Tests

F-Gas English Low GWP

All questions
HFC | Flammable | CO₂ | NH₃
Easy questions | Medium questions | Difficult questions

1

Medium

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


The secondary fluid (glycol, water) condenses while the refrigerant 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
The refrigerant absorbs heat from the surroundings and evaporates

2

Medium

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


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

3

Medium

Why does heat flow from the condenser to 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 compressor pushes heat directly into the surroundings
Because the pressure in the condenser is lower than ambient

4

Medium

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


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

5

Medium

What criteria should be considered when selecting a suitable condenser?


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

6

Medium

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 a reduction in condensing pressure.
Contaminants increase the heat transfer area and reduce the condensing pressure.
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 an increase in condensing temperature and pressure, which in turn leads to a reduction in the condenser’s efficiency.

7

Medium

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


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

8

Medium

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


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

9

Medium

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.

10

Medium

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


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

11

Medium

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


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

12

Medium

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
…using smaller-diameter pipes
…additional subcooling of the liquid
…increasing the length of the liquid line

13

Medium

How does hot gas defrosting of the evaporator work?


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.
We switch on the gas heater directed at the evaporator.

14

Medium

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


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

15

Medium

What condition must electric heaters for evaporator defrosting meet?


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
Heat from the heaters must be carried by the running fans

16

Medium

Refrigerant distributor:


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

17

Medium

What defrosting methods are used for air coolers?


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

18

Medium

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


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

19

Medium

MOP in thermostatic expansion valves stands for:


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

20

Medium

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


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

21

Medium

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


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

22

Medium

What does a thermostatic expansion valve control?


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

23

Medium

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


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

24

Medium

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


In the liquid phase on the high-pressure side, with the compressor stopped
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

25

Medium

What does a thermostatic or electronic expansion valve control?


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

26

Medium

What does the MOP function of thermostatic expansion valves mean?


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

27

Medium

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


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

28

Medium

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


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

29

Medium

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.

30

Medium

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

31

Medium

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


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

32

Medium

What properties should good insulation materials have?


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

33

Medium

When is refrigerant vapour superheated?


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

34

Medium

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


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

35

Medium

Where does the liquid line run?


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

36

Medium

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


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

37

Medium

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


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

38

Medium

Where should the liquid receiver be installed?


It should be fitted after the evaporator.
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.

39

Medium

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

40

Medium

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


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

41

Medium

Which refrigerants belong to the HFC group?


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

42

Medium

Which refrigerants belong to the HFO group?


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

43

Medium

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


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

44

Medium

What does the TEWI indicator define?


The global warming potential of a gas relative to CO₂ over a 100-year horizon
The ability of the ozone layer to recover
The impact of a refrigerant on the ozone layer
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

45

Medium

What are the characteristics of R452A compared with 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
The temperature glide of R452A is half that of R404A
It is a flammable and toxic single-component HFC

46

Medium

What distinguishes R1234yf from R134a?


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

47

Medium

How does CO₂ (R744) compare with R134a?


Its temperature glide is 7 K greater than that of 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

48

Medium

Which of the following is NOT a fluorinated greenhouse gas?


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

49

Medium

What is the greenhouse effect?


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

50

Medium

What is R1270?


Isobutane
Propane
n-Butane
Propene (propylene)

51

Medium

How do refrigeration systems contribute to the greenhouse effect?


Indirectly (through energy consumption) and directly (through emissions of refrigerant into the atmosphere)
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

52

Medium

What is the greenhouse effect?


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

53

Medium

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

54

Medium

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


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

55

Medium

What are the ecodesign obligations of manufacturers of refrigerating appliances?


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

56

Medium

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

57

Medium

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
Enables the refrigerant flow to be completely shut off
It regulates the temperature of the refrigerant

58

Medium

How do certain gases contribute to the greenhouse effect?


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

59

Medium

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


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

60

Medium

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


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

61

Medium

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


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

62

Medium

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


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

63

Medium

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


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

64

Medium

What is the role of defrost controls?


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

65

Medium

Where can the lists of fluorinated greenhouse gases be found?


In the Vienna Convention for the Protection of the Ozone Layer
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
In a regulation of the Minister of Economy on the list of fluorinated greenhouse gases

66

Medium

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


In the national Act on ozone-depleting substances and certain fluorinated greenhouse gases
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 Vienna Convention for the Protection of the Ozone Layer

67

Medium

Why is ammonia (R717) classed as a toxic refrigerant?


It severely irritates the respiratory tract, eyes and skin, and is poisonous when inhaled at higher concentrations
Because it does not react with water, making neutralisation difficult
Because it is colourless and odourless and therefore hard to detect
Because it is heavier than air and displaces oxygen

68

Medium

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 March, electronically to the Ministry of Climate and Environment
By 31 January, in the Central Register of Operators (CRO)

69

Medium

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


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

70

Medium

How does regular oil-level monitoring affect compressor operation?


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

71

Medium

Regulation (EU) 2024/590 relates to:


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

72

Medium

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


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

73

Medium

Which maintenance measure reduces compressor energy consumption?


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

74

Medium

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


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

75

Medium

What role do controls play in compressor efficiency?


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

76

Medium

How does suction superheat at the compressor affect efficiency?


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

77

Medium

How does correct system layout affect efficiency?


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

78

Medium

How important is suction pipe insulation?


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

79

Medium

Which measure most improves condenser energy efficiency?


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

80

Medium

Which refrigerants damage the ozone layer?


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

81

Medium

How does correct condensing pressure control affect efficiency?


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

82

Medium

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


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

83

Medium

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


Restricting the airflow through the 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

84

Medium

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

85

Medium

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


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

86

Medium

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


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

87

Medium

What is the main design difference in hydrocarbon refrigeration systems?


No need for safety measures
Higher operating pressures
Lower energy efficiency
The need to eliminate ignition sources and limit the charge because of the refrigerant's flammability

88

Medium

How do compressors used in hydrocarbon systems differ?


They must operate at higher pressures than HFC compressors
They need no lubrication
There is no difference
They must be approved by the manufacturer for the specific flammable refrigerant (e.g. electrical components that are not ignition sources, suitable oil)

89

Medium

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


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
Under normal operating conditions the condensing pressure and subcooling rise markedly because excess liquid floods the condenser and reduces its active surface

90

Medium

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


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

91

Medium

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


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

92

Medium

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


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

93

Medium

Who is responsible for keeping the equipment records?


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

94

Medium

Where are oil traps installed on the suction line?


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

95

Medium

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


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

96

Medium

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


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

97

Medium

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


Always 30 bar
A pressure equal to the maximum pressure measured during operation
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

98

Medium

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

99

Medium

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


When gas bubbles appear after immersion in water
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 it has been checked with a fixed electronic detector

100

Medium

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

101

Medium

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

102

Medium

What electronic equipment should be used for leak checking?


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

103

Medium

What documentation should be checked before starting a leak check?


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
Attendance sheets of the plant-room staff for the year

104

Medium

What information must be recorded in the leak check report?


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

105

Medium

What pressure should be used for the pressure tightness test?


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

106

Medium

What is the temperature glide of a refrigerant?


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
In zeotropic mixtures, the difference between the temperatures at the start and end of a phase change (boiling or condensation) at constant pressure

107

Medium

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 30 kg or more of F-gases, regardless of their GWP
Equipment with 5 t CO₂ eq or more of F-gases, regardless of equipment type

108

Medium

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

109

Medium

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 A1 and A2
Only E

110

Medium

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

111

Medium

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


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
Visually inspect only the bolted and brazed joints near the repair

112

Medium

Recovery of fluorinated greenhouse gases means:


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

113

Medium

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


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
The administrator of the operator's account in the register

114

Medium

How must recovered refrigerants be stored?


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

115

Medium

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


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

116

Medium

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


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
Add a special contaminant neutraliser

117

Medium

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
Pass it through a filter-drier and reuse it
Separate the mixture into its components yourself
Add a special refrigerant to the mixture

118

Medium

How does push-pull refrigerant recovery work?


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
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

119

Medium

What are the options for managing waste refrigerant?


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

120

Medium

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


Destruction
Reclamation
Recycling
Storage

121

Medium

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

122

Medium

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


With the manufacturer's logo and date of manufacture
The marking is optional
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
Only with weight and capacity marks

123

Medium

The recovery of refrigerants does not require the use of:


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

124

Medium

What functions does the compressor perform in a refrigeration 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.
The compressor condenses the refrigerant.
The compressor creates a vacuum on the suction side of the system

125

Medium

What is compressor flooding (liquid slugging)?


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

126

Medium

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


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

127

Medium

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


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

128

Medium

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


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

129

Medium

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


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

130

Medium

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


Check whether the whole evaporator surface is covered with an even layer of frost
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 liquid distributor upstream of the evaporator feels warm

131

Medium

Why is the compressor crankcase heated?


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

132

Medium

What are compressor packs (racks)?


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

133

Medium

What is the main advantage of multi-compressor packs?


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

134

Medium

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


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

135

Medium

What are the basic functions of oil in a compressor?


Absorbing moisture from 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)
Increasing the cooling capacity of the refrigerant

136

Medium

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


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

137

Medium

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
Bypass is not used for capacity control
The compressor speed is varied
High-pressure liquid is injected into the suction to increase capacity

138

Medium

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

139

Medium

How does a scroll compressor work?


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

140

Medium

What physical process takes place in the evaporator?


The refrigerant condenses
The secondary fluid (glycol, water) evaporates while 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

141

Medium

What is the purpose of compressor capacity control?


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

142

Medium

Why is inverter speed control advantageous for refrigeration compressors?


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

143

Medium

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


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

144

Medium

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


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

145

Medium

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


This compressor creates a vacuum on the suction side of the system whilst the vehicle’s engine is switched off.
The compressor compresses ambient air and increases the pressure of the refrigerant.
This compressor condenses the refrigerant whilst the vehicle is in motion.
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.

146

Medium

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


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

147

Medium

What is the function of the condenser in refrigeration systems?


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

148

Medium

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


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

149

Medium

How is liquid subcooling usually achieved in a refrigeration system?


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

150

Medium

What is the purpose of condenser fan speed control?


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

151

Medium

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


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

152

Medium

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


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

153

Medium

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, always
Yes, if less than 24 hours have passed

154

Medium

Who may purchase HFCs for servicing refrigeration equipment?


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

155

Medium

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


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

156

Medium

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

157

Medium

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


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

158

Medium

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


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

159

Medium

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


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
Yes – independently, for 6 months

160

Medium

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 2 years
Until the equipment is decommissioned
At least 5 years

161

Medium

What distinguishes class 2L refrigerants from class 2?


No lower flammability limit
A maximum burning velocity of no more than 10 cm/s
Higher toxicity
Heat of combustion above 19 MJ/kg

162

Medium

What is the lower flammability limit (LFL) of propane R290?


Approx. 0.307 kg/m³
Approx. 0.038 kg/m³ (approx. 2.1% by volume)
Approx. 1.8 kg/m³
Approx. 0.38 kg/m³

163

Medium

Equipment marked 'Ex II 3G' may be used in zone:


2 (explosive gas atmosphere unlikely and short-lived)
1
20 (dusts)
0

164

Medium

How is explosion hazard zone 2 defined?


An explosive atmosphere is present continuously or for long periods
An explosive atmosphere is not likely in normal operation and, if it occurs, persists only for a short period
An explosive atmosphere is likely to occur in normal operation
An area where flammable refrigerants are never used

165

Medium

Under which UN number is propane (R290) carried under ADR?


UN 1005
UN 1978
UN 3337
UN 3252

166

Medium

At what concentration should a portable flammable gas detector used for R290 work raise an alarm at the latest?


No higher than 25% of LFL
At 150% of LFL
At 100% of LFL
At 5% propane by volume

167

Medium

How should a recovery cylinder be prepared before filling it with a hydrocarbon refrigerant?


Evacuate it (no air) and label it for the specific flammable refrigerant
Partly fill it with nitrogen to 5 bar
Purge it with compressed air
No preparation is needed

168

Medium

What is the correct approach in a risk analysis before work on an HC system?


The risk analysis is done after the work is finished
First select PPE, then possibly remove ignition sources
First eliminate hazard sources (e.g. ignition sources); where this is not possible, identify them and apply mitigating measures (ventilation, detection, PPE)
Having a fire extinguisher is sufficient

169

Medium

Which property of ammonia helps people detect a leak early?


It is denser than air
It is yellow in air
It is odourless
A very low odour threshold (a few ppm)

170

Medium

What hazard does a large CO₂ leak in an enclosed room pose to people?


Explosion of the mixture with air
CO₂ is completely safe
Accumulation near the floor and asphyxiating/toxic effects at high concentrations
Formation of hydrogen fluoride

171

Medium

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 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 means switching condenser fans off periodically

172

Medium

How do SEER/SCOP differ from EER/COP?


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

173

Medium

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


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

174

Medium

Why must the charge of small, critically charged R290 systems be weighed to within a few grams during service?


Small charge deviations significantly change superheat/subcooling and efficiency, and overcharge increases the risk in a leak
Because R290 is more expensive than HFCs
Because scales are not needed – charging is done by sight glass
Because extra R290 improves efficiency

175

Medium

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


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

176

Medium

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


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