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

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 compressor pushes heat directly into 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

4

Medium

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


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

5

Medium

What criteria should be considered when selecting a suitable condenser?


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

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 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.
Contaminants increase the heat transfer area and reduce the condensing pressure.

7

Medium

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


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

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
A rise in evaporating pressure
An increase in condenser subcooling
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 discharge temperature decreases.
The compressor’s cooling capacity increases.
The condenser fan speed increases.

10

Medium

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


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

11

Medium

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


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

12

Medium

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


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

13

Medium

How does hot gas defrosting of the evaporator work?


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

14

Medium

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


It cools the refrigerant.
It evaporates the water flowing through the evaporator.
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.

15

Medium

What condition must electric heaters for evaporator defrosting meet?


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

16

Medium

Refrigerant distributor:


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.
ensures the even distribution of the refrigerant discharged by compressors connected in parallel.

17

Medium

What defrosting methods are used for air coolers?


Natural only – other methods are ineffective and uneconomic
Electric, hot gas, water spray and natural (at positive temperatures)
Electric only – other methods are not permitted in refrigeration
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
…remains constant
…varies depending on the ambient temperature

19

Medium

MOP in thermostatic expansion valves stands for:


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

20

Medium

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


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

21

Medium

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


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

22

Medium

What does a thermostatic expansion valve control?


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

23

Medium

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


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

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

25

Medium

What does a thermostatic or electronic expansion valve control?


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

26

Medium

What does the MOP function of thermostatic expansion valves mean?


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
The valve maintains a constant condensing pressure
The valve limits subcooling

27

Medium

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


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

28

Medium

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


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

29

Medium

What is the function of the suction pressure regulator?


It prevents a drop in suction pressure and, if necessary, shuts down the refrigeration system.
It limits the suction pressure and protects the compressor from excessively high suction pressure.
To maintain the suction pressure at the highest possible level.
It maintains the evaporation pressure at a constant 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 internal pressure equalisation.
... with an adsorption-type sensor filling.
... with a MOP function.
... with external pressure equalisation.

32

Medium

What properties should good insulation materials have?


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

33

Medium

When is refrigerant vapour superheated?


When the compressor motor temperature rises excessively
When its temperature is higher than the saturation temperature corresponding to its pressure
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 are unable to check this.
We check this using a sight glass.
We check using a liquid pressure gauge.
We check using a pressure gauge fitted on the discharge side of the compressor.

35

Medium

Where does the liquid line run?


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

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 further subcool the condensed refrigerant
To collect liquid refrigerant and excess oil
To act as a reserve when the required charge is unknown

37

Medium

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


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

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 regulates the condensing pressure.
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.

40

Medium

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


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

41

Medium

Which refrigerants belong to the HFC group?


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

42

Medium

Which refrigerants belong to the HFO group?


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

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

44

Medium

What does the TEWI indicator define?


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

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 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
Unlike R134a, it is an azeotropic mixture

48

Medium

Which of the following is NOT a fluorinated greenhouse gas?


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

49

Medium

What is the greenhouse effect?


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
Chlorine compounds destroy stratospheric ozone, increasing UV radiation at the surface

50

Medium

What is R1270?


Isobutane
Propane
n-Butane
Propene (propylene)

51

Medium

How do refrigeration systems contribute to the greenhouse effect?


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

52

Medium

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 trapping of heat in the Earth's atmosphere, which hinders the radiation of heat into space
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?


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

54

Medium

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


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

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

57

Medium

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

58

Medium

How do certain gases contribute to the greenhouse effect?


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

59

Medium

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


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

60

Medium

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


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

61

Medium

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


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

62

Medium

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 regulates the oil returning to the compressor
It stores refrigerant; checking its liquid level helps detect charge loss
It controls the evaporating temperature by varying the circulating charge

63

Medium

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


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

64

Medium

What is the role of defrost controls?


They protect the evaporator from icing and damage that could lead to leaks
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

65

Medium

Where can the lists of fluorinated greenhouse gases be found?


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

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 is colourless and odourless and therefore hard to detect
Because it does not react with water, making neutralisation difficult
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 31 March, electronically to the Ministry of Climate and Environment
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)

69

Medium

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


Omitting the filter-drier to reduce flow resistance
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)

70

Medium

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 allows the crankcase heater to be omitted
It ensures proper lubrication and limits wear and energy losses

71

Medium

Regulation (EU) 2024/590 relates to:


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

72

Medium

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


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

73

Medium

Which maintenance measure reduces compressor energy consumption?


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
Topping up refrigerant at every service visit

74

Medium

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


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

75

Medium

What role do controls play in compressor efficiency?


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

76

Medium

How does suction superheat at the compressor affect efficiency?


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

77

Medium

How does correct system layout affect efficiency?


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

78

Medium

How important is suction pipe insulation?


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

79

Medium

Which measure most improves condenser energy efficiency?


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

80

Medium

Which refrigerants damage the ozone layer?


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

81

Medium

How does correct condensing pressure control affect efficiency?


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

82

Medium

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


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

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
Raising the condensing temperature by a few kelvin
Increasing the refrigerant charge above nominal

84

Medium

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


Only leak checks that do not entail breaking into the refrigerant circuit
Only recovery of F-gases from equipment containing less than 3 kg (or 6 kg in hermetically sealed systems)
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 has no effect
It may lead to improved efficiency, but it increases the risk of the compressor becoming flooded with liquid
It reduces refrigerant flow
It increases operational safety

86

Medium

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


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

87

Medium

What is the main design difference in hydrocarbon refrigeration systems?


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

88

Medium

How do compressors used in hydrocarbon systems differ?


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

89

Medium

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
Under normal operating conditions the condensing pressure and subcooling rise markedly because excess liquid floods the condenser and reduces its active surface
It cannot be checked, because the sight glass is not intended for this

90

Medium

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


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

91

Medium

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
The weight and capacity of the pipework and the colour code of the casing paint
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?


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

93

Medium

Who is responsible for keeping the equipment records?


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

94

Medium

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
Immediately before the compressor suction connection
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
Sight glass full of liquid and rising oil level in the crankcase
Rising condensing and suction pressures with no superheat
Rising liquid level in the receiver and increasing subcooling

96

Medium

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


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

97

Medium

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


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

98

Medium

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


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

99

Medium

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


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

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?


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

101

Medium

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


As quickly as possible
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

102

Medium

What electronic equipment should be used for leak checking?


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

103

Medium

What documentation should be checked before starting a leak check?


The operator's fixed-asset inventory ledger
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

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
The method used, the time spent on site and the cost of repair
Date, number and location of leaks, how they were repaired, technician details and signature
Only the number of leaks found and the date of the check

105

Medium

What pressure should be used for the pressure tightness test?


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

106

Medium

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
A property of single-component refrigerants, for which one saturation temperature corresponds to a given pressure
The temperature drop of the refrigerant across the expansion valve
The temperature rise of the vapour in the compressor

107

Medium

In which equipment is a leakage detection system required?


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

108

Medium

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


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

109

Medium

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


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

110

Medium

Why is it advisable to subcool the liquid refrigerant?


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

111

Medium

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
Issue the invoice and leave the leak check to the next periodic service
Update the equipment records and carry out a leak check (it may be done directly after repair)

112

Medium

Recovery of fluorinated greenhouse gases means:


The reprocessing of fluorinated greenhouse gases to achieve their specified standard properties.
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 final decommissioning and withdrawal from service or use of a product or piece of equipment containing fluorinated greenhouse gases.

113

Medium

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


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

114

Medium

How must recovered refrigerants be stored?


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
In any pressure vessel that has some form of approval

115

Medium

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


Before the final disposal of equipment and, where applicable, during its servicing and maintenance.
Before each leak test of the equipment.
Always during servicing and maintenance of 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)?


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

117

Medium

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


Separate the mixture into its components yourself
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

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

119

Medium

What are the options for managing waste refrigerant?


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

120

Medium

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


Reclamation
Storage
Destruction
Recycling

121

Medium

The lower the evaporating temperature, …


…the greater 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
…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

122

Medium

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


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

123

Medium

The recovery of refrigerants does not require the use of:


An electronic leak detector.
A refrigerant recovery station.
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 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.
The compressor condenses the refrigerant.

125

Medium

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

126

Medium

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


From approximately 10% to 90% of nominal capacity
By a maximum of 10%
Speed control does not change the cooling capacity
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 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.

128

Medium

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


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

129

Medium

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


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

130

Medium

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
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

131

Medium

Why is the compressor crankcase heated?


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

132

Medium

What are compressor packs (racks)?


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

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 by the evaporating temperature at a given ambient temperature
A range determined only by the evaporating temperature
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

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?


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

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

138

Medium

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


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

139

Medium

How does a scroll compressor work?


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

140

Medium

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

141

Medium

What is the purpose of compressor capacity control?


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

142

Medium

Why is inverter speed control advantageous for refrigeration compressors?


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

143

Medium

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


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

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?


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

145

Medium

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.
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.
The compressor compresses ambient air and increases the pressure of the refrigerant.

146

Medium

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


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

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 from the compressor into the surroundings
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

148

Medium

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


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

149

Medium

How is liquid subcooling usually achieved in a refrigeration system?


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

150

Medium

What is the purpose of condenser fan speed control?


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

151

Medium

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


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

153

Medium

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


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

154

Medium

Who may purchase HFCs for servicing refrigeration equipment?


Only a person holding the relevant certificate or an undertaking employing such persons
Only the equipment operator
Any adult
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 the user signs a statement that they will install it themselves
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

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 12 March 2025
Never – the certificate is valid indefinitely
By 31 December 2030
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?


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

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
Leak checks without breaking into the circuit
All activities in Article 2(1) in relation to ammonia (NH₃)

159

Medium

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


Yes – under the supervision of a certified person, for no more than 24 months in total
No, never
Yes – with no time limit, if employed by a certified company
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 5 years
Until the equipment is decommissioned
At least 1 year
At least 2 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. 0.038 kg/m³ (approx. 2.1% by volume)
Approx. 0.307 kg/m³
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)
20 (dusts)
0
1

164

Medium

How is explosion hazard zone 2 defined?


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

165

Medium

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


UN 3337
UN 1005
UN 3252
UN 1978

166

Medium

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


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

167

Medium

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


Purge it with compressed air
Evacuate it (no air) and label it for the specific flammable refrigerant
Partly fill it with nitrogen to 5 bar
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 eliminate hazard sources (e.g. ignition sources); where this is not possible, identify them and apply mitigating measures (ventilation, detection, PPE)
First select PPE, then possibly remove ignition sources
Having a fire extinguisher is sufficient

169

Medium

Which property of ammonia helps people detect a leak early?


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

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
Formation of hydrogen fluoride
Accumulation near the floor and asphyxiating/toxic effects at high concentrations

171

Medium

What is floating head pressure and what does it achieve?


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

172

Medium

How do SEER/SCOP differ from EER/COP?


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
SEER/SCOP apply only to natural-refrigerant equipment
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
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

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 extra R290 improves efficiency
Because R290 is more expensive than HFCs
Because scales are not needed – charging is done by sight glass

175

Medium

Which information must be entered in the equipment records after a leak 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)
Only the operator's signature
Only the date of the check

176

Medium

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


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