Testy

F-Gas English Low GWP

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

1

Stredne ťažká

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


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

2

Stredne ťažká

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


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

3

Stredne ťažká

Why does heat flow from the condenser to the surroundings?


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

4

Stredne ťažká

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


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

5

Stredne ťažká

What criteria should be considered when selecting a suitable condenser?


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

6

Stredne ťažká

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


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

7

Stredne ťažká

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


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

8

Stredne ťažká

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
Reduced heat transfer and airflow, resulting in a drop in cooling capacity and evaporating temperature
An increase in condenser subcooling

9

Stredne ťažká

What happens when the evaporation temperature drops?


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

10

Stredne ťažká

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


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

11

Stredne ťažká

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


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

12

Stredne ťažká

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


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

13

Stredne ťažká

How does hot gas defrosting of the evaporator work?


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

14

Stredne ťažká

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

Stredne ťažká

What condition must electric heaters for evaporator defrosting meet?


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

16

Stredne ťažká

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 the even distribution of the refrigerant discharged by compressors connected in parallel.
ensures even distribution of the refrigerant to the individual sections of the condenser.

17

Stredne ťažká

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
Only by switching off the fans with the compressor running
Natural only – other methods are ineffective and uneconomic

18

Stredne ťažká

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


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

19

Stredne ťažká

MOP in thermostatic expansion valves stands for:


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

20

Stredne ťažká

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


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
to adjust the evaporating pressure in the condenser

21

Stredne ťažká

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


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

22

Stredne ťažká

What does a thermostatic expansion valve control?


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

23

Stredne ťažká

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


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

24

Stredne ťažká

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


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

25

Stredne ťažká

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

Stredne ťažká

What does the MOP function of thermostatic expansion valves mean?


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

27

Stredne ťažká

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


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

28

Stredne ťažká

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


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

29

Stredne ťažká

What is the function of the suction pressure regulator?


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

30

Stredne ťažká

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


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

31

Stredne ťažká

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


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

32

Stredne ťažká

What properties should good insulation materials have?


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

33

Stredne ťažká

When is refrigerant vapour superheated?


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

34

Stredne ťažká

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

Stredne ťažká

Where does the liquid line run?


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

36

Stredne ťažká

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


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

37

Stredne ťažká

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


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

38

Stredne ťažká

Where should the liquid receiver be installed?


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

39

Stredne ťažká

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

40

Stredne ťažká

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


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

41

Stredne ťažká

Which refrigerants belong to the HFC group?


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

42

Stredne ťažká

Which refrigerants belong to the HFO group?


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

43

Stredne ťažká

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


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

44

Stredne ťažká

What does the TEWI indicator define?


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

45

Stredne ťažká

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

46

Stredne ťažká

What distinguishes R1234yf from R134a?


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

47

Stredne ťažká

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)
Unlike R134a, it is an azeotropic mixture
It has identical properties and is a drop-in replacement for R134a

48

Stredne ťažká

Which of the following is NOT a fluorinated greenhouse gas?


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

49

Stredne ťažká

What is the greenhouse effect?


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

50

Stredne ťažká

How do refrigeration systems contribute to the greenhouse effect?


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

51

Stredne ťažká

What is the greenhouse effect?


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

52

Stredne ťažká

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


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

53

Stredne ťažká

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

54

Stredne ťažká

What are the ecodesign obligations of manufacturers of refrigerating appliances?


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

55

Stredne ťažká

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


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

56

Stredne ťažká

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


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

57

Stredne ťažká

How do certain gases contribute to the greenhouse effect?


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

58

Stredne ťažká

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


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

59

Stredne ťažká

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


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

60

Stredne ťažká

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


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

61

Stredne ťažká

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


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

62

Stredne ťažká

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


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

63

Stredne ťažká

What is the role of defrost controls?


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

64

Stredne ťažká

Where can the lists of fluorinated greenhouse gases be found?


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

65

Stredne ťažká

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


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

66

Stredne ťažká

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


By 31 January, in the Central Register of Operators (CRO)
By 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 the end of the calendar year, on a form at a regional office of the Office of Technical Inspection (UDT)

67

Stredne ťažká

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


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
Installing a suction line smaller than recommended

68

Stredne ťažká

How does regular oil-level monitoring affect compressor operation?


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

69

Stredne ťažká

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

70

Stredne ťažká

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


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

71

Stredne ťažká

Which maintenance measure reduces compressor energy consumption?


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

72

Stredne ťažká

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


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

73

Stredne ťažká

What role do controls play in compressor efficiency?


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

74

Stredne ťažká

How does suction superheat at the compressor affect efficiency?


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

75

Stredne ťažká

How does correct system layout affect efficiency?


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

76

Stredne ťažká

How important is suction pipe insulation?


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

77

Stredne ťažká

Which measure most improves condenser energy efficiency?


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

78

Stredne ťažká

Which refrigerants damage the ozone layer?


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

79

Stredne ťažká

How does correct condensing pressure control affect efficiency?


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

80

Stredne ťažká

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


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

81

Stredne ťažká

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

82

Stredne ťažká

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

83

Stredne ťažká

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 has no effect
It reduces refrigerant flow
It increases operational safety

84

Stredne ťažká

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


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

85

Stredne ťažká

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
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

86

Stredne ťažká

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


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

87

Stredne ťažká

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


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

88

Stredne ťažká

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


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

89

Stredne ťažká

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.

90

Stredne ťažká

Where are oil traps installed on the suction line?


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

91

Stredne ťažká

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


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

92

Stredne ťažká

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


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

93

Stredne ťažká

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


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

94

Stredne ťažká

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


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

95

Stredne ťažká

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


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
When gas bubbles appear after immersion in water

96

Stredne ťažká

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


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

97

Stredne ťažká

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


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

98

Stredne ťažká

What electronic equipment should be used for leak checking?


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

99

Stredne ťažká

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
Attendance sheets of the plant-room staff for the year
The operator's fixed-asset inventory ledger

100

Stredne ťažká

What information must be recorded in the leak check report?


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

101

Stredne ťažká

What pressure should be used for the pressure tightness test?


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

102

Stredne ťažká

What is the temperature glide of a refrigerant?


The temperature rise of the vapour in the compressor
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
In zeotropic mixtures, the difference between the temperatures at the start and end of a phase change (boiling or condensation) at constant pressure

103

Stredne ťažká

In which equipment is a leakage detection system required?


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

104

Stredne ťažká

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


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

105

Stredne ťažká

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 E
Only A1 and A2

106

Stredne ťažká

Why is it advisable to subcool the liquid refrigerant?


To allow a condenser with a smaller heat-exchange surface to be used
To 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

107

Stredne ťažká

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


Visually inspect only the bolted and brazed joints near the repair
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
Charge an alternative refrigerant, start up and measure the parameters

108

Stredne ťažká

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 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.

109

Stredne ťažká

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


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

110

Stredne ťažká

How must recovered refrigerants be stored?


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

111

Stredne ťažká

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


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

112

Stredne ťažká

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

113

Stredne ťažká

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


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

114

Stredne ťažká

How does push-pull refrigerant recovery work?


Nitrogen is injected into the system, pushing the refrigerant into the atmosphere
The recovery unit draws vapour from the system and condenses it in the cylinder
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

115

Stredne ťažká

What are the options for managing waste refrigerant?


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

116

Stredne ťažká

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


Storage
Reclamation
Destruction
Recycling

117

Stredne ťažká

The lower the evaporating temperature, …


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

118

Stredne ťažká

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


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

119

Stredne ťažká

The recovery of refrigerants does not require the use of:


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

120

Stredne ťažká

What functions does the compressor perform in a refrigeration system?


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

121

Stredne ťažká

What is compressor flooding (liquid slugging)?


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

122

Stredne ťažká

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


From approximately 10% to 90% of nominal capacity
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)
By a maximum of 10%

123

Stredne ťažká

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


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

124

Stredne ťažká

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


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

125

Stredne ťažká

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


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

126

Stredne ťažká

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

127

Stredne ťažká

Why is the compressor crankcase heated?


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

128

Stredne ťažká

What are compressor packs (racks)?


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

129

Stredne ťažká

What is the main advantage of multi-compressor packs?


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

130

Stredne ťažká

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


A range determined only by the evaporating temperature
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
The capacity, refrigerant type and dimensions of the compressor

131

Stredne ťažká

What are the basic functions of oil in a compressor?


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

132

Stredne ťažká

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


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

133

Stredne ťažká

What does hot-gas bypass capacity control involve?


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

134

Stredne ťažká

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


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

135

Stredne ťažká

How does a scroll compressor work?


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

136

Stredne ťažká

What physical process takes place in the evaporator?


The refrigerant is subcooled as a liquid
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

137

Stredne ťažká

What is the purpose of compressor capacity control?


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

138

Stredne ťažká

Why is inverter speed control advantageous for refrigeration compressors?


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

139

Stredne ťažká

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


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

140

Stredne ťažká

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


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

141

Stredne ťažká

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.

142

Stredne ťažká

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


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

143

Stredne ťažká

What is the function of the condenser in refrigeration systems?


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

144

Stredne ťažká

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


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

145

Stredne ťažká

How is liquid subcooling usually achieved in a refrigeration system?


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

146

Stredne ťažká

What is the purpose of condenser fan speed control?


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

147

Stredne ťažká

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


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

148

Stredne ťažká

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


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

149

Stredne ťažká

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


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

150

Stredne ťažká

Who may purchase HFCs for servicing refrigeration equipment?


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

151

Stredne ťažká

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


Only if the unit contains less than 3 kg of refrigerant
Unconditionally
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

152

Stredne ťažká

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


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

153

Stredne ťažká

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

154

Stredne ťažká

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


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

155

Stredne ťažká

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


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

156

Stredne ťažká

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


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

157

Stredne ťažká

What is floating head pressure and what does it achieve?


It means switching condenser fans off periodically
It keeps a constant high condensing pressure all year
It increases subcooling by flooding the condenser
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)

158

Stredne ťažká

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

159

Stredne ťažká

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


Omitting pipe insulation
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
Larger liquid-line diameters

160

Stredne ťažká

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


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

161

Stredne ťažká

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


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