Testy

F-Gas English Low GWP

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

1

Ľahká

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


kg
Pound
N
t

2

Stredne ťažká

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


In the condenser, the refrigerant releases the heat absorbed in the evaporator into the surroundings.
The medium flowing through the evaporator (glycol, water) condenses, whilst the refrigerant evaporates.
The refrigerant releases the heat absorbed in the compressor via the condenser
Hot refrigerant vapour is pumped from the compressor to the condenser, where it is cooled and then condensed. In this heat exchanger, the resulting liquid refrigerant is also slightly subcooled.

3

Stredne ťažká

What determines the condensation temperature of an air-cooled unit?


On the superheat temperature.
On the evaporation (boiling) temperature.
On the ambient temperature.
On the compressor and discharge temperatures

4

Stredne ťažká

Is energy required when heat is transferred from the condenser to the surroundings?


The heat flow balances the energy input.
Yes, in every case.
No, because according to the second law of thermodynamics, thermal energy always flows from a body at a higher temperature to a body at a lower temperature.
Yes, but only when using HFC refrigerants.

5

Stredne ťažká

What should you pay attention to during the operation of the condenser?


You should ensure the general maintenance of the condenser and keep the heat exchange surfaces clean.
Ensure that the air temperature at the condenser outlet is higher than the condensation temperature.
Pay attention to the fan’s operation and the ambient temperature.
Care should be taken to ensure that the air temperature at the condenser inlet is lower than the air temperature at the condenser outlet.

6

Stredne ťažká

What criteria should be considered when selecting a suitable condenser?


First and foremost, you should consider the operating noise level of the fans, the diameter of the connection pipes and the colour scheme.
These include size and the number of fans. The geometric parameters of the condenser must be taken into account.
The required capacity of the condenser and the technical specifications declared by the manufacturer must be taken into account.
Condensers should be selected based on your own experience, and the condenser’s geometric parameters should be taken into account.

7

Stredne ťažká

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


Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause 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.

8

Stredne ťažká

If an air-cooled condenser becomes contaminated, will the condensation efficiency?


It remains unchanged.
It will increase as a result of the fan speed being raised further.
It will increase.
It will decrease.

9

Stredne ťažká

What can cause frost to form on the evaporator?


a drop in cooling capacity.
An increase in refrigerant flow resistance and a reduction in the refrigerant flow rate through the evaporator.
A reduction in the temperature of the cooled substance.
Frost build-up on the evaporator increases airflow resistance and, consequently, causes the fan motor to work harder.

10

Stredne ťažká

What happens when the evaporation temperature drops?


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

11

Stredne ťažká

When is defrosting using the refrigerant possible?


Only when using speed-controlled fans.
In the case of air-cooled chillers, only when the air temperature is above 0°C.
Never. We use electricity for defrosting (for example, using a special electric heater).
Defrosting using the refrigerant is not possible at all.

12

Stredne ťažká

When can frost form on the evaporator surface?


Frost forms only when the refrigeration system is operating continuously.
In the case of finned evaporators.
Frost always forms on air coolers.
Only in the case of air coolers, when the air temperature drops below 0°C.

13

Stredne ťažká

In the case of extensive pipework systems, secondary evaporation of the refrigerant can be prevented by...


additional cooling.
using larger-diameter pipes.
using smaller-diameter pipes.
by insulating the pipes between the compressor and the condenser.

14

Stredne ťažká

How does hot gas defrosting of the evaporator work?


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

15

Stredne ťažká

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


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

16

Stredne ťažká

What conditions must be met for the evaporator to be defrosted using electric heaters?


The electric heaters must be positioned beneath the evaporator’s heat exchange surface.
The electric heaters must be positioned in direct contact with the refrigerant so that the refrigerant flowing through the evaporator is at a sufficiently high temperature.
The electric heaters must be in contact with the evaporator’s heat exchange surface (the heater must touch the fins).
Thanks to the forced air flow created by the fans, the heat from the heaters is transferred to the heat exchanger.

17

Stredne ťažká

Refrigerant distributor:


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

18

Stredne ťažká

What are the possible methods of defrosting air coolers?


Electric defrosting only.
Electric defrosting, liquid defrosting or defrosting using hot refrigerant vapour.
Natural defrosting; there are no other effective methods.
Hot gas defrosting.

19

Stredne ťažká

The boiling point increases (and consequently the rate of evaporation increases) if the pressure above the liquid...


Falls.
Remains constant.
It behaves differently depending on the ambient temperature.
Rises.

20

Stredne ťažká

MOP in thermostatic expansion valves stands for:


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

21

Stredne ťažká

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


regulating the superheat of the refrigerant leaving the evaporator so that it is at the minimum value.
to consistently adjust the evaporation pressure in the condenser depending on the temperature of the refrigerant vapour leaving the condenser.
to maintain a constant suction pressure to the compressor.
to control the amount of refrigerant supplied to the evaporator depending on the superheat of the vapour leaving that heat exchanger.

22

Stredne ťažká

When using a capillary tube, what type of motor can be used in the compressor?


A low-speed motor should be used.
A motor with high starting torque must be used.
A motor with low starting torque can be used.
An electronically commutated motor approved for use with the compressor should be used.

23

Stredne ťažká

What does the thermostatic expansion valve regulate?


The mass flow of the refrigerant injected into the evaporator.
Evaporation pressure after.
Cooling.
Discharge temperature.

24

Stredne ťažká

The refrigerant absorbs heat when...


freezes.
it evaporates.
it condenses.
sublimates

25

Stredne ťažká

In the case of a thermostatic expansion valve, the manufacturer specifies...


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

26

Stredne ťažká

How do we charge a new or repaired system with refrigerant when it is fitted with an expansion valve


behind the condenser to the liquid refrigerant receiver.
to the suction side of the compressor.
in any way.
Charging with refrigerant takes place during operation via the outlet connection of the refrigerant capillary tube.

27

Stredne ťažká

What does a thermostatic/electronic expansion valve regulate?


The amount of refrigerant by controlling the evaporator superheat.
Condenser subcooling by adjusting the condensing pressure.
The evaporation pressure, closing when it falls below the setpoint temperature.
The number of revolutions of the compressor per unit of time.

28

Stredne ťažká

What does the MOP function in expansion valves mean?


This means that these expansion valves are set to a specific suction pressure.
It means that these expansion valves are set to limit the maximum operating pressure.
This means that these expansion valves are set to prevent overheating.
This means that these expansion valves are set to limit subcooling.

29

Stredne ťažká

The lower the temperature of the liquid refrigerant upstream of the expansion valve,


  ...the lower the theoretical coefficient of cooling efficiency qo will be, whilst the cooling capacity Qo remains unchanged.
... the higher the theoretical coefficient of cooling capacity qo will be, and the greater the cooling capacity Qo will be.
...the lower the theoretical coefficient of refrigeration efficiency qo will be, and the lower the refrigeration capacity Qo will be.
...the lower the theoretical coefficient of cooling efficiency qo will be, and the lower the system’s energy efficiency will be.

30

Stredne ťažká

The MOP point in the expansion valve, due to the maximum evaporation temperature of the refrigeration system, ...


The value of the MOP point is irrelevant.
...must be approximately 7 K lower.
...must be approximately 5 K lower.
...must be approximately 7 K higher.

31

Stredne ťažká

What is the function of the suction pressure regulator?


It maintains the suction pressure at a constant level.
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 prevents a drop in suction pressure and, if necessary, shuts down the refrigeration system.

32

Stredne ťažká

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


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

33

Stredne ťažká

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


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

34

Stredne ťažká

What properties should good insulation materials have?


It must have a low thermal conductivity.
It must have a high thermal conductivity.
It must have a good antistatic coating
It must be able to absorb large amounts of moisture.

35

Stredne ťažká

When do we encounter the superheated state?


This is a state that arises as a result of the temperature difference between the suction side and the discharge side of a compressor.
This is the temperature difference between the actual vapour temperature and the vapour temperature at saturation.
It is the temperature difference between the evaporation temperature and the ambient temperature.
It is a condition in which the compressor motor temperature rises excessively.

36

Stredne ťažká

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


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

37

Stredne ťažká

The liquid lines are located...


between the evaporator and the compressor.
between the compressor and the condenser.
between the condenser and the liquid receiver.
between the evaporator and the regenerative heat exchanger.

38

Stredne ťažká

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


The tank is used to collect the liquid refrigerant and excess oil in the system.
The reservoir is used to further cool the liquefied refrigerant leaving the condenser.
The tank is used to store and ensure an adequate supply of refrigerant in the event of fluctuations in the thermal load of the refrigeration system.
When an installation technician does not know the exact amount of refrigerant required, the tank serves as a safety reserve for the entire refrigeration system.

39

Stredne ťažká

What is the purpose of the liquid refrigerant reservoir?


The tank is used to collect the liquid refrigerant and excess oil in the system.
The tank is used to further cool the liquefied refrigerant leaving the condenser.
The tank is required during maintenance work, when there is a temporary need to store the refrigerant that has been circulating in the refrigeration system up to that point.
When an installation technician does not know the exact amount of refrigerant required, the tank serves as a safety reserve for the entire refrigeration system.

40

Stredne ťažká

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.

41

Stredne ťažká

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


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

42

Stredne ťažká

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


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

43

Stredne ťažká

Which refrigerants belong to the HFC group?


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

44

Stredne ťažká

Which refrigerants belong to the HFO group?


R134a, R404A.
R134a, R290.
R22, R12.
R1234yf, R1234ze.

45

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.

46

Stredne ťažká

What does the TEWI parameter define?


It is the global warming potential, expressed in terms of carbon dioxide (CO₂), over a 100-year time horizon.
This is a parameter that quantifies the impact of refrigerants on the ozone layer.
It is the total (global) greenhouse gas equivalent – this indicator takes into account the refrigerant’s direct capacity to contribute to the greenhouse effect and its indirect impact on it through the energy consumption (during the production of which CO₂ is generated) by the refrigeration unit in operation.
This is a parameter defining the ozone layer’s ability to recover (regenerate).

47

Stredne ťažká

What are the characteristics of R452A refrigerant compared to R404A?


It is a flammable and toxic homogeneous refrigerant from the HFC group.
It is a non-flammable refrigerant, a mixture from the HFC/HFO group with thermodynamic properties similar to those of R404A and a GWP approximately 45% lower than that of R404A.
The temperature glide of R452A is half that of R404A.
Both refrigerants are homogeneous refrigerants with no temperature glide.

48

Stredne ťažká

What is the distinguishing feature of R1234yf compared to R134a?


a higher boiling point at standard pressure.
greater flammability.
greater toxicity.
A higher critical temperature.

49

Stredne ťažká

Compared to R134a, the refrigerant CO₂ is characterised by?


Unlike R134a, it is an azeotropic mixture.
It has a temperature slip of 7K greater than R134a.
It has identical thermodynamic properties and can be used as a drop-in replacement for R134a.
It has a lower critical temperature, higher operating pressures and greater volumetric efficiency, allowing for the use of a smaller quantity of refrigerant compared to R134a.

50

Stredne ťažká

The following are not classified as fluorinated greenhouse gases:


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

51

Ťažká

What additional protective equipment will you use when soldering systems containing HC refrigerants?


Tinted safety goggles
Flammable gas detector
High-visibility jacket
Fire blanket

52

Ťažká

Why can’t a sealed high-pressure switch be replaced with a standard mechanical one in a system containing a flammable refrigerant?


There is a risk of refrigerant leakage
Dust and moisture may enter
The pressure switch setting will not be correct
It is a potential source of ignition

53

Ťažká

What is the minimum distance from the work area where HC refrigerants are used at which there must be no sources of ignition?


0.5 m
3 m
1 m
2 m

54

Ťažká

What is the maximum safe charge for a recovery cylinder with R32 refrigerant, if it can be charged with 20 kg of R410A?


18 kg
9 kg
33 kg
20 kg

55

Ťažká

According to EN 378, what is the maximum charge of an A3 refrigerant for a display unit (hermetic, with an internal condenser) located in the ground-floor retail area of a supermarket?


10 kg
1.5 kg
1.0 kg
2.5 kg

56

Ťažká

How can a vacuum pump be used safely to evacuate a system containing a flammable refrigerant?


There is no need to evacuate such systems
Use an ATEX-certified vacuum pump in a well-ventilated area
Fit a long hose to the pump outlet to remove HC away from the system
Position the vacuum pump 3 metres above floor level

57

Stredne ťažká

What is the greenhouse effect?


It alters the composition of the atmospheric air.
It causes an increase in temperature close to the Earth’s surface (up to 10 metres above the surface).
It lowers the average surface temperature of the Earth.
It causes the thermal radiation emitted by the Earth to be trapped in the upper atmosphere.

58

Ťažká

What protective equipment must you have in your car when transporting flammable substances?


Thick gloves
Fire blanket
A fire extinguisher
Tinted safety goggles

59

Ťažká

How would you remove the refrigerant from a 10kg R32 water chiller, located outdoors, before unsoldering the connections?


Recover the R32 until a vacuum is achieved, then charge the system with nitrogen to a relative pressure of 0.1 bar g
Vent the R32 to the outside and drain the system
Recover the R32 until a vacuum is achieved
Vent the R32 to the outside; charge the system with nitrogen until an overpressure is achieved, vent and drain the system twice, charge the system with nitrogen a third time and vent

60

Stredne ťažká

What is R1270?


Isobutane
Butane
Propylen
Propene

61

Ťažká

Which of the following leak detection methods cannot be used to locate an HC refrigerant leak?


Soapy water solution
Leak detection foam
Electronic HFC leak detector
Electronic leak detector for flammable refrigerants

62

Ťažká

What is the most important difference between a flammable refrigerant recovery unit and a standard one?


A flammable refrigerant recovery unit has no ignition sources
Different low-pressure switch setting
Different connection sizes
A different colour for the station

63

Ťažká

Which of the following is a source of ignition?


‘n’ type thermostat
Defrost heating element
Contactor
Ex-certified evaporator fan motor

64

Ťažká

What substance is produced when R32 is burnt?


Carbon monoxide
Hydrochloric acid
Phosgene
Hydrogen fluoride

65

Ťažká

What type of refrigerant is R1234ze?


Hydrocarbon
Hydrofluoroolefin
Chloro-fluoro-hydrocarbon
Hydrochlorofluoro-hydrocarbon

66

Ťažká

What hazards does a Group A3 refrigerant pose?


Low toxicity, moderate flammability
High toxicity, high flammability
High toxicity, moderate flammability
Low toxicity, highly flammable

67

Ťažká

According to EN 378, what is the maximum charge of R290 in a cold store measuring 5 m x 3 m x 2.5 m in height (the LFL for R290 is 0.038 kg/m³)?


0.285 kg
4.93 kg
1.5 kg
1.0 kg

68

Ľahká

What does the GWP indicator mean?


This is an indicator expressing the potential to deplete the ozone layer.
It is a unit expressing the ability to enhance the ozone layer.
It is the global warming potential. The impact on global warming caused by 1 kg of a given gas or chemical substance, expressed as a GWP value, where GWP=1 represents the global warming caused by 1 kg of CO₂ over a period of 100 years (the global warming potential of a unit mass of a given gas over a 100-year period, relative to the warming caused by a unit mass of CO₂).
It is an expansion of the abbreviation ‘Global Warming Potential’ and indicates the rate of increase in air temperature

69

Ťažká

What is the cooling capacity of R32 compared to R410A?


105%
75%
130%
60%

70

Ťažká

Why are Ex-certified evaporator fan motors used in some systems with flammable refrigerants?


Because they are more energy-efficient
Because they must be kept running continuously to disperse the leaking refrigerant
To avoid a source of ignition in the event of a flammable refrigerant leak
Because they are more reliable

71

Ťažká

Why is the difference in density between HC and HFC refrigerants important?


Because it increases operating pressures
Because it affects energy efficiency
Because it affects the charging rate
Because it affects the charge weight

72

Ťažká

What is the GWP value for R290?


675
3
A. 0.02
7

73

Ťažká

Which of the following is not a source of ignition?


Light switch
An Ex-certified fan motor
Open mechanical pressure switch
Electrical switch

74

Ťažká

What is R290?


Ethane
Butane
Propene
Propylene

75

Ťažká

According to EN 378, what is the maximum HC refrigerant charge for a display unit (hermetic system with an internal condenser) located in the ground-floor shopping area of a supermarket?


1.5 kg
1.0 kg
2.5 kg
150 g

76

Ťažká

Why can’t a standard relay be fitted when retrofitting a compressor’s electrical system for flammable refrigerants?


It could be a source of ignition
A relay is never required for compressors using flammable refrigerants
Current consumption differs for compressors using flammable refrigerants compared to those using HFCs
The method of starting the compressor motor differs from that used with HFCs

77

Ťažká

What is the minimum distance from the work area where HC refrigerants are used at which there must be no sources of ignition?


1 m
3 m
10 m
5 m

78

Ťažká

What is the safe charge for a recovery cylinder with R290 refrigerant, if it can be charged with 10 kg of R404A?


3.6 kg
8 kg
17 kg
20 kg

79

Stredne ťažká

How do refrigeration systems contribute to the greenhouse effect, i.e. the rise in atmospheric temperature at the Earth’s surface?


As a result of oil being emitted into the atmosphere by the condenser and filter
Indirectly (through energy consumption) and directly (through the emission of refrigerants into the atmosphere)
Refrigeration equipment emits CO₂ both directly and indirectly.
Through the leakage of refrigerant into the environment.

80

Ťažká

How can a vacuum pump be used safely to evacuate a system containing R290?


There is no need to evacuate systems containing R290
Fit a long hose to the pump outlet to remove HC away from the system
Position the vacuum pump 3 metres above floor level
Use an ATEX-certified vacuum pump in a well-ventilated area

81

Ťažká

In accordance with ADR regulations, what protective equipment must you have in your vehicle when transporting flammable refrigerants?


Fire blanket
A fire extinguisher
Thick gloves
Tinted safety goggles

82

Ťažká

How do you ensure it is safe to light the torch needed to desolder joints in a system that has been evacuated of flammable refrigerant?


Purge the system with oxygen-free nitrogen
Ensure the area is well ventilated and use a flammable gas detector to check the area
Work outdoors
You must not desolder joints on a system containing a flammable refrigerant; they must be cut using a pipe cutter

83

Ťažká

How would you remove the refrigerant from a system containing 100 g of R1270 so that it is ready for the joints to be desoldered?


Vent the R1270 to the outside and drain the system
Recover the R1270 until a vacuum is achieved
Vent the R1270 to the outside; charge the system with nitrogen until an overpressure is reached, vent and evacuate the system twice, charge the system with nitrogen a third time and vent
Recover the R1270 until a vacuum is achieved, then charge the system with nitrogen to a relative pressure of 0.1 bar g

84

Ťažká

Which of the following leak detection methods cannot be used to locate a leak of R290 refrigerant?


Electronic leak detector for flammable refrigerants
Fluorescent dye and a UV lamp
Electronic HFC leak detector
Leak detection foam

85

Ťažká

Why can’t recovery stations designed for HFCs be used with R600a?


The recovery unit cannot withstand the working pressure of R600a
The oil in the recovery unit is not soluble in R600a
It contains ignition sources
The low-pressure switch setting will not be suitable for R600a due to its lower operating pressure

86

Ťažká

According to EN 378, what is the maximum charge of R1234ze in a cold store measuring 5 m x 3 m x 2.5 m in height (the LFL for R1234ze is 0.303 kg/m³)?


227 kg
618 kg
2.27 kg
6.18 kg

87

Ťažká

What type of refrigerant is R32?


Carbon dioxide
Hydrofluorocarbon
Hydrocarbon
Hydrofluoroolefin

88

Ťažká

What hazards do A2L refrigerants pose?


Low toxicity, moderate flammability
High toxicity, high flammability
Low toxicity, high flammability
High toxicity, moderate flammability

89

Ťažká

What danger is associated with the combustion of HFO or HFC refrigerants?


Hydrogen fluoride is produced
Phosgene is produced
Citric acid is produced
Nitrous oxide is produced

90

Stredne ťažká

What is the greenhouse effect, also known as the greenhouse phenomenon?


The absorption of radiation reaching the Earth’s surface.
The filtering out of solar radiation.
It is the phenomenon of heat being trapped in the Earth’s atmosphere (making it difficult for heat to radiate out of the Earth’s atmosphere).
This is the formation of a layer that traps only the heat generated by the combustion of fuel in aeroplanes.

91

Ťažká

What is the approximate displacement volume required for a compressor running on R600a compared to one running on R134a to achieve the same cooling capacity?


Seven times
The same
Twice
Half

92

Ťažká

What is the GWP value for R32?


7
0
675
3

93

Ťažká

Why is the accuracy of the charge weight more important for systems critically charged with R290 compared to those using HFCs


The charge mass is significantly lower than in an HFC system, as the density is much lower
Due to lower operating pressures
Because these systems never have liquid receivers
Because R290 is only used in systems with a charge of less than 150g

94

Ťažká

Why does the condenser fan run continuously in some systems using R1270?


To prevent the build-up of contaminants in the condenser
To reduce energy consumption
To dilute the refrigerant in the event of a leak
To ensure that the discharge pressure never becomes excessive

95

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) 2024/573
Regulation (EU) 2015/1188

96

Stredne ťažká

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


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

97

Stredne ťažká

What are the obligations of manufacturers of refrigeration appliances in the context of ecodesign, and which regulation governs them?


Manufacturers are only required to declare the quantity of F-gas used, in accordance with Regulation (EU) No 517/2014
Manufacturers must comply solely with ISO 9001 standards, without any link to EU regulations
The manufacturer must ensure minimum energy efficiency, reparability and recyclability of equipment, as regulated by Regulation (EU) 2019/2019
Manufacturers are only required to use energy labels, and this is regulated by Regulation (EU) 2024/573

98

Stredne ťažká

What is the main objective of the Ecodesign Directive?


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

99

Stredne ťažká

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


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

100

Ľahká

What is the main function of a relief valve?


Relieves pressure in the system in the event of excessive pressure
It controls the oil level in the compressor
It monitors the moisture content of the refrigerant
Prevents the evaporator from freezing

101

Stredne ťažká

How do certain substances or gases contribute to the greenhouse effect?


When released into the atmosphere, certain substances cause the air to heat up as a result of reactions with the oxygen and nitrogen contained in the air.
Certain substances trap the thermal radiation that the Earth should radiate into the atmosphere. In this way, the Earth gradually warms up and the greenhouse effect occurs.
Some substances damage the ozone layer
Certain substances limit the impact of the Sun’s ultraviolet radiation on the Earth’s surface.

102

Stredne ťažká

What is the purpose of the sight glass in a refrigeration system?


To measure the condenser temperature
To shut off the flow in the event of an emergency
To regulate compressor pressure
For visual assessment of the presence of refrigerant and oil, and for monitoring moisture levels

103

Stredne ťažká

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


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

104

Ťažká

What is the role of the liquid separator in systems using flammable or toxic refrigerants?


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

105

Ťažká

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


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

106

Stredne ťažká

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


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

107

Stredne ťažká

What is the function of the refrigerant receiver in the system?


It maintains a constant pressure in the system
Stores excess refrigerant and facilitates the detection of leaks
It controls the evaporator temperature
Regulates the oil flow

108

Stredne ťažká

What is the role of the manifold thermometer in the refrigeration system?


It monitors the moisture content of the refrigerant
Measures the refrigerant temperature at the compressor inlet and outlet, which helps to identify leaks
Controls the oil level
Relieves pressure in the system in the event of excessive pressure

109

Stredne ťažká

What is the role of the defrost control valves?


They control the pressure in the compressor
They drain off excess oil
Protect the evaporator from excessive icing and reduce the risk of leaks
They are used to monitor the moisture content of the refrigerant

110

Ťažká

Why do CO₂ refrigeration systems require special attention when separating liquid and oil?


CO₂ does not require lubrication, so separators are unnecessary
CO₂ is flammable, so separators cannot be used
CO₂ operates at high pressure, which increases the risk of compressor failure and leaks
CO₂ cannot be used in systems with sight glasses

111

Ťažká

What is the critical pressure of CO₂ (R744)?


Approximately 10 bar
Approximately 31 bar
Approximately 120 bar
Approximately 74 bar

112

Ľahká

What is the base unit of pressure according to the International System of Units (SI)?


Psi
Pa
bar
Atm.

113

Stredne ťažká

Where can I find lists detailing fluorinated greenhouse gases (F-gases)?


In Regulation (EU) No 2024/573 of the European Parliament and of the Council
In the Act on Ozone-Depleting Substances and Certain Fluorinated Greenhouse Gases.
In the Vienna Convention for the Protection of the Ozone Layer.
In the Regulation of the Minister for the Economy on the introduction of a list of fluorinated greenhouse gases.

114

Ťažká

What characterises the transcritical process in CO₂ systems?


It occurs only at low temperatures
It is irrelevant to the operation of the system
Conventional condensation occurs
The system operates above the critical point and the refrigerant does not condense in the conventional manner

115

Ťažká

What characterises the subcritical CO₂ process?


The absence of evaporation
The absence of condensation
The conventional condensation process below the critical point
Operation above the critical point

116

Ťažká

What is the log(p)-h diagram for CO₂ used for?


To measure temperature
To detect leaks
For analysing thermodynamic processes in a refrigeration system
To regulate pressure

117

Ťažká

What can be read from the log(p)-h graph?


Only the humidity
Only the amount of refrigerant
Pressure, enthalpy, temperature and state of the refrigerant
Only the temperature

118

Ťažká

What are CO₂ saturation tables used for?


To determine the relationship between temperature and pressure at saturation
To determine the oil quantity
To measure humidity
To regulate the compressor

119

Ťažká

What does the CO₂ saturation state mean?


A state of high pressure
A state in which the refrigerant is only a gas
Equilibrium between the liquid and vapour phases
Dry ice state

120

Ťažká

When can dry ice (solid CO₂) form?


In the event of a sudden drop in pressure and temperature below the triple point
At high temperature
At high pressure
During normal operation of the system

121

Ťažká

What risks are associated with the formation of dry ice in a CO₂ system?


Blocked pipes and system damage
Improved efficiency
Pressure reduction
No risk

122

Ťažká

How does the CO₂ pressure change as the temperature rises?


It first decreases, then increases
It decreases
It remains the same
Rises sharply

123

Ťažká

Why is understanding the log(p)-h graph particularly important for CO₂?


It is only used for design purposes
It only applies to NH₃
It doesn’t matter
As CO₂ systems operate in different modes (sub- and transcritical) and require detailed analysis

124

Stredne ťažká

Where can I find the lists specifying controlled substances?


In Regulation (EU) No 2024/590 of the European Parliament and of the Council.
In the Vienna Convention for the Protection of the Ozone Layer.
In the Regulation of the Minister for the Environment on the list of controlled substances.
In the current Act on Ozone-Depleting Substances and Certain Fluorinated Greenhouse Gases.

125

Ťažká

What happens to CO₂ above the critical point?


It ceases to conduct heat
It turns into a solid
It turns into a liquid
It transitions to a supercritical state (no distinction between liquid and gas)

126

Ťažká

Why do CO₂ systems require precise pressure control?


Due to significant pressure changes with temperature fluctuations
Due to low pressures
Because there are no valves
They do not require control

127

Stredne ťažká

Why is ammonia (NH₃) considered a toxic refrigerant?


It is highly irritating to the respiratory tract and toxic if inhaled
It is colourless and odourless, so it is difficult to detect
It is flammable and can form explosive mixtures with air
It does not react with water, which makes it difficult to neutralise

128

Ťažká

What is the main difference between a dry evaporator and a flooded evaporator?


A dry evaporator is filled with refrigerant liquid, whilst a flooded evaporator is filled with gas
A dry evaporator has a lower operating pressure than a flooded one
A dry evaporator allows the entire refrigerant to evaporate in the pipe upstream of the compressor; in a flooded evaporator, part of the refrigerant remains in a liquid state within the evaporator
A dry evaporator does not require an expansion valve, whereas a flooded one does

129

Ťažká

What is the typical pressure in deep-freezing systems (below −40 °C) for an evaporator in a system using R717?


A pressure varying between 10 and 20 bar
Negative pressure (vacuum), below 0 bar
Positive pressure, in the range of 5–10 bar
Atmospheric pressure, approximately 1 bar

130

Ťažká

Why are PFAS substances formed as a result of the decomposition of certain F-gases problematic?


They are readily biodegradable, so they only pollute the environment for a short time
They are persistent, accumulate in the environment and may be toxic
They are climate-neutral
They cause rapid cooling of the atmosphere

131

Ťažká

What is the basic requirement when charging a system with R717 (NH₃)?


NH₃ can be charged together with air
Charging should take place in a well-ventilated area using appropriate personal protective equipment
Charging can be carried out without personal protective equipment
Charging must only take place at temperatures below 0°C

132

Ťažká

How should oil be handled in systems using R717?


Oil can be mixed with any refrigerant
The oil does not require any monitoring
The oil should be checked regularly and any excess removed from the lower parts of the units to prevent reduced heat transfer and leaks
Oil has no effect on the system’s operation

133

Ťažká

What is the correct procedure for recovering R717 from a system?


Recovery is not required
The gas can be released into the atmosphere
The refrigerant must be recovered into suitable, leak-proof tanks designed for NH₃
The refrigerant can be drained into the sewer system

134

Ťažká

How should R717 (NH₃) be stored?


Near heat sources
In any open containers
In unmarked plastic containers
In sealed, labelled containers, in a cool and well-ventilated place

135

Stredne ťažká

Where and by when should annual reports on ODS and F-gases be submitted?


Reports for the previous year must be submitted by 31 January electronically by completing the special forms available in the central register of operators ‘CRO’.
Reports for the previous year must be submitted by 31 March of the relevant year electronically to the Ministry of the Environment.
Reports on ODS and F-gases for the previous year must be submitted by 28 February of the following year, via the IT system available in the reports database at the Office for the Protection of the Ozone Layer and Climate (BOWOiK) on the ICHP website.
Reports must be submitted by the end of the relevant calendar year, using a special form at the regional branch of the Office of Technical Inspection (UDT)

136

Ťažká

What should be done in the event of R717 contamination?


Release into the atmosphere
Continue to use without restriction
The refrigerant must be purified or sent for disposal in accordance with regulations
Add water to dilute it

137

Ťažká

What is the main hazard associated with an R717 leak during maintenance work?


Damage to electrical equipment only
Toxic to humans and may cause chemical burns
Increased cooling efficiency
No risk whatsoever

138

Ťažká

What action should be taken if an NH₃ leak is detected?


Ignore it and carry on working
Increase the pressure in the system
Evacuate personnel immediately and remove the source of the leak, if it is safe to do so
Close your eyes and carry on working

139

Ťažká

What role do scrubbers play in NH₃ systems?


They store the refrigerant
They are used to measure temperature
Neutralises ammonia through absorption in a liquid (e.g. water)
They increase the pressure in the system

140

Ťažká

How should the system be prepared before filling with R717?


Simply start it up
There is no need to check it
The pressure must be increased above the standard level
Check for leaks, remove air and moisture, and create a vacuum

141

Ťažká

What are the transport requirements for R717?


Must be transported in suitable, labelled containers in accordance with ADR regulations
It can be transported in open containers
Transport is not subject to regulations
It can be transported without labelling

142

Ťažká

What personal protective equipment is required when working with NH₃?


No requirements
Workwear only
Safety goggles, gloves and respiratory protective equipment
Only a safety helmet

143

Stredne ťažká

Which measure has the greatest impact on improving the compressor’s energy efficiency during installation?


Installation without filters
Correctly create a vacuum and remove moisture from the system
Increasing the amount of refrigerant
Installation without a leak test

144

Stredne ťažká

How does regular monitoring of the oil level affect the compressor’s operation?


It has no effect
Ensures proper lubrication and improves energy efficiency
It reduces cooling capacity
Causes a rise in pressure

145

Stredne ťažká

How do system leaks affect the compressor’s energy efficiency?


These cause a drop in performance and an increase in energy consumption
They improve efficiency
Have no effect
They lower the operating temperature

146

Stredne ťažká

Regulation (EC) No 2024/590 relates to:


Ozone-depleting substances.
Health and safety at work during the recovery of refrigerants.
The conditions for obtaining F-gas certificates by companies carrying out the recovery and reclamation of waste refrigerants.
Alternative refrigerants serving as substitutes for fluorinated greenhouse gases.

147

Stredne ťažká

What is the significance of regulating suction and discharge pressure?


Helps maintain optimal operating conditions for the compressor
It has no effect on efficiency
Increases oil consumption
Causes leaks

148

Stredne ťažká

What maintenance measure reduces the compressor’s energy consumption?


Disabling safety devices
Lack of servicing
Increasing the refrigerant charge
Regular replacement of filters and dryers

149

Stredne ťažká

How does the presence of air in the refrigeration system affect performance?


Reduces energy consumption
Leads to increased pressure and reduced efficiency
It has no effect
It improves efficiency

150

Stredne ťažká

What role do control systems (e.g. regulators) play in compressor efficiency?


It increases the amount of refrigerant
Enables optimisation of operation and a reduction in energy consumption
Causes leaks
It doesn’t matter

151

Stredne ťažká

How does refrigerant superheat at the compressor suction affect performance?


It has no effect
It always improves performance
It only causes a drop in temperature
Excessive overheating reduces efficiency and increases energy consumption

152

Stredne ťažká

How does the correct layout of the system affect efficiency?


Shortens flow paths and reduces energy losses
It causes the temperature to rise
It doesn’t matter
It increases the pressure

153

Stredne ťažká

How important is pipe insulation?


Reduces heat loss and improves energy efficiency
Causes a rise in pressure
It increases energy consumption
It has no effect

154

Stredne ťažká

Which measure most improves the condenser’s energy efficiency?


Restricted airflow
Contamination of the heat exchange surface
Regular cleaning of heat exchange surfaces
Increasing the amount of refrigerant

155

Stredne ťažká

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


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

156

Stredne ťažká

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


It doesn’t matter
Insufficient airflow reduces efficiency
Causes a drop in pressure
Ensures effective heat dissipation and improves energy efficiency

157

Stredne ťažká

Which refrigerants cause damage to the ozone layer?


All refrigerants that contain carbon in their molecular structure.
All refrigerants that contain fluorine and hydrogen in their molecules.
All refrigerants that are hydrocarbon derivatives.
All refrigerants that contain chlorine or bromine in their molecules.

158

Stredne ťažká

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


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

159

Stredne ťažká

How does correct condensation pressure control affect efficiency?


It increases energy consumption
Causes leaks
It has no effect
Maintains optimum operating conditions and reduces energy consumption

160

Stredne ťažká

How do condenser leaks affect energy efficiency?


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

161

Stredne ťažká

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


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

162

Stredne ťažká

How does hot air recirculation affect the condenser?


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

163

Stredne ťažká

How does the insulation of central heating and domestic hot water pipework affect the operation of the heat pump’s condenser?


It impairs cooling
It doesn’t matter
It increases the pressure
Reduces energy losses and improves the efficiency of the entire system

164

Stredne ťažká

Which measure most improves the energy efficiency of the evaporator?


Increasing the condensation temperature
Regular defrosting of the evaporator
Restricted airflow
Increasing the amount of refrigerant

165

Stredne ťažká

How does evaporator icing affect the system’s operation?


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

166

Stredne ťažká

How does dirt on the evaporator surface affect its performance?


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

167

Stredne ťažká

What maintenance task is crucial for the evaporator?


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

168

Stredne ťažká

What does an F-gas personal certificate (Category A2) authorise?


To recover refrigerant from equipment containing less than 3 kg of fluorinated greenhouse gases, or less than 6 kg in the case of hermetically sealed systems.
to make permanent joints by brazing in systems containing fluorinated greenhouse gases.
to repair, maintain or service refrigeration equipment and systems containing controlled substances.
for the purchase of lubricants and refrigeration oils, and for the testing of safety valves.

169

Stredne ťažká

How does superheating of the refrigerant at the evaporator outlet affect efficiency?


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

170

Stredne ťažká

How do leaks in the evaporator affect efficiency?


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

171

Stredne ťažká

How important is correct expansion valve adjustment?


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

172

Stredne ťažká

How does inadequate insulation of the heat transfer circuit pipes affect evaporator performance?


Causes cooling losses and increased energy consumption
It has no effect
It lowers the condensation temperature
It improves efficiency

173

Stredne ťažká

How does correct TEV valve adjustment affect the system’s energy efficiency?


It increases energy consumption
Ensures optimum superheat and improves system efficiency
It has no effect
Causes leaks

174

Stredne ťažká

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


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

175

Stredne ťažká

How does a 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

176

Stredne ťažká

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


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

177

Stredne ťažká

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


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

178

Stredne ťažká

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


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

179

Stredne ťažká

What does Regulation (EU) No 2024/573 of the European Parliament and of the Council cover?


The Regulation sets out requirements relating to brazing of refrigeration systems.
The Regulation sets out health and safety requirements for soldering work.
The Regulation concerns leak testing of stationary refrigeration, air-conditioning and heat pump equipment containing fluorinated greenhouse gases. The Regulation sets out the requirements relating to leak testing of such equipment.
The Regulation concerns gases that contribute to the greenhouse effect.

180

Stredne ťažká

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


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

181

Stredne ťažká

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


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

182

Stredne ťažká

What is the main design difference in hydrocarbon-based refrigeration systems?


No need for safety measures
Lower energy efficiency
Higher operating pressures
The need for explosion-proof measures due to the flammability of the refrigerant

183

Stredne ťažká

What differences are there in the compressors used in hydrocarbon systems?


They must be designed to operate with flammable refrigerants (e.g. hermetic compressors)
They must operate at higher pressures
They do not require lubrication
No differences

184

Ťažká

What is the main characteristic of R744 (CO₂) refrigeration systems?


Very high operating pressures
Low operating pressures
No need for regulation
Low energy efficiency

185

Ťažká

What are the requirements for piping materials in CO₂ systems?


It does not matter
They must be made exclusively from plastics
They must be able to withstand high pressures (e.g. high-grade steel)
They may be made of any material

186

Ťažká

How does a booster system work in CO₂ installations?


It reduces the pressure in the evaporator
It utilises two stages of compression (low and medium pressure) in a single system
It is used to store the refrigerant
It reduces the amount of refrigerant

187

Ťažká

What is the function of high-pressure control valves in CO₂ systems?


They control the pressure on the high-pressure side and optimise system operation
They are used to store the refrigerant
They lower the evaporator temperature
They regulate oil flow

188

Ťažká

Why is pressure optimisation in CO₂ systems crucial?


It reduces the amount of refrigerant
It doesn’t matter
It enables the system to achieve maximum energy efficiency
It reduces the ambient temperature

189

Ťažká

What role do parallel-operating compressors play in CO₂ systems?


They lower the ambient temperature
It does not matter
They increase energy consumption
They enable gas recovery from the medium-pressure stage and improve efficiency

190

Stredne ťažká

How can one check whether the system has been overcharged with refrigerant?


Under normal conditions, there is a marked increase in condensing pressure because an excessive amount of refrigerant accumulates in the condenser, reducing the heat exchange surface area within it.
The compressor will operate under a lower load and the suction pressure will decrease
The refrigeration system is overcharged with refrigerant whilst in operation, and even under a very small heat load, frost forms on the suction side of the compressor
This cannot be checked with sufficient reliability, as the sight glass is not designed for this purpose.

191

Ťažká

How does an ejector work in a CO₂ system?


It uses the energy of the higher-pressure refrigerant to raise the pressure of the refrigerant from the lower stage, which improves efficiency
Stores the refrigerant
It lowers the evaporator temperature
It increases the amount of refrigerant

192

Ťažká

What is the function of liquid ejectors in CO₂ systems?


They reduce atmospheric pressure
They raise the refrigerant temperature
They assist with liquid recovery and improve evaporator feed
They increase the amount of oil

193

Ťažká

What are the characteristics of partially flooded systems in CO₂ systems?


Low operating pressure
The absence of liquid in the evaporator
The presence of liquid in the evaporator, which improves heat transfer and efficiency
Lack of regulation

194

Ťažká

What is the main risk associated with static pressure in CO₂ systems?


A decrease in refrigerant quantity
A rise in pressure resulting from the refrigerant heating up whilst at rest
A drop in temperature
Increased efficiency

195

Ťažká

How can standstill pressure in CO₂ systems be reduced?


By shutting down the system completely
By increasing the temperature
By using parallel compressors and external cooling systems
By increasing the refrigerant charge

196

Ťažká

What does ‘stagnation’ of a refrigeration system mean in the context of CO₂?


Improved efficiency
A lack of refrigerant flow, which can lead to increased pressure and safety risks
Normal system operation
A drop in temperature

197

Ťažká

Why do CO₂ systems require more advanced automation than traditional systems?


They do not require automation
Due to low pressures
Due to the need for precise control of pressure and temperature
Because there are no valves

198

Ťažká

What must be included on the label of a cylinder containing a flammable refrigerant?


Information about the cylinder owner
Net weight only
The name of the refrigerant, the hazard symbol and basic safety information
Agent name only

199

Ťažká

Why does the absence of a ‘flammable agent’ label on the system pose a significant hazard?


It has no significant impact on safety
It may lead to the incorrect selection of oil
It may lead to the use of tools that are a source of ignition
It reduces the system’s efficiency

200

Ťažká

Which set of information on the label of a flammable agent cylinder is crucial from a safety perspective?


Gross weight and batch number
Cylinder colour and date of manufacture
Name of the substance, hazard pictogram, UN number
Manufacturer’s name and country of origin

201

Stredne ťažká

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


carry out a start-up test.
carry out a leak test.
complete the unit’s data sheet.
check the compressor’s suction and discharge connections.

202

Ťažká

What is the requirement regarding the labelling of an installation containing a flammable substance?


Labelling is not required for hermetically sealed systems
The labelling must indicate the type of substance and the flammability hazard
Labelling is required only in technical rooms
Colour-coding of pipes is sufficient

203

Ťažká

What are the potential consequences of using unsuitable connections in a system containing a flammable substance?


Merely a reduction in efficiency
Risk of leakage and the formation of an explosive mixture
Merely installation difficulties
No impact on safety

204

Ťažká

What is the purpose of installing gas detectors in a room with a refrigeration system?


Regulating compressor capacity
Measuring the refrigerant temperature
Monitoring pipe pressure
Early detection of refrigerant leaks and prevention of health risks

205

Ťažká

How often should gas detection sensors in the service room be checked?


Once every 5 years
Before each start-up of the unit
In accordance with the manufacturer’s instructions and applicable health and safety regulations
Only after a leak has occurred

206

Ťažká

Where should a gas detector be positioned in accordance with EN 378?


Only at the entrance to the room
On the ceiling if the gas is lighter or heavier than air; near the floor if it is lighter or heavier
Near the control panel
Anywhere in the room

207

Ťažká

How should an employee respond when a gas alarm is triggered?


Leave the room immediately and notify their supervisor
Reduce the pressure in the system
Switch off the system and wait for the alarm to stop
Carry on working until they see a leak

208

Ťažká

What safety checks should be carried out when installing a new refrigeration system?


Only the compressor power
The presence of health and safety signage, adequate ventilation and gas detectors
Is the air filter new?
The colour of pipes and hoses

209

Ťažká

Gas detectors should be installed in rooms where:


Any refrigerant is present, regardless of the quantity
The room is less than 5 m²
The amount of refrigerant exceeds a specified permissible threshold
Ventilation is natural

210

Ťažká

What is the minimum number of emergency exits in a plant room (refrigeration plant room) and how should they be signposted?


At least two exits, but signage is optional
One exit, clearly marked in the direction of escape
Exits do not need to be signposted if the room is small
One exit with an information sign about the refrigerant

211

Ťažká

Which measure, when installing a system using a flammable refrigerant, improves its energy efficiency?


Thorough leak testing and vacuuming
No leak test
Increasing the refrigerant charge
Restriction of ventilation

212

Stredne ťažká

What information must appear on the unit’s label?


Markings regarding the weight and capacity of the pipework, together with the colour code and chemical composition of the paints used to coat the frame and casing.
Among other things: information stating that the unit contains a fluorinated greenhouse gas, together with the industrial designation of the gas or its chemical name, the mass of the gas and its CO₂ equivalent
The manufacturer’s logo and the weight of the unit.
It does not matter what should be included on the device label.

213

Ťažká

How do leaks affect systems using flammable refrigerants?


Have no effect
They improve efficiency
They cause refrigerant loss, reduced efficiency and a fire hazard
They lower the temperature

214

Ťažká

Why is it important to limit the amount of refrigerant in HC systems?


It reduces the risk of explosion and improves the system’s operational safety
It has no effect
It increases efficiency
It lowers the temperature

215

Ťažká

Why is the cleanliness of heat exchangers in HC systems important?


It increases the pressure
It doesn’t matter
It improves heat transfer and reduces energy consumption
Causes leaks

216

Ťažká

What maintenance measures improve the efficiency of a system using a flammable refrigerant?


Disabling safety devices
Increasing the refrigerant charge
Lack of servicing
Regular checks for leaks and operating parameters

217

Ťažká

How does the correct selection of components affect a system using a flammable refrigerant?


It increases the amount of refrigerant
It doesn’t matter
It ensures safe and optimal operation and minimises energy losses
It lowers the temperature

218

Ťažká

Why is it important to use the correct service tools in HC systems?


It increases energy consumption
Causes leaks
It ensures operational safety and reduces refrigerant losses
It doesn’t matter

219

Ťažká

How does pipe insulation affect the efficiency of systems containing HC?


It reduces energy losses and improves efficiency
It doesn’t matter
Causes leaks
It increases the pressure

220

Ťažká

Which safety class applies to R744?


A1
B2L
A2
A3

221

Ťažká

In an R744 system operating in supercritical mode, the refrigerant entering the evaporator expansion valve is...


A supercritical fluid
A two-phase mixture at intermediate pressure
Saturated vapour at intermediate pressure
A subcooled liquid

222

Ťažká

In R744 supercritical systems, the gas cooler outlet valve controls:


The gas cooler fans
The pressure in the gas cooler
The outlet temperature of the gas cooler
The inlet temperature to the gas cooler

223

Stredne ťažká

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


°F
K
°R
°C

224

Stredne ťažká

Which of the following are the most important pieces of information that should be included in the unit’s data sheet:


The owner, installer and service technician of the unit.
Operator details, unit details, type and quantity of refrigerant, information regarding servicing and repairs.
Information regarding refrigerant recovery and unit dismantling.
The make and model of the unit, so that the manufacturer can be contacted to obtain the technical information necessary for servicing.

225

Ťažká

Which statement best describes the behaviour of R717 and mineral compressor oil?


R717 does not mix with compressor oil, so the oil remains in the system on the low-pressure side as a layer beneath the R717
In an R717 system, a return oil line cannot be used because the oil is too hot
R717 does not mix with compressor oil, so the oil remains in the system on the high-pressure side as a layer above the R717
R717 mixes very well with compressor oil and easily returns to the compressor

226

Ťažká

What is the main reason for using K65 copper tubing in some R744 systems?


They bend easily
They can withstand higher pressures
They have good low-temperature performance
They come in a wider range of diameters

227

Ťažká

Which of the following statements is correct regarding the installation of Schrader valves?


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

228

Ťažká

Which refrigerant can be detected using phenolphthalein paper?


R744
R1234ze
R717
R1270

229

Ťažká

How does a refrigerant shortage affect the high-pressure side of the system (without discharge pressure regulation)?


The discharge pressure will be lower, and the subcooling will be lower
Discharge pressure will be lower, subcooling will be higher
Discharge pressure will be higher, and the degree of subcooling will be lower
Discharge pressure will be higher, and the degree of subcooling will be higher

230

Ťažká

What is the benefit of using helium as a tracer gas in nitrogen during a pressure test?


It is non-flammable
It has a distinct odour
It has a higher pressure than pure nitrogen
It has smaller molecules and diffuses more easily

231

Ťažká

Why should an R744 system that has been drained be initially charged with the refrigerant in gaseous form?


To prevent damage to the compressor
To prevent the drain valve from opening
To prevent the formation of dry ice
To ensure that R744 is charged slowly

232

Ťažká

If an R744 system contains moisture because it has not been properly drained, what is the likely consequence?


Excessively high discharge pressure
The formation of hydrogen fluoride, which will decompose into hydrofluoric acid and damage the compressor
The formation of carbonic acid, which will cause damage to the system
Reduced cooling capacity

233

Ťažká

Which system may require manual oil recovery?


An R717 system
R744 cascade system
Supercritical ‘booster’ system using R744
Secondary system using R744

234

Ťažká

The pressure of R744 at a saturation temperature of 20 °C is approx.


56 bar g
14 bar g
90 bar g
25 bar g

235

Stredne ťažká

Who is responsible for drawing up the equipment or installation record?


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

236

Ťažká

Which refrigerant is lighter than air?


R1270
R717
R744
R1234ze

237

Ťažká

What hazards are associated with a Class A3 safety agent?


High flammability, lower toxicity
Slightly flammable, lower toxicity
High toxicity, does not propagate flames
Lower toxicity, does not propagate flames

238

Ťažká

18 What is the GWP of R32 (according to AR4)?


0
3945
675
6

239

Ťažká

What factors are taken into account when determining the maximum charge for comfort air-conditioning/heating applications?


Lower flammability limit, room volume
Practical limit, height of the indoor unit, floor area
Practical limit, room volume
Lower flammability limit, height of the indoor unit, floor area

240

Ťažká

What compressor displacement is required for R1270, relative to R404A compressors for the medium-temperature range (cold store)?


Similar
150%
50%
600%

241

Ťažká

At an ambient temperature of 25°C, the standby pressure in the low-pressure stage of an R744 cascade system will typically be…


27.5 bar g
Higher than the maximum permissible pressure in the low-pressure stage
The same as the high-pressure setting on the pressure switch
The same as the pressure set on the relief valve

242

Ťažká

What is the correct definition of critical temperature?


The temperature at which the vapour pressure of a liquid is equal to the ambient pressure surrounding the liquid
The temperature at which a substance changes from a gaseous to a solid state
The temperature above which there are no distinct liquid and gaseous phases
The temperature at which, for certain substances, electrical resistance is zero

243

Ťažká

In a supercritical system, under supercritical conditions, the working fluid in the gas cooler


it loses heat when its pressure drops
it loses heat as its temperature drops
loses heat at constant temperature and pressure
loses heat during a phase change

244

Ťažká

R717 is highly corrosive to


copper
aluminium
titanium
stainless steel

245

Ťažká

What is the effect of repeatedly opening the relief valve?


The valve will not open
The relief pressure drops
The relief pressure rises
The valve remains fully open continuously

246

Stredne ťažká

Oil traps on the suction pipework are required:


before the safety valve.
always before any rise in the pipeline.
before the compressor.
at the inlet to each component of the refrigeration system.

247

Ťažká

What is the relationship between the pressure (P) and temperature (T) of nitrogen at the start (1) and end (2) of the leak test?


P2 = T2/(P1 × T1)
P2 = (P1 × T2)/T1
P2 = (P1 × T1)/T2
P2 = T1/(P1 × T2)

248

Ťažká

What is the recommended alarm level for fixed leak detection systems for R717?


500 ppm
5,000 ppm
50,000 ppm
500,000 ppm

249

Ťažká

Why are compressors with a separate electric motor most commonly used in R717 (NH₃) refrigeration systems?


To increase the amount of refrigerant in the system
To reduce the condensing pressure
Because NH₃ reacts with the motor windings and hermetic compressors are not used
Because compressors with a separate motor are cheaper

250

Ťažká

Which type of compressor is most commonly used in large ammonia systems?


Diaphragm compressor
Rotary vane compressor
A reciprocating or screw compressor
Hermetic scroll

251

Ťažká

How is the capacity of a piston compressor regulated in NH₃ systems?


By unloading the cylinders or changing the rotational speed
By increasing the condensing pressure
Solely by adjusting the oil volume
By reducing the refrigerant charge

252

Ťažká

How is the capacity of a screw compressor most commonly controlled?


By adjusting the oil level
By changing the type of oil
By closing the suction valve
By using a slide valve

253

Ťažká

When is two-stage compression used in NH₃ systems?


At very low vapour pressures and high pressure differentials
Exclusively in small systems
At small temperature differences
Only with water-cooled condensers

254

Ťažká

What is the advantage of two-stage compression over single-stage compression?


No need for a separator
Higher efficiency and lower discharge temperature
Higher energy consumption
Lower efficiency

255

Ťažká

How does an evaporative condenser used in NH₃ systems work?


Operates without a fan
It utilises the evaporation of water to increase cooling efficiency
It does not require a water supply
It transfers heat only to the air

256

Ťažká

What is the function of the liquid separator in an NH₃ system?


It prevents liquid from entering the compressor
Regulates the condensing pressure
Increases the discharge temperature
It separates oil from the refrigerant

257

Stredne ťažká

When is there a refrigerant leak, even though the compressor is still running?


When the suction pressure is low, superheat is high, subcooling is negligible and the temperature difference between the condenser and the expansion valve is small.
When the sight glass is full of liquid refrigerant and we observe a rise in the oil level in the compressor sump.
When the condensing pressure and suction pressure rise, but there is no superheat.
When we observe a rise in the refrigerant level in the liquid receiver and the subcooling increases.

258

Ťažká

What is the purpose of monitoring the liquid level in the separator?


To maintain the correct refrigerant level and prevent the compressor from flooding
To control the condenser fan
To increase the oil volume
To reduce the condensing temperature

259

Ťažká

What is the role of the float switch in NH₃ systems?


It is used to detect leaks
It controls the fan’s operation
It regulates the condensation temperature
It monitors the liquid level in the tank or separator

260

Ťažká

What is a thermosiphon in NH₃ systems?


A type of safety valve
A type of evaporator
An oil circulation system utilising differences in pressure and temperature
A defrosting device

261

Ťažká

Why are oils that are immiscible with the refrigerant used in NH₃ systems?


Because the oil mixes only with water
To reduce the pressure
Because NH₃ does not mix with most compressor oils
To increase the amount of refrigerant

262

Ťažká

What is the main function of an oil separator in NH₃ systems?


To increase fan efficiency
To lower the condensation temperature
To separate the oil from the refrigerant and return the oil to the compressor
Removing moisture from the system

263

Ťažká

Which NH₃ system features direct evaporation of the refrigerant in the evaporator?


Indirect system
Direct expansion (DX) system
Thermosiphon system
Glycol system

264

Ťažká

What is the characteristic feature of a flooded evaporator system?


No separator is used
The evaporator is filled exclusively with vapour
The evaporator contains a large amount of liquid, which improves heat transfer
No level control is required

265

Ťažká

What is the main difference between a direct and an indirect system?


In an indirect system, NH₃ cools an intermediate medium (e.g. glycol), which in turn cools the load
In an indirect system, NH₃ flows directly into the space being cooled
In an indirect system, no compressor is used
In a direct system, there is no evaporator

266

Stredne ťažká

Which components of a refrigeration system can be classified as potential leak points (leaks) subject to regular leak tests?


All parts of the refrigeration unit that are connected to the suction side of the refrigeration system.
Fittings, valves including their stems, seals – including those in replaceable filters and dryers, components exposed to vibration, and connections to measuring, control and safety devices.
Hermetic compressors, liquid refrigerant tanks and liquid separators.
Parts of the system located on the high-pressure side (from the compressor up to and including the expansion valve).

267

Stredne ťažká

What is the test pressure during the pressure leak test of the unit?


The test pressure (maximum) is 30 bar.
The test pressure for leak testing is equivalent to the maximum operating pressure measured during the operation of the refrigeration unit.
The test pressure is determined by the person carrying out the leak test based on their experience.
According to the PN-EN 378 standard, at least 0.25 times the maximum permissible pressure for the system (PS).

268

Stredne ťažká

In which part of the refrigeration unit must the recommended leak test be carried out?


The check must be carried out on all parts of the refrigeration system that are connected to the discharge side of the refrigeration circuit.
The test must be carried out at all points on the refrigeration unit where there is a potential risk of refrigerant leakage.
The check should only be carried out at the connection points for measuring instruments (pressure switches, pressure gauges, temperature sensors).
The test must be carried out on the compressor shut-off valves, solenoid valves and filters.

269

Stredne ťažká

When can a given unit be considered perfectly leak-tight?


The device in question is perfectly leak-tight when we have carried out a check using a permanently installed electronic detector.
A device can be considered perfectly leak-tight if gas bubbles appear when it is submerged in water.
A given unit can be considered perfectly leak-tight if, during a leak test, the pressure remains constant, taking into account pressure changes caused by temperature variations. Any drop in pressure indicates a leak and requires the location of the leak to be identified.
A given device can be considered perfectly leak-tight when the pressure drop during the test does not exceed 0.1 bar.

270

Stredne ťažká

What does EU Regulation 1516/2007 cover?


The Regulation addresses the disposal of gases that contribute to the greenhouse effect.
The Regulation sets out requirements relating to brazing of refrigeration systems.
The Regulation sets out health and safety requirements for soldering work.
The Regulation concerns leak testing of stationary refrigeration, air-conditioning and heat pump equipment containing fluorinated greenhouse gases. The Regulation sets out the requirements for leak testing of such equipment.

271

Ťažká

Which parts of refrigeration systems must be inspected on a mandatory and regular basis in accordance with EU Regulation 1516/2007?


Connections on the condenser, as there is high pressure and the refrigerant is in liquid form
Compressor connections, 2. connections on the liquid refrigerant tank
Fittings, 2. valves, 3. seals, 4. parts/components exposed to vibration, 5. connections at safety devices.
Only compressor connections, as these are subject to vibration.

272

Ľahká

What is superheat?


It is the amount of heat required to turn a liquid into vapour.
It is the amount of heat required to cause the vapour formed from a liquid to become superheated.
It is the amount of heat required to increase the pressure.
It is the amount of heat required to heat a liquid.

273

Ťažká

In accordance with EU Regulation 1516/2007, there are several methods of leak testing. What are these methods called?


We distinguish between methods for quality control of supplied materials and leak testing methods that do not involve quality control of supplied materials.
We distinguish between quality control methods for supplied materials and electronic testing methods.
We distinguish between direct and indirect methods of leak detection.
We distinguish between physical and chemical methods.

274

Ťažká

In accordance with EU Regulation 1516/2007, to whom can we entrust the responsibilities for leak testing of refrigeration systems?


The check may be carried out by a specialist in leak testing.
The check may only be carried out by a person who has previously carried out such a check.
The inspection may be carried out by a person employed and appointed by the owner of the installation.
The test may only be carried out by a competent person with the relevant skills, who holds a certificate attesting to the necessary knowledge in this field. They must also hold a certificate for companies regarding the operation and maintenance of refrigeration equipment charged with F-gases.

275

Ťažká

In accordance with EU Regulation 1516/2007, what conditions must be met in order to carry out a leak test on refrigeration systems using ultraviolet (UV) light?


A prerequisite for carrying out a leak test using UV is having the appropriate technical resources, the relevant materials supplied, and suitable safety goggles.
A prerequisite for carrying out a leak test using UV is that such a test is technically feasible.
A prerequisite for carrying out the inspection is holding the relevant authorisation for pressure testing issued by the UDT.
The manufacturer of the refrigeration equipment must confirm that the aforementioned UV method can be used. A UV leak test may be carried out by a qualified person who holds the relevant qualifications (certificate).

276

Ťažká

In accordance with EU Regulation 1516/2007, which leak testing methods are classified as direct leak testing methods?


Detection of leaks using a handheld leak detector and/or a fixed leak detection system; 2. Detection of leaks using a special dye with UV-fluorescent properties; 3. Detection of leaks using a foaming solution.
Leak test using nitrogen with a tracer gas, an electronic detector and pressure measurement.
Leak testing by measuring pressure changes and the method of submerging the device/system in water.
Leak test following the creation of a vacuum and leak detection using a foaming solution.

277

Ťažká

In accordance with EU Regulation 1516/2007, which methods are classified as indirect leak testing methods?


This method is based on the analysis of the following parameters: pressure, temperature, operating pressure, liquid level, oil leakage, etc.
It utilises pressure and temperature measurements, as well as an ultrasonic method.
Leak detection using a UV tracer.
This method is based on electronic leak detection.

278

Stredne ťažká

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


We increase the pressure at a rate of 10 bar/s.
We increase the pressure gradually whilst checking for leaks, until the test pressure is reached, at a rate of no more than 2 bar/min
We increase the pressure in any way.
We increase the pressure as quickly as possible.

279

Stredne ťažká

What electronic equipment should be used to carry out leak testing?


Only with devices fitted with an infrared detector.
Only with devices fitted with hot cathodes.
Only with devices fitted with an ‘Ion Pump’ sensor.
Only using devices with verified measurement sensitivity.

280

Stredne ťažká

What documentation should be checked before starting a leak test?


The maintenance log and the machine/device operating instructions must be checked.
Check the stock ledger (accounts).
Check the time sheets of the staff responsible for the machinery/equipment.
Check the operating instructions for the machine/equipment.

281

Stredne ťažká

What information must be recorded when drawing up the leak test report?


The method used to carry out the leak test, the number of faults, the method of repairing the faults, the time taken to work on the installation, and the cost of the repair.
The date of the inspection, a record of the occurrence of the leak, and a signature.
The date of the inspection, the number of faults (leaks), the location of the faults (leaks), the proposed method of rectifying the fault/defect (leak), attached documents and a signature.
The number of locations where leaks have occurred and the date of the inspection.

282

Stredne ťažká

What pressure values should be used for the pressure leak test?


Use a pressure not exceeding the maximum permissible pressure for the system (PS).
The pressure for the leak test is 2–3 bar.
At the discretion of the person authorised to carry out the pressure test.
The pressure value for the leak test is 10–12 bar.

283

Stredne ťažká

What is temperature slip?


It involves a decrease in temperature.
A specific temperature cannot be assigned to a given vapour pressure. There is a temperature difference between the start and end of evaporation.
It involves an increase in temperature.
A specific temperature corresponds to a given vapour pressure.

284

Ťažká

What does a vacuum leak test involve?


With the vacuum pump switched on, check whether the pressure in the system rises as a result of a leak.
With the vacuum pump running continuously, we are able to maintain the required vacuum level in the system.
If the pressure in the refrigeration system were to rise, we switch on the vacuum pump as required.
After switching off the vacuum pump, we check whether the pressure in the system rises

285

Ťažká

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


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

286

Ťažká

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


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

287

Stredne ťažká

In which appliances and systems is the installation of a permanent leak detection system required?


In equipment and systems containing at least 500 tonnes of CO₂ equivalent.
In equipment and systems containing at least 5 tonnes of CO₂ equivalent.
In equipment and systems containing at least 50 tonnes of CO₂ equivalent.
In equipment and installations containing at least 30 kg of fluorinated greenhouse gases.

288

Ťažká

In accordance with Regulation (EU) 2024/573 of the European Parliament and of the Council, a fixed leak detection system is required when:


The refrigeration equipment is operated in an enclosed space.
The installation of a fixed leak detection system is optional, but it helps to reduce the number of leak checks required on the equipment each year.
The refrigerant charge of the refrigeration equipment is at least 100 kg of ODS.
The charge of an F-gas refrigerant in a refrigeration unit is at least 500 tonnes of CO₂ equivalent.

289

Ťažká

Under Regulation (EC) No 1516/2007 and the F-gas Act, which leak detection methods may not be carried out by a person holding a Category E certificate?


Leak testing using a fluorescent dye.
Visual leak inspection.
Measuring leaks using a handheld leak detector.
Leak detection using a foaming solution.

290

Ťažká

According to the current regulation, what sensitivity must a handheld leak detector have?


5 g/year.
8 g/year.
3 g/year.
10 g/year.

291

Stredne ťažká

Which category of F-gas certificate (A1, A2, B, C, D, E) authorises the performance of leak tests on refrigeration equipment:


Only categories A1 and A2.
Category E only.
Categories D and E.
All except category D.

292

Ťažká

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


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

293

Ťažká

At what intervals should leak tests be carried out on refrigeration equipment containing more than 500 tonnes of CO₂ equivalent of fluorinated greenhouse gases that does not have a leak detection system installed?


Once every 3 months.
Once a month.
Once every 12 months.
Once every 6 months.

294

Stredne ťažká

Why is it advisable to subcool the liquid refrigerant?


This is advisable because it ensures that the liquid refrigerant, free of vapour bubbles, enters the expansion valve.
This is advisable because it allows a smaller expansion valve to be used (less superheat at the valve).
This is advisable because it allows a smaller evaporator to be used (lower refrigerant temperature at the evaporator inlet).
This is advisable because it allows a smaller condenser to be used (smaller heat exchange surface area).

295

Stredne ťažká

What should be done following repairs to a leak in the refrigeration unit of a refrigerated trailer?


A visual inspection should be carried out only on bolted and soldered joints.
You must enter the details into the equipment log (including the quantities of refrigerant recovered and used) and inform the Operator that an additional leak test must be carried out by a certified person within one month of the repair.
An invoice for the service work carried out must be issued as soon as possible.
The unit must be charged with an alternative refrigerant, started up, and the refrigerant parameters checked at the service valve located on the liquid receiver.

296

Stredne ťažká

Recovery of fluorinated greenhouse gases means:


The final decommissioning and withdrawal from service or use of a product or piece of equipment containing fluorinated greenhouse gases.
The collection and storage of fluorinated greenhouse gases originating, for example, from machinery, equipment and containers.
The reuse of fluorinated greenhouse gases following a basic purification process.
The reprocessing of fluorinated greenhouse gases to achieve their specified standard properties.

297

Stredne ťažká

Who is authorised to recover refrigerant from stationary refrigeration equipment:


The administrator of the operator’s account.
The owner of the installation.
A service technician holding an F-gas certificate in the relevant category.
The operator.

298

Stredne ťažká

Recovered refrigerants must be stored:


In a cylinder that previously contained the same type of refrigerant.
In any pressure vessel that has been officially certified.
In a specially adapted and labelled cylinder fitted with a two-way valve.
In any used refrigerant cylinder.

299

Stredne ťažká

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


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

300

Stredne ťažká

What should be done if the refrigerant recovered from the system is contaminated, e.g. with acid, air or moisture?


Add a special contaminant neutraliser to the mixture.
Purify the mixture by passing it through a particulate filter and reuse it.
Such a mixture must be handed over to a specialist authorised company for regeneration or disposal.
You should attempt to purify the mixture yourself using a dehydrating filter.

301

Stredne ťažká

What should be done if different types of refrigerants become mixed in a storage cylinder (container)?


Send this mixture to a specialist authorised company to have it neutralised.
You should attempt to separate the mixture into its individual components.
Add a special refrigerant to the mixture.
The mixture should be purified by passing it through a filter-drain and reused.

302

Stredne ťažká

How does refrigerant recovery using the Push-Pull method work?


This involves using a suction device (compressor) to ensure that the refrigerant, in liquid form, is transferred into the cylinder.
It involves using a recovery unit to draw (pull) the refrigerant vapour from the cylinder and then force it (push) into the low-pressure side of the system.
This involves injecting nitrogen from the cylinder into the unit and expelling the liquid refrigerant from the unit.
This involves the refrigerant being alternately drawn from the suction side and then from the discharge side of the refrigeration unit (compressor).

303

Stredne ťažká

What are the methods for managing waste refrigerant?


Disposal, storage.
Recycling, regeneration, disposal.
Regeneration, recovery.
Recovery, disposal.

304

Stredne ťažká

The most advantageous method of managing waste refrigerant is:


Storage.
Recycling.
Disposal.
Regeneration.

305

Stredne ťažká

The lower the evaporation temperature, ...


...the lower the density of the refrigerant and the lower the mass of the flowing refrigerant.
...the lower the refrigerant density, and the greater the cooling capacity of the compressor.
...the greater the density of the refrigerant and the mass flow rate of the flowing refrigerant.
…the greater the density of the refrigerant and the lower the mass flow rate of the refrigerant.

306

Stredne ťažká

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


They should bear only markings relating to weight and capacity.
They should bear the manufacturer’s logo and the date of manufacture.
They should bear, amongst other things, information such as: the number of the standard applied to their design, construction and testing; the identification marks of the country of approval and the inspection body; the date of the acceptance test; and the manufacturer’s and operational marks.
It is irrelevant how pressure vessels should be marked.

307

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.

308

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

309

Ľahká

What is the compressor’s compression ratio?


It is the amount of refrigerant that will be compressed in a single compressor cycle relative to the heat capacity.
It is the ratio of the discharge pressure to the suction pressure of the compressor (pk/po).
It is the ratio of the suction pressure to the discharge pressure of the compressor (po/pk).
It is the ratio of the discharge pressure to the effective capacity of the compressor (p/Vk).

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Stredne ťažká

What is compressor flooding?


Flooding the compression chamber with liquid refrigerant or oil.
A large amount of liquid refrigerant in the evaporator.
Flooding of the compressor due to rainfall.
Suction of liquid refrigerant into the compressor’s suction line.

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Stredne ťažká

To what extent do we regulate the compressor motor’s rotational speed when using a frequency converter?


Approximately from 30 to 75 Hz, which corresponds to around 60% to 150% of the cooling capacity.
From approximately 30% to 90% of capacity.
Up to a maximum of 10 per cent.
Regulating the compressor motor speed is not the same as regulating the cooling capacity.

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Ľahká

What is the theoretical displacement of a compressor?


This is the volume of refrigerant that flows through a reciprocating compressor during a single piston cycle.
The displacement of a compressor is determined by the dimensions of the cylinder – its volume (cm³)
It is the volume of refrigerant delivered by a reciprocating compressor per unit of time, usually referred to by the manufacturer as the displacement. It depends on the compressor’s geometric dimensions and rotational speed.
The displacement capacity of a compressor is expressed by the coefficient of performance (COP)

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

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Stredne ťažká

The cycle of a two-stage vapour-compression refrigeration system should have, in each stage of the system:


a compression ratio of less than 18.
a compression ratio of less than 8.
a compression ratio greater than 8.
a compression ratio of less than 6

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Stredne ťažká

Why is it necessary to seal the shafts in gland-sealed refrigeration compressors?


Because we need to prevent air from entering the compressor and we need to prevent refrigerant from leaking from the compressor.
Because it protects the compressor’s crankshaft bearing.
Because it ensures the bearing remains lubricated.
Because it prevents oil leakage.

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Stredne ťažká

When is the refrigerant sufficiently cooled?


When the liquid distributors are warm.
When the outlet from the condenser is cold.
When the evaporator is covered in frost.
When no vapour bubbles are observed forming in the liquid sight glass.

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Stredne ťažká

Why should the compressor crankcase be heated?


Heating improves the dissolution of the refrigerant in the oil, which is beneficial for its viscosity.
Heating prevents the refrigerant from dissolving in the oil.
Heating keeps the lubricating oil in a liquid state.
Heating ensures that the lubricating oil is de-watered.

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Ľahká

What is the dead volume of a compressor?


It is the space between the valve plate and the top of the piston.
It is the space between the valve plate and the bottom dead centre of the piston.
This is the space between the side surface of the piston and the cylinder.
This is the space between the bottom of the piston and the crankshaft cover.

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Stredne ťažká

What are compressor sets?


These are units consisting of two-stage compressors.
These are multiple (several) air-cooled condensers.
These consist of a larger number (several) of compressors connected in parallel and mounted on a common frame.
These are sets comprising several compressors connected in any configuration.

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Stredne ťažká

What are the advantages of compressor units?


The ability to adjust the cooling capacity as required.
Space-saving and lower energy consumption.
These are inexpensive and easy-to-install units.
Easy modification of the system.

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Stredne ťažká

What do we mean by the ‘application range’ of a compressor?


By this term, we mean the following parameters: the evaporation and condensation temperatures (to and tk), or the pressure values that determine the compressor’s application.
By this term, we mean that the compressor’s application range is determined by the evaporation temperature ‘to’ at a given ambient temperature.
By this term, we mean the following parameters: compressor capacity, type of refrigerant, and the compressor’s geometric dimensions.
By this term, we mean that the compressor’s operating range is determined by the evaporation temperature ‘to’ during operation.

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Stredne ťažká

What are the basic functions of oil in a compressor?


The oil seals the gap between the piston and the cylinder.
The oil lubricates both the bearings and the sliding surfaces of the compressor components, and cools the compressor by transferring the heat generated during compression to the compressor’s outer casing.
The oil seals any leaks that develop in the system.
The oil absorbs moisture from the refrigerant that enters the compressor.

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Stredne ťažká

What are the most effective ways of regulating the compressor’s cooling capacity?


Using an expansion valve.
By means of pressure control valves.
By changing the compressor’s displacement, by varying the rotational speed, or by deactivating individual cylinders.
By partially covering the evaporator to reduce the heat exchange surface area.

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Stredne ťažká

What does compressor bypass control involve?


High-pressure liquid refrigerant is injected on the suction side of the compressor.
Hot, high-pressure refrigerant vapour is drawn in on the suction side of the compressor.
Refrigerant in the form of cooled, high-pressure vapour is introduced into the suction line.
The bypass control is not used to regulate the compressor.

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Stredne ťažká

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


The housing of a hermetic compressor and the compressor itself form a single unit.
The casing of semi-hermetic compressors can be dismantled, whereas the casing of hermetic compressors cannot be dismantled.
Semi-hermetic compressors are characterised by the quiet operation of the entire unit.
Both types of compressors are disassemblable, and the difference lies in their varying capacities.

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Stredne ťažká

How does a scroll compressor work?


It uses two screws to compress the refrigerant.
It is a device fitted with two spirals. It is a type of positive displacement (volumetric) compressor in which compression takes place through the interaction of the two spirals.
It is a type of piston-type device.
A scroll compressor is also known as a turbo compressor.

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Stredne ťažká

What physical process takes place in the evaporator?


It cools the refrigerant flowing through it.
The medium flowing through the evaporator (glycol, water) evaporates, whilst the refrigerant condenses.
The liquid refrigerant evaporates and a small amount of it becomes superheated.
It causes the refrigerant flowing through it to condense.

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Stredne ťažká

What is the purpose of regulating the compressor’s capacity?


It ensures adequate lubrication of the compressor.
It allows the cooling capacity to be adjusted to meet requirements.
It ensures that the cooling capacity is adjusted based on condensing temperatures.
Capacity control protects the compressor from low thermal loads.

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Stredne ťažká

Why is inverter speed control suitable for refrigeration compressors?


By reducing the speed of the refrigeration compressor motor, inverter speed control improves the return oil flow to the compressor.
Inverter speed control can be used with any type of compressor to ensure adequate lubrication.
Inverter speed control reduces energy consumption only under natural conditions.
Inverter speed control enables continuous, smooth regulation of cooling capacity.

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Stredne ťažká

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


Temperature has no effect on the compressor’s cooling capacity.
It does, but only if the gas is deeply cooled.
It does, but only for reciprocating compressors.
It has a significant effect on performance.

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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?


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

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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.
This compressor condenses the refrigerant whilst the vehicle is in motion.
The compressor compresses ambient air and increases the pressure of the refrigerant.
This compressor draws in refrigerant vapour from the evaporator, compresses it and then forces it into the condenser whilst the vehicle’s engine is running.

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Stredne ťažká

Which natural fluids absorb heat from the refrigerant in the condenser?


Water and an antifreeze mixture.
Water or air.
Ammonia
Air and CO2.

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Stredne ťažká

What is the function of the condenser in refrigeration systems?


Heat released in the regenerative heat exchanger is absorbed by the condenser.
Heat from the compressor is then released into the environment via the condenser.
The heat absorbed in the evaporator and transferred during the compression process is then released into the environment via the condenser.
The heat absorbed in the evaporator is then released into the environment via the condenser

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Stredne ťažká

If the condensation temperature is higher than the critical point temperature of the refrigerant, condensation:


will not occur.
will occur provided a specially designed condenser is used.
temperature has no effect on condensation.
will always occur regardless of the temperature.

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Stredne ťažká

How does the subcooling of the refrigerant take place within a refrigeration system?


Subcooling using high-pressure hot vapour.
Subcooling using an additional heat exchanger and liquid nitrogen.
Subcooling of the liquid refrigerant in the final section of the condenser.
Subcooling of the refrigerant using oil (dissolving the refrigerant in oil).

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Stredne ťažká

What is the purpose of controlling the condenser fan speed?


Condenser fan speed control ensures that the condensing pressure is maintained at the correct level.
Condenser fan speed control reduces energy efficiency.
Condenser fan speed control safeguards against the maximum permissible condensing pressure.
Dispersion of the refrigerant in the event of a system leak.