpose of compressor capacity control?


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

190

Stredne ťažká

Why is inverter speed control advantageous for refrigeration compressors?


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

191

Stredne ťažká

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


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

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.
No.
Only screw compressors.
Only scroll 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
Only a water–glycol mixture
Air or water

195

Stredne ťažká

What is the function of the condenser in refrigeration systems?


Absorption of heat rejected in the regenerative heat exchanger
Releasing to the environment the heat absorbed in the evaporator and the heat added during compression
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…


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

197

Stredne ťažká

How is liquid subcooling usually achieved in a refrigeration system?


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

198

Stredne ťažká

What is the purpose of condenser fan speed control?


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

199

Stredne ťažká

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


The Kyoto Protocol
The Vienna Convention for the Protection of the Ozone Layer
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 UN Framework Convention on Climate Change (UNFCCC)
The Paris Agreement
The Stockholm Convention
The Montreal Protocol

201

Ťažká

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


Each Member State sets its own GWP values
AR4 for all substances
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)

202

Ťažká

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


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

203

Ťažká

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


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

204

Ťažká

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


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

205

Ťažká

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


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

206

Ťažká

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


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

207

Stredne ťažká

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


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

208

Stredne ťažká

Who may purchase HFCs for servicing refrigeration equipment?


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

209

Stredne ťažká

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


Unconditionally
When the user signs a statement that they will install it themselves
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

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

211

Stredne ťažká

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


Nothing – Category I automatically becomes A1
Update their knowledge to the level of Certificate E
Update their knowledge and skills to the level of Certificate A1 (Annex I to Regulation 2024/2215)
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
Leak checks without breaking into the circuit
All activities in relation to CO₂
All activities in Article 2(1) in relation to ammonia (NH₃)

213

Stredne ťažká

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


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

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 1 year
At least 5 years
Until the equipment is decommissioned
At least 2 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
Yes – the ban applies from 2029
Yes – the ban applies only to units >12 kW
No – single splits <3 kg with F-gases of GWP ≥ 750 are banned

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

217

Ťažká

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


Ozone
Carbonic acid
Carbon dioxide
Trifluoroacetic acid (TFA)

218

Stredne ťažká

What is floating head pressure and what does it achieve?


It increases subcooling by flooding the condenser
It keeps a constant high condensing pressure all year
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)

219

Stredne ťažká

How do SEER/SCOP differ from EER/COP?


SEER/SCOP apply only to natural-refrigerant equipment
EER/COP are always higher than SEER/SCOP
There is no difference – they are synonyms
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?


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

221

Stredne ťažká

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


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

222

Stredne ťažká

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


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