F-Gas English Low GWP
Všetky otázky
HFC | Flammable | CO₂ | NH₃
Ľahké otázky |
Stredne ťažké otázky |
Ťažké otázky
1
Ťažká
What additional protective equipment will you use when soldering systems containing HC refrigerants?
| High-visibility jacket |
| Flammable gas detector |
| Tinted safety goggles |
| Fire blanket |
2
Ťažká
Why can’t a sealed high-pressure switch be replaced with a standard mechanical one in a system containing a flammable refrigerant?
| It is a potential source of ignition |
| Dust and moisture may enter |
| There is a risk of refrigerant leakage |
| The pressure switch setting will not be correct |
3
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 |
| 0.5 m |
| 3 m |
| 2 m |
4
Ťažká
What is the maximum safe charge for a recovery cylinder with R32 refrigerant, if it can be charged with 20 kg of R410A?
| 9 kg |
| 18 kg |
| 20 kg |
| 33 kg |
5
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?
| 1.0 kg |
| 2.5 kg |
| 1.5 kg |
| 10 kg |
6
Ťažká
How can a vacuum pump be used safely to evacuate a system containing a flammable refrigerant?
| Use an ATEX-certified vacuum pump in a well-ventilated area |
| Position the vacuum pump 3 metres above floor level |
| Fit a long hose to the pump outlet to remove HC away from the system |
| There is no need to evacuate such systems |
7
Ťažká
What protective equipment must you have in your car when transporting flammable substances?
| A fire extinguisher |
| Tinted safety goggles |
| Thick gloves |
| Fire blanket |
8
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 |
| 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 |
| 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 |
9
Ťažká
Which of the following leak detection methods cannot be used to locate an HC refrigerant leak?
| Electronic HFC leak detector |
| Leak detection foam |
| Electronic leak detector for flammable refrigerants |
| Soapy water solution |
10
Ťažká
What is the most important difference between a flammable refrigerant recovery unit and a standard one?
| Different low-pressure switch setting |
| Different connection sizes |
| A different colour for the station |
| A flammable refrigerant recovery unit has no ignition sources |
11
Ťažká
Which of the following is a source of ignition?
| Contactor |
| Defrost heating element |
| Ex-certified evaporator fan motor |
| ‘n’ type thermostat |
12
Ťažká
What substance is produced when R32 is burnt?
| Phosgene |
| Carbon monoxide |
| Hydrogen fluoride |
| Hydrochloric acid |
13
Ťažká
What type of refrigerant is R1234ze?
| Hydrocarbon |
| Hydrofluoroolefin |
| Chloro-fluoro-hydrocarbon |
| Hydrochlorofluoro-hydrocarbon |
14
Ťažká
What hazards does a Group A3 refrigerant pose?
| High toxicity, moderate flammability |
| High toxicity, high flammability |
| Low toxicity, moderate flammability |
| Low toxicity, highly flammable |
15
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)?
| 1.5 kg |
| 4.93 kg |
| 1.0 kg |
| 0.285 kg |
16
Ťažká
What is the cooling capacity of R32 compared to R410A?
| 60% |
| 75% |
| 105% |
| 130% |
17
Ťažká
Why are Ex-certified evaporator fan motors used in some systems with flammable refrigerants?
| Because they are more reliable |
| 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 |
18
Ťažká
Why is the difference in density between HC and HFC refrigerants important?
| Because it affects energy efficiency |
| Because it increases operating pressures |
| Because it affects the charging rate |
| Because it affects the charge weight |
19
Ťažká
What is the GWP value for R290?
| 7 |
| 3 |
| 675 |
| A. 0.02 |
20
Ťažká
Which of the following is not a source of ignition?
| Light switch |
| Open mechanical pressure switch |
| An Ex-certified fan motor |
| Electrical switch |
21
Ťažká
What is R290?
| Propylene |
| Butane |
| Ethane |
| Propene |
22
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?
| 1.0 kg |
| 1.5 kg |
| 2.5 kg |
| 150 g |
23
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 |
| Current consumption differs for compressors using flammable refrigerants compared to those using HFCs |
| A relay is never required for compressors using flammable refrigerants |
| The method of starting the compressor motor differs from that used with HFCs |
24
Ťažká
What is the minimum distance from the work area where HC refrigerants are used at which there must be no sources of ignition?
| 3 m |
| 5 m |
| 10 m |
| 1 m |
25
Ťažká
What is the safe charge for a recovery cylinder with R290 refrigerant, if it can be charged with 10 kg of R404A?
| 20 kg |
| 8 kg |
| 17 kg |
| 3.6 kg |
26
Ťažká
How can a vacuum pump be used safely to evacuate a system containing R290?
| Fit a long hose to the pump outlet to remove HC away from the system |
| Use an ATEX-certified vacuum pump in a well-ventilated area |
| Position the vacuum pump 3 metres above floor level |
| There is no need to evacuate systems containing R290 |
27
Ťažká
In accordance with ADR regulations, what protective equipment must you have in your vehicle when transporting flammable refrigerants?
| Fire blanket |
| Thick gloves |
| Tinted safety goggles |
| A fire extinguisher |
28
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?
| You must not desolder joints on a system containing a flammable refrigerant; they must be cut using a pipe cutter |
| 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 |
29
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?
| Recover the R1270 until a vacuum is achieved, then charge the system with nitrogen to a relative pressure of 0.1 bar g |
| 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 |
| Vent the R1270 to the outside and drain the system |
| Recover the R1270 until a vacuum is achieved |
30
Ťažká
Which of the following leak detection methods cannot be used to locate a leak of R290 refrigerant?
| Electronic leak detector for flammable refrigerants |
| Electronic HFC leak detector |
| Fluorescent dye and a UV lamp |
| Leak detection foam |
31
Ťažká
Why can’t recovery stations designed for HFCs be used with R600a?
| The low-pressure switch setting will not be suitable for R600a due to its lower operating pressure |
| 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 |
32
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 |
| 6.18 kg |
| 618 kg |
| 2.27 kg |
33
Ťažká
What type of refrigerant is R32?
| Hydrocarbon |
| Hydrofluoroolefin |
| Carbon dioxide |
| Hydrofluorocarbon |
34
Ťažká
What hazards do A2L refrigerants pose?
| High toxicity, moderate flammability |
| High toxicity, high flammability |
| Low toxicity, high flammability |
| Low toxicity, moderate flammability |
35
Ťažká
What danger is associated with the combustion of HFO or HFC refrigerants?
| Phosgene is produced |
| Citric acid is produced |
| Hydrogen fluoride is produced |
| Nitrous oxide is produced |
36
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 |
| Half |
| The same |
| Twice |
37
Ťažká
What is the GWP value for R32?
| 3 |
| 0 |
| 7 |
| 675 |
38
Ťažká
Why is the accuracy of the charge weight more important for systems critically charged with R290 compared to those using HFCs
| Because these systems never have liquid receivers |
| The charge mass is significantly lower than in an HFC system, as the density is much lower |
| Due to lower operating pressures |
| Because R290 is only used in systems with a charge of less than 150g |
39
Ťažká
Why does the condenser fan run continuously in some systems using R1270?
| To ensure that the discharge pressure never becomes excessive |
| To reduce energy consumption |
| To dilute the refrigerant in the event of a leak |
| To prevent the build-up of contaminants in the condenser |
40
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 |
41
Ťažká
What is the function of an oil separator in systems using flammable or toxic refrigerants?
| 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 |
| They are used solely to measure the moisture content of the refrigerant |
42
Ťažká
Why do CO₂ refrigeration systems require special attention when separating liquid and oil?
| CO₂ operates at high pressure, which increases the risk of compressor failure and leaks |
| CO₂ does not require lubrication, so separators are unnecessary |
| CO₂ cannot be used in systems with sight glasses |
| CO₂ is flammable, so separators cannot be used |
43
Ťažká
What is the critical pressure of CO₂ (R744)?
| Approximately 74 bar |
| Approximately 120 bar |
| Approximately 10 bar |
| Approximately 31 bar |
44
Ťažká
What characterises the transcritical process in CO₂ systems?
| It is irrelevant to the operation of the system |
| The system operates above the critical point and the refrigerant does not condense in the conventional manner |
| It occurs only at low temperatures |
| Conventional condensation occurs |
45
Ťažká
What characterises the subcritical CO₂ process?
| The absence of condensation |
| The conventional condensation process below the critical point |
| Operation above the critical point |
| The absence of evaporation |
46
Ťažká
What is the log(p)-h diagram for CO₂ used for?
| For analysing thermodynamic processes in a refrigeration system |
| To regulate pressure |
| To detect leaks |
| To measure temperature |
47
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 |
48
Ťažká
What are CO₂ saturation tables used for?
| To regulate the compressor |
| To determine the oil quantity |
| To determine the relationship between temperature and pressure at saturation |
| To measure humidity |
49
Ťažká
What does the CO₂ saturation state mean?
| Equilibrium between the liquid and vapour phases |
| Dry ice state |
| A state in which the refrigerant is only a gas |
| A state of high pressure |
50
Ťažká
When can dry ice (solid CO₂) form?
| At high pressure |
| In the event of a sudden drop in pressure and temperature below the triple point |
| At high temperature |
| During normal operation of the system |
51
Ťažká
What risks are associated with the formation of dry ice in a CO₂ system?
| Blocked pipes and system damage |
| Pressure reduction |
| No risk |
| Improved efficiency |
52
Ťažká
How does the CO₂ pressure change as the temperature rises?
| It decreases |
| It first decreases, then increases |
| Rises sharply |
| It remains the same |
53
Ťažká
Why is understanding the log(p)-h graph particularly important for CO₂?
| It doesn’t matter |
| As CO₂ systems operate in different modes (sub- and transcritical) and require detailed analysis |
| It only applies to NH₃ |
| It is only used for design purposes |
54
Ťažká
What happens to CO₂ above the critical point?
| It ceases to conduct heat |
| It transitions to a supercritical state (no distinction between liquid and gas) |
| It turns into a liquid |
| It turns into a solid |
55
Ťažká
Why do CO₂ systems require precise pressure control?
| They do not require control |
| Due to low pressures |
| Because there are no valves |
| Due to significant pressure changes with temperature fluctuations |
56
Ťažká
What is the main difference between a dry evaporator and a flooded evaporator?
| A dry evaporator does not require an expansion valve, whereas a flooded one does |
| 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 is filled with refrigerant liquid, whilst a flooded evaporator is filled with gas |
57
Ťažká
What is the typical pressure in deep-freezing systems (below −40 °C) for an evaporator in a system using R717?
| Negative pressure (vacuum), below 0 bar |
| Positive pressure, in the range of 5–10 bar |
| Atmospheric pressure, approximately 1 bar |
| A pressure varying between 10 and 20 bar |
58
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 cause rapid cooling of the atmosphere |
| They are climate-neutral |
| They are persistent, accumulate in the environment and may be toxic |
59
Ťažká
What is the basic requirement when charging a system with R717 (NH₃)?
| 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 |
| NH₃ can be charged together with air |
60
Ťažká
How should oil be handled in systems using R717?
| Oil has no effect on the system’s operation |
| 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 |
61
Ťažká
What is the correct procedure for recovering R717 from a system?
| The gas can be released into the atmosphere |
| The refrigerant can be drained into the sewer system |
| Recovery is not required |
| The refrigerant must be recovered into suitable, leak-proof tanks designed for NH₃ |
62
Ťažká
How should R717 (NH₃) be stored?
| In any open containers |
| In sealed, labelled containers, in a cool and well-ventilated place |
| Near heat sources |
| In unmarked plastic containers |
63
Ťažká
What should be done in the event of R717 contamination?
| Continue to use without restriction |
| The refrigerant must be purified or sent for disposal in accordance with regulations |
| Release into the atmosphere |
| Add water to dilute it |
64
Ťažká
What is the main hazard associated with an R717 leak during maintenance work?
| No risk whatsoever |
| Increased cooling efficiency |
| Toxic to humans and may cause chemical burns |
| Damage to electrical equipment only |
65
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 |
66
Ťažká
What role do scrubbers play in NH₃ systems?
| They increase the pressure in the system |
| They are used to measure temperature |
| Neutralises ammonia through absorption in a liquid (e.g. water) |
| They store the refrigerant |
67
Ťažká
How should the system be prepared before filling with R717?
| Check for leaks, remove air and moisture, and create a vacuum |
| The pressure must be increased above the standard level |
| There is no need to check it |
| Simply start it up |
68
Ťažká
What are the transport requirements for R717?
| It can be transported without labelling |
| 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 |
69
Ťažká
What personal protective equipment is required when working with NH₃?
| Only a safety helmet |
| Workwear only |
| Safety goggles, gloves and respiratory protective equipment |
| No requirements |
70
Ťažká
What is the main characteristic of R744 (CO₂) refrigeration systems?
| Low energy efficiency |
| Low operating pressures |
| Very high operating pressures |
| No need for regulation |
71
Ťažká
What are the requirements for piping materials in CO₂ systems?
| They may be made of any material |
| They must be able to withstand high pressures (e.g. high-grade steel) |
| It does not matter |
| They must be made exclusively from plastics |
72
Ťažká
How does a booster system work in CO₂ installations?
| It reduces the amount of refrigerant |
| It is used to store the refrigerant |
| It reduces the pressure in the evaporator |
| It utilises two stages of compression (low and medium pressure) in a single system |
73
Ťažká
What is the function of high-pressure control valves in CO₂ systems?
| They are used to store the refrigerant |
| They control the pressure on the high-pressure side and optimise system operation |
| They lower the evaporator temperature |
| They regulate oil flow |
74
Ťažká
Why is pressure optimisation in CO₂ systems crucial?
| It reduces the amount of refrigerant |
| It doesn’t matter |
| It reduces the ambient temperature |
| It enables the system to achieve maximum energy efficiency |
75
Ťažká
What role do parallel-operating compressors play in CO₂ systems?
| They enable gas recovery from the medium-pressure stage and improve efficiency |
| They lower the ambient temperature |
| It does not matter |
| They increase energy consumption |
76
Ťažká
How does an ejector work in a CO₂ system?
| It lowers the evaporator temperature |
| It uses the energy of the higher-pressure refrigerant to raise the pressure of the refrigerant from the lower stage, which improves efficiency |
| It increases the amount of refrigerant |
| Stores the refrigerant |
77
Ťažká
What is the function of liquid ejectors in CO₂ systems?
| They reduce atmospheric pressure |
| They raise the refrigerant temperature |
| They increase the amount of oil |
| They assist with liquid recovery and improve evaporator feed |
78
Ťažká
What are the characteristics of partially flooded systems in CO₂ systems?
| The presence of liquid in the evaporator, which improves heat transfer and efficiency |
| Lack of regulation |
| The absence of liquid in the evaporator |
| Low operating pressure |
79
Ťažká
What is the main risk associated with static pressure in CO₂ systems?
| A drop in temperature |
| Increased efficiency |
| A decrease in refrigerant quantity |
| A rise in pressure resulting from the refrigerant heating up whilst at rest |
80
Ťažká
How can standstill pressure in CO₂ systems be reduced?
| By increasing the temperature |
| By shutting down the system completely |
| By increasing the refrigerant charge |
| By using parallel compressors and external cooling systems |
81
Ťažká
What does ‘stagnation’ of a refrigeration system mean in the context of CO₂?
| Improved efficiency |
| A drop in temperature |
| A lack of refrigerant flow, which can lead to increased pressure and safety risks |
| Normal system operation |
82
Ťažká
Why do CO₂ systems require more advanced automation than traditional systems?
| Due to the need for precise control of pressure and temperature |
| Because there are no valves |
| They do not require automation |
| Due to low pressures |
83
Ťažká
What must be included on the label of a cylinder containing a flammable refrigerant?
| Net weight only |
| The name of the refrigerant, the hazard symbol and basic safety information |
| Agent name only |
| Information about the cylinder owner |
84
Ťažká
Why does the absence of a ‘flammable agent’ label on the system pose a significant hazard?
| It reduces the system’s efficiency |
| It has no significant impact on safety |
| It may lead to the use of tools that are a source of ignition |
| It may lead to the incorrect selection of oil |
85
Ťažká
Which set of information on the label of a flammable agent cylinder is crucial from a safety perspective?
| Manufacturer’s name and country of origin |
| Cylinder colour and date of manufacture |
| Gross weight and batch number |
| Name of the substance, hazard pictogram, UN number |
86
Ťažká
What is the requirement regarding the labelling of an installation containing a flammable substance?
| The labelling must indicate the type of substance and the flammability hazard |
| Colour-coding of pipes is sufficient |
| Labelling is required only in technical rooms |
| Labelling is not required for hermetically sealed systems |
87
Ťažká
What are the potential consequences of using unsuitable connections in a system containing a flammable substance?
| Merely installation difficulties |
| Merely a reduction in efficiency |
| No impact on safety |
| Risk of leakage and the formation of an explosive mixture |
88
Ťažká
What is the purpose of installing gas detectors in a room with a refrigeration system?
| Early detection of refrigerant leaks and prevention of health risks |
| Regulating compressor capacity |
| Measuring the refrigerant temperature |
| Monitoring pipe pressure |
89
Ťažká
How often should gas detection sensors in the service room be checked?
| Once every 5 years |
| Only after a leak has occurred |
| In accordance with the manufacturer’s instructions and applicable health and safety regulations |
| Before each start-up of the unit |
90
Ťažká
Where should a gas detector be positioned in accordance with EN 378?
| On the ceiling if the gas is lighter or heavier than air; near the floor if it is lighter or heavier |
| Anywhere in the room |
| Near the control panel |
| Only at the entrance to the room |
91
Ťažká
How should an employee respond when a gas alarm is triggered?
| Leave the room immediately and notify their supervisor |
| Carry on working until they see a leak |
| Switch off the system and wait for the alarm to stop |
| Reduce the pressure in the system |
92
Ťažká
What safety checks should be carried out when installing a new refrigeration system?
| The colour of pipes and hoses |
| Only the compressor power |
| The presence of health and safety signage, adequate ventilation and gas detectors |
| Is the air filter new? |
93
Ťažká
Gas detectors should be installed in rooms where:
| The room is less than 5 m² |
| Any refrigerant is present, regardless of the quantity |
| The amount of refrigerant exceeds a specified permissible threshold |
| Ventilation is natural |
94
Ťažká
What is the minimum number of emergency exits in a plant room (refrigeration plant room) and how should they be signposted?
| One exit, clearly marked in the direction of escape |
| One exit with an information sign about the refrigerant |
| Exits do not need to be signposted if the room is small |
| At least two exits, but signage is optional |
95
Ťažká
Which measure, when installing a system using a flammable refrigerant, improves its energy efficiency?
| Restriction of ventilation |
| Thorough leak testing and vacuuming |
| Increasing the refrigerant charge |
| No leak test |
96
Ťažká
How do leaks affect systems using flammable refrigerants?
| They lower the temperature |
| They cause refrigerant loss, reduced efficiency and a fire hazard |
| Have no effect |
| They improve efficiency |
97
Ťažká
Why is it important to limit the amount of refrigerant in HC systems?
| It increases efficiency |
| It has no effect |
| It lowers the temperature |
| It reduces the risk of explosion and improves the system’s operational safety |
98
Ťažká
Why is the cleanliness of heat exchangers in HC systems important?
| Causes leaks |
| It improves heat transfer and reduces energy consumption |
| It doesn’t matter |
| It increases the pressure |
99
Ťažká
What maintenance measures improve the efficiency of a system using a flammable refrigerant?
| Disabling safety devices |
| Regular checks for leaks and operating parameters |
| Increasing the refrigerant charge |
| Lack of servicing |
100
Ťažká
How does the correct selection of components affect a system using a flammable refrigerant?
| It lowers the temperature |
| It doesn’t matter |
| It increases the amount of refrigerant |
| It ensures safe and optimal operation and minimises energy losses |
101
Ťažká
Why is it important to use the correct service tools in HC systems?
| It doesn’t matter |
| It ensures operational safety and reduces refrigerant losses |
| Causes leaks |
| It increases energy consumption |
102
Ťažká
How does pipe insulation affect the efficiency of systems containing HC?
| It doesn’t matter |
| Causes leaks |
| It reduces energy losses and improves efficiency |
| It increases the pressure |
103
Ťažká
Which safety class applies to R744?
| A2 |
| A1 |
| B2L |
| A3 |
104
Ťažká
In an R744 system operating in supercritical mode, the refrigerant entering the evaporator expansion valve is...
| Saturated vapour at intermediate pressure |
| A subcooled liquid |
| A two-phase mixture at intermediate pressure |
| A supercritical fluid |
105
Ťažká
In R744 supercritical systems, the gas cooler outlet valve controls:
| The gas cooler fans |
| The outlet temperature of the gas cooler |
| The pressure in the gas cooler |
| The inlet temperature to the gas cooler |
106
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 mixes very well with compressor oil and easily returns to the compressor |
| 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 |
107
Ťažká
What is the main reason for using K65 copper tubing in some R744 systems?
| They bend easily |
| They come in a wider range of diameters |
| They have good low-temperature performance |
| They can withstand higher pressures |
108
Ťažká
Which of the following statements is correct regarding the installation of Schrader valves?
| All Schrader valve cores are suitable for all refrigerants |
| Schrader valves must not be used in R744 systems |
| When brazing the valve body to the system, the core must be removed, then refitted and tightened to the correct torque |
| Hydrocarbons leak through Schrader valves |
109
Ťažká
Which refrigerant can be detected using phenolphthalein paper?
| R744 |
| R1270 |
| R717 |
| R1234ze |
110
Ťažká
How does a refrigerant shortage affect the high-pressure side of the system (without discharge pressure regulation)?
| 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 |
| The discharge pressure will be lower, and the subcooling will be lower |
| Discharge pressure will be lower, subcooling will be higher |
111
Ťažká
What is the benefit of using helium as a tracer gas in nitrogen during a pressure test?
| It is non-flammable |
| It has smaller molecules and diffuses more easily |
| It has a higher pressure than pure nitrogen |
| It has a distinct odour |
112
Ťažká
Why should an R744 system that has been drained be initially charged with the refrigerant in gaseous form?
| To prevent the drain valve from opening |
| To prevent damage to the compressor |
| To ensure that R744 is charged slowly |
| To prevent the formation of dry ice |
113
Ťažká
If an R744 system contains moisture because it has not been properly drained, what is the likely consequence?
| Reduced cooling capacity |
| 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 |
| Excessively high discharge pressure |
114
Ťažká
Which system may require manual oil recovery?
| R744 cascade system |
| Secondary system using R744 |
| An R717 system |
| Supercritical ‘booster’ system using R744 |
115
Ťažká
The pressure of R744 at a saturation temperature of 20 °C is approx.
| 90 bar g |
| 14 bar g |
| 25 bar g |
| 56 bar g |
116
Ťažká
Which refrigerant is lighter than air?
| R1234ze |
| R744 |
| R1270 |
| R717 |
117
Ťažká
What hazards are associated with a Class A3 safety agent?
| Lower toxicity, does not propagate flames |
| High flammability, lower toxicity |
| Slightly flammable, lower toxicity |
| High toxicity, does not propagate flames |
118
Ťažká
18 What is the GWP of R32 (according to AR4)?
| 675 |
| 0 |
| 3945 |
| 6 |
119
Ťažká
What factors are taken into account when determining the maximum charge for comfort air-conditioning/heating applications?
| Practical limit, room volume |
| Lower flammability limit, room volume |
| Practical limit, height of the indoor unit, floor area |
| Lower flammability limit, height of the indoor unit, floor area |
120
Ťažká
What compressor displacement is required for R1270, relative to R404A compressors for the medium-temperature range (cold store)?
| 150% |
| 600% |
| 50% |
| Similar |
121
Ťažká
At an ambient temperature of 25°C, the standby pressure in the low-pressure stage of an R744 cascade system will typically be…
| Higher than the maximum permissible pressure in the low-pressure stage |
| The same as the pressure set on the relief valve |
| 27.5 bar g |
| The same as the high-pressure setting on the pressure switch |
122
Ťažká
What is the correct definition of critical temperature?
| The temperature above which there are no distinct liquid and gaseous phases |
| The temperature at which the vapour pressure of a liquid is equal to the ambient pressure surrounding the liquid |
| The temperature at which, for certain substances, electrical resistance is zero |
| The temperature at which a substance changes from a gaseous to a solid state |
123
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 during a phase change |
| loses heat at constant temperature and pressure |
124
Ťažká
R717 is highly corrosive to
| aluminium |
| stainless steel |
| titanium |
| copper |
125
Ťažká
What is the effect of repeatedly opening the relief valve?
| The relief pressure rises |
| The relief pressure drops |
| The valve will not open |
| The valve remains fully open continuously |
126
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 = (P1 × T2)/T1 |
| P2 = (P1 × T1)/T2 |
| P2 = T2/(P1 × T1) |
| P2 = T1/(P1 × T2) |
127
Ťažká
What is the recommended alarm level for fixed leak detection systems for R717?
| 500,000 ppm |
| 50,000 ppm |
| 5,000 ppm |
| 500 ppm |
128
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 |
| Because compressors with a separate motor are cheaper |
| To reduce the condensing pressure |
| Because NH₃ reacts with the motor windings and hermetic compressors are not used |
129
Ťažká
Which type of compressor is most commonly used in large ammonia systems?
| A reciprocating or screw compressor |
| Hermetic scroll |
| Diaphragm compressor |
| Rotary vane compressor |
130
Ťažká
How is the capacity of a piston compressor regulated in NH₃ systems?
| By reducing the refrigerant charge |
| By unloading the cylinders or changing the rotational speed |
| By increasing the condensing pressure |
| Solely by adjusting the oil volume |
131
Ťažká
How is the capacity of a screw compressor most commonly controlled?
| By closing the suction valve |
| By using a slide valve |
| By adjusting the oil level |
| By changing the type of oil |
132
Ťažká
When is two-stage compression used in NH₃ systems?
| Only with water-cooled condensers |
| Exclusively in small systems |
| At small temperature differences |
| At very low vapour pressures and high pressure differentials |
133
Ťažká
What is the advantage of two-stage compression over single-stage compression?
| Lower efficiency |
| No need for a separator |
| Higher efficiency and lower discharge temperature |
| Higher energy consumption |
134
Ťažká
How does an evaporative condenser used in NH₃ systems work?
| It transfers heat only to the air |
| Operates without a fan |
| It utilises the evaporation of water to increase cooling efficiency |
| It does not require a water supply |
135
Ťažká
What is the function of the liquid separator in an NH₃ system?
| Increases the discharge temperature |
| It prevents liquid from entering the compressor |
| It separates oil from the refrigerant |
| Regulates the condensing pressure |
136
Ťažká
What is the purpose of monitoring the liquid level in the separator?
| To increase the oil volume |
| To reduce the condensing temperature |
| To control the condenser fan |
| To maintain the correct refrigerant level and prevent the compressor from flooding |
137
Ťažká
What is the role of the float switch in NH₃ systems?
| It regulates the condensation temperature |
| It monitors the liquid level in the tank or separator |
| It controls the fan’s operation |
| It is used to detect leaks |
138
Ťažká
What is a thermosiphon in NH₃ systems?
| A type of evaporator |
| A defrosting device |
| A type of safety valve |
| An oil circulation system utilising differences in pressure and temperature |
139
Ťažká
Why are oils that are immiscible with the refrigerant used in NH₃ systems?
| Because NH₃ does not mix with most compressor oils |
| To reduce the pressure |
| To increase the amount of refrigerant |
| Because the oil mixes only with water |
140
Ťažká
What is the main function of an oil separator in NH₃ systems?
| To separate the oil from the refrigerant and return the oil to the compressor |
| Removing moisture from the system |
| To increase fan efficiency |
| To lower the condensation temperature |
141
Ťažká
Which NH₃ system features direct evaporation of the refrigerant in the evaporator?
| Indirect system |
| Glycol system |
| Thermosiphon system |
| Direct expansion (DX) system |
142
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 |
143
Ťažká
What is the main difference between a direct and an indirect system?
| In a direct system, there is no evaporator |
| In an indirect system, NH₃ flows directly into the space being cooled |
| In an indirect system, NH₃ cools an intermediate medium (e.g. glycol), which in turn cools the load |
| In an indirect system, no compressor is used |
144
Ťažká
Which parts of refrigeration systems must be inspected on a mandatory and regular basis in accordance with EU Regulation 1516/2007?
| Compressor connections, 2. connections on the liquid refrigerant tank |
| Only compressor connections, as these are subject to vibration. |
| Connections on the condenser, as there is high pressure and the refrigerant is in liquid form |
| Fittings, 2. valves, 3. seals, 4. parts/components exposed to vibration, 5. connections at safety devices. |
145
Ťažká
In accordance with EU Regulation 1516/2007, there are several methods of leak testing. What are these methods called?
| 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 methods for quality control of supplied materials and leak testing methods that do not involve quality control of supplied materials. |
| We distinguish between physical and chemical methods. |
146
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 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. |
| The check may only be carried out by a person who has previously carried out such a check. |
147
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 that such a test is technically feasible. |
| 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 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). |
148
Ťažká
In accordance with EU Regulation 1516/2007, which leak testing methods are classified as direct leak testing methods?
| Leak test using nitrogen with a tracer gas, an electronic detector and pressure measurement. |
| Leak test following the creation of a vacuum and leak detection using a foaming solution. |
| 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 testing by measuring pressure changes and the method of submerging the device/system in water. |
149
Ťažká
In accordance with EU Regulation 1516/2007, which methods are classified as indirect leak testing methods?
| Leak detection using a UV tracer. |
| This method is based on the analysis of the following parameters: pressure, temperature, operating pressure, liquid level, oil leakage, etc. |
| This method is based on electronic leak detection. |
| It utilises pressure and temperature measurements, as well as an ultrasonic method. |
150
Ťažká
What does a vacuum leak test involve?
| 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 |
| With the vacuum pump running continuously, we are able to maintain the required vacuum level in the system. |
| With the vacuum pump switched on, check whether the pressure in the system rises as a result of a leak. |
151
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. |
152
Ťažká
How often should leak tests be carried out on equipment containing 7 kg of R404A refrigerant (27.45 tonnes of CO₂ equivalent)?
| Only when servicing the unit. |
| At least once every 12 months. |
| Once every six months. |
| On initial commissioning. |
153
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. |
154
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 detection using a foaming solution. |
| Visual leak inspection. |
| Measuring leaks using a handheld leak detector. |
| Leak testing using a fluorescent dye. |
155
Ťažká
According to the current regulation, what sensitivity must a handheld leak detector have?
| 8 g/year. |
| 5 g/year. |
| 3 g/year. |
| 10 g/year. |
156
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 the next periodic inspection. |
| Immediately after the repair. |
| Between 24 hours and 1 month after the repair. |
| At any time. |
157
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 a month. |
| Once every 6 months. |
| Once every 12 months. |
| Once every 3 months. |