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 in the International System of Units (SI)?
| N |
| lb (pound) |
| t |
| kg |
2
Stredne ťažká
What process takes place in the condenser of a refrigeration system?
| The refrigerant rejects only the heat generated in the compressor |
| The refrigerant absorbs heat from the surroundings and evaporates |
| Hot vapour discharged by the compressor is desuperheated, condensed, and the resulting liquid is slightly subcooled |
| The secondary fluid (glycol, water) condenses while the refrigerant evaporates |
3
Stredne ťažká
What mainly determines the condensing temperature of an air-cooled condenser?
| The ambient (inlet) air temperature |
| The evaporating temperature |
| The superheat |
| The compressor discharge temperature |
4
Stredne ťažká
Why does heat flow from the condenser to the surroundings?
| Because the pressure in the condenser is lower than ambient |
| Because HFC refrigerants attract heat from the surroundings |
| Because the condensing temperature is higher than the ambient temperature, and heat flows spontaneously from a warmer to a colder body (second law of thermodynamics) |
| Because the compressor pushes heat directly into the surroundings |
5
Stredne ťažká
What should you mainly pay attention to when operating a condenser?
| Its general condition and the cleanliness of the heat-exchange surfaces |
| That the inlet air temperature is lower than the outlet air temperature |
| The colour of the condenser casing |
| That the outlet air temperature is higher than the condensing temperature |
6
Stredne ťažká
What criteria should be considered when selecting a suitable condenser?
| Only own experience and the dimensions |
| The required capacity of the condenser and the technical specifications declared by the manufacturer |
| Fan noise, connection diameters and colour |
| Only the size and number of fans |
7
Stredne ťažká
How do contaminants (dust, particulates, deposits) affect the performance and efficiency of heat exchange surfaces in condensers?
| Contaminants do not significantly affect the efficiency and effectiveness of the heat exchange surfaces in condensers. |
| Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause an increase in condensing temperature and pressure, which in turn leads to a reduction in the condenser’s efficiency. |
| Contaminants increase the heat transfer area and reduce the condensing pressure. |
| Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause a reduction in condensing pressure. |
8
Stredne ťažká
How does the capacity of an air-cooled condenser change when it becomes dirty?
| It increases because the fan speed rises |
| It remains unchanged |
| It increases |
| It decreases |
9
Stredne ťažká
What is the main consequence of heavy frost on an air-cooling evaporator?
| Reduced heat transfer and airflow, resulting in a drop in cooling capacity and evaporating temperature |
| A rise in evaporating pressure |
| A rise in the cooled-air temperature with no effect on capacity |
| An increase in condenser subcooling |
10
Stredne ťažká
What happens when the evaporation temperature drops?
| The compressor’s cooling capacity decreases. |
| The discharge temperature decreases. |
| The condenser fan speed increases. |
| The compressor’s cooling capacity increases. |
11
Stredne ťažká
When is natural (off-cycle, air) defrosting possible?
| Only in freezer rooms below −18 °C |
| When the air passing through the cooler is above 0 °C |
| Never – electric heaters must be used in every air cooler |
| Only in coolers fitted with speed-controlled fans |
12
Stredne ťažká
When does frost form on the surface of an air-cooling evaporator?
| Only when the system runs continuously |
| When the evaporator surface temperature is below 0 °C and below the dew point of the air |
| Always, in every air cooler |
| Only when the room air temperature falls below 0 °C |
13
Stredne ťažká
In extensive pipework systems, flash gas (secondary evaporation) in the liquid line can be prevented by…
| …additional subcooling of the liquid |
| …increasing the length of the liquid line |
| …insulating the discharge line between the compressor and the condenser |
| …using smaller-diameter pipes |
14
Stredne ťažká
How does hot gas defrosting of the evaporator work?
| This involves reversing the direction of rotation of the compressor. |
| We switch on the gas heater directed at the evaporator. |
| Heated vapour (hot gas) from the compressor is directed into the evaporator piping. |
| We swap the outlet and inlet sides of the evaporator. |
15
Stredne ťažká
What is the function of the evaporator in a refrigeration system?
| It ensures that the refrigerant is superheated over the largest possible heat exchange surface area. |
| It evaporates the water flowing through the evaporator. |
| It cools the refrigerant. |
| It transfers heat from the medium being cooled to the boiling refrigerant. |
16
Stredne ťažká
What condition must electric heaters for evaporator defrosting meet?
| They must have good thermal contact with the heat-exchange surface (e.g. inserted in the fin block) |
| Heat from the heaters must be carried by the running fans |
| They must be located beneath the evaporator |
| They must be in direct contact with the refrigerant |
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 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. |
| ensures the even distribution of the refrigerant discharged by compressors connected in parallel. |
18
Stredne ťažká
What defrosting methods are used for air coolers?
| Electric only – other methods are not permitted in refrigeration |
| Natural only – other methods are ineffective and uneconomic |
| Only by switching off the fans with the compressor running |
| Electric, hot gas, water spray and natural (at positive temperatures) |
19
Stredne ťažká
The boiling point of a liquid rises when the pressure above the liquid…
| …remains constant |
| …rises |
| …varies depending on the ambient temperature |
| …falls |
20
Stredne ťažká
MOP in thermostatic expansion valves stands for:
| maximum operating pressure. |
| maximum pressure switch protection. |
| minimum flow opening. |
| self-cleaning of the valve in the event of moisture in the refrigerant freezing. |
21
Stredne ťažká
The function of a thermostatic expansion valve (TEV) is:
| to adjust the evaporating pressure in the condenser |
| to meter refrigerant into the evaporator according to the superheat of the vapour leaving the evaporator |
| to maintain a constant compressor suction pressure |
| to maintain a constant condensing pressure |
22
Stredne ťažká
What type of compressor motor can be used with a capillary tube?
| A low-speed motor |
| A high-starting-torque motor must be used |
| An electronically commutated motor |
| A low-starting-torque motor (pressures equalise during standstill) |
23
Stredne ťažká
What does a thermostatic expansion valve control?
| The mass flow of refrigerant fed into the evaporator |
| The temperature in the cold room |
| The discharge temperature |
| The condensing pressure |
24
Ľahká
The refrigerant absorbs heat when…
| …it freezes |
| …it condenses |
| …it evaporates |
| …it is subcooled |
25
Stredne ťažká
What does the manufacturer state as the factory setting of a thermostatic expansion valve?
| the degree to which the valve is filled with refrigerant liquid. |
| the degree of refrigerant expansion. |
| the superheat value during valve operation. |
| the static superheat of the valve. |
26
Stredne ťažká
Where is a new or repaired system with an expansion valve and liquid receiver charged?
| In the liquid phase on the high-pressure side, with the compressor stopped |
| Anywhere – the charging point does not matter |
| Through the capillary tube outlet during normal system operation |
| In the liquid phase into the compressor suction, with the compressor running |
27
Stredne ťažká
What does a thermostatic or electronic expansion valve control?
| The evaporating pressure – closing below the set point |
| The compressor speed |
| Subcooling, by adjusting condensing pressure |
| The amount of refrigerant fed to the evaporator according to superheat |
28
Stredne ťažká
What does the MOP function of thermostatic expansion valves mean?
| The valve limits the maximum evaporating (suction) pressure, protecting the compressor motor from overload, e.g. after defrost |
| The valve limits subcooling |
| The valve maintains a constant condensing pressure |
| The valve prevents motor overheating by injecting liquid into the compressor |
29
Stredne ťažká
The lower the liquid temperature upstream of the expansion valve, (at the same mass flow)…
| …the higher the specific refrigerating effect qo [kJ/kg] and the higher the cooling capacity Qo |
| …the lower qo and the lower energy efficiency |
| …the lower qo, with Qo unchanged |
| …the lower qo and the lower Qo |
30
Stredne ťažká
How should the MOP point of an expansion valve be selected relative to the highest normal evaporating temperature?
| About 7 K lower than that temperature |
| A few kelvin higher (approximately 7 K) |
| Higher by approx. 20 K |
| Freely – the MOP value is irrelevant |
31
Stredne ťažká
What is the function of the suction pressure regulator?
| It prevents a drop in suction pressure and, if necessary, shuts down the refrigeration system. |
| It maintains the evaporation 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. |
32
Stredne ťažká
What is the function of the valve regulating water flow through the condenser?
| To maintain the condensing pressure at the highest possible level. |
| To maintain the water temperature at the highest level. |
| To maintain the condensing pressure at the lowest possible level. |
| To maintain the condensing pressure at a constant level. |
33
Stredne ťažká
The use of a refrigerant distributor requires a thermostatic expansion valve ...
| ... with internal pressure equalisation. |
| ... with an adsorption-type sensor filling. |
| ... with external pressure equalisation. |
| ... with a MOP function. |
34
Stredne ťažká
What properties should good insulation materials have?
| An antistatic coating |
| High thermal conductivity |
| The ability to absorb large amounts of moisture |
| Low thermal conductivity (and low water absorption, vapour tightness) |
35
Stredne ťažká
When is refrigerant vapour superheated?
| When the pressure on the discharge side is higher than on the suction side |
| When the compressor motor temperature rises excessively |
| When its temperature is higher than the saturation temperature corresponding to its pressure |
| When the evaporating temperature is lower than the ambient temperature |
36
Stredne ťažká
How can you check whether the liquid refrigerant is reaching the expansion valve without vapour bubbles?
| 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. |
| We check using a liquid pressure gauge. |
37
Stredne ťažká
Where does the liquid line run?
| Between the compressor and the condenser |
| Between the evaporator and the suction-line heat exchanger |
| Between the evaporator and the compressor |
| From the condenser (liquid receiver) to the expansion valve |
38
Stredne ťažká
What is the function of the liquid receiver in a refrigeration system?
| To further subcool the condensed refrigerant |
| To act as a reserve when the required charge is unknown |
| To collect liquid refrigerant and excess oil |
| To store refrigerant and compensate for changes in the circulating charge as the heat load varies |
39
Stredne ťažká
What is the purpose of the liquid receiver during service work?
| It allows pump-down and temporary storage of the refrigerant |
| It is a reserve when the installer does not know the required charge |
| It further subcools the refrigerant before the expansion valve |
| It collects excess oil circulating in the system |
40
Stredne ťažká
Where should the liquid receiver be installed?
| It should be fitted just before the compressor. |
| It should be fitted between the compressor and the condenser. |
| It should be installed downstream of the condenser, upstream of the expansion valve. |
| It should be fitted after the evaporator. |
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 regulates the condensing pressure. |
| It opens when the suction pressure upstream of the compressor drops. |
| It closes when the suction pressure upstream of the compressor drops. |
42
Stredne ťažká
The use of microchannel heat exchangers, compared with conventional heat exchangers made of copper tubes and fins, results in:
| A reduction in the system’s energy efficiency. |
| There is no effect whatsoever on either the amount of refrigerant or energy efficiency. |
| A reduction in refrigerant charge and, typically, higher energy efficiency. |
| An increase in the amount of refrigerant in the system and an increase in condensing pressure. |
43
Stredne ťažká
Which refrigerants belong to the HFC group?
| R22, R401A. |
| R134a, R32, R22, R507A, R290. |
| R134a, R404A, R507A, R410A. |
| R11, R12, R502. |
44
Stredne ťažká
Which refrigerants belong to the HFO group?
| R1234yf, R1234ze(E). |
| R22, R12. |
| R134a, R404A. |
| R134a, R290. |
45
Stredne ťažká
What are the characteristics of R410A refrigerant compared to R407C refrigerant?
| 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. |
| The saturation pressure of R407C is 150% higher than that of R410A. |
46
Stredne ťažká
What does the TEWI indicator define?
| Total Equivalent Warming Impact: the sum of direct emissions (leakage and refrigerant losses at disposal) and indirect emissions (CO₂ from generating the energy consumed by the equipment) over its lifetime |
| The ability of the ozone layer to recover |
| The impact of a refrigerant on the ozone layer |
| The global warming potential of a gas relative to CO₂ over a 100-year horizon |
47
Stredne ťažká
What are the characteristics of R452A compared with R404A?
| The temperature glide of R452A is half that of R404A |
| Both are azeotropic and have no temperature glide |
| It is a flammable and toxic single-component HFC |
| It is a non-flammable (A1) HFC/HFO blend with properties similar to R404A and a GWP about 45% lower |
48
Stredne ťažká
What distinguishes R1234yf from R134a?
| Higher toxicity |
| It is mildly flammable (class A2L), whereas R134a is non-flammable (A1) |
| A higher critical temperature |
| A higher normal boiling point |
49
Stredne ťažká
How does CO₂ (R744) compare with R134a?
| It has a lower critical temperature, much higher operating pressures and a much higher volumetric cooling capacity (smaller compressors and pipes) |
| Unlike R134a, it is an azeotropic mixture |
| Its temperature glide is 7 K greater than that of R134a |
| It has identical properties and is a drop-in replacement for R134a |
50
Stredne ťažká
Which of the following is NOT a fluorinated greenhouse gas?
| Hydrofluorocarbons (HFCs). |
| Carbon dioxide (CO₂). |
| Sulphur hexafluoride (SF6). |
| Perfluorocarbons (PFCs). |
51
Ťažká
What additional protective equipment will you use when brazing systems containing HC refrigerants?
| A high-visibility vest |
| A flammable gas detector |
| Latex gloves |
| Ear defenders |
52
Ťažká
Why can’t a sealed high-pressure switch be replaced with a standard mechanical one in a system containing a flammable refrigerant?
| Dust and moisture may enter |
| It is a potential source of ignition |
| The pressure switch setting will not be correct |
| There is a risk of refrigerant leakage |
53
Ťažká
What is the minimum (recommended) distance from a work area with HC refrigerants within which there must be no sources of ignition?
| 1 m |
| 2 m |
| 0.5 m |
| 3 m |
54
Ťažká
What is the maximum safe R32 fill of a recovery cylinder approved for flammable gas that holds 20 kg of R410A (the liquid density of R32 is about 8-10% lower)?
| 9 kg |
| 20 kg |
| 18 kg |
| 33 kg |
55
Ťažká
What is the maximum charge of an A3 refrigerant for a hermetic display cabinet with an integral condenser located in the ground-floor sales area of a supermarket?
| 1.0 kg |
| 0,494 kg |
| 10 kg |
| 2.5 kg |
56
Ťažká
How can a vacuum pump be used safely to evacuate a system containing a flammable refrigerant?
| Position the pump at least 3 m above floor level |
| Place the pump directly on the floor, as low as possible |
| Ignition-source-free pump, good ventilation, exhaust to a safe place |
| Such systems need not be evacuated before charging |
57
Stredne ťažká
What is the greenhouse effect?
| Greenhouse gases absorb and re-emit the Earth's infrared radiation, warming the lower atmosphere |
| Dust in the atmosphere reflects sunlight, lowering the average surface temperature |
| Chlorine compounds destroy stratospheric ozone, increasing UV radiation at the surface |
| Clouds reflect ultraviolet radiation, which makes the air near the surface warmer |
58
Ťažká
What safety measure must you carry in your vehicle when transporting flammable refrigerant cylinders?
| A fire blanket |
| A fire extinguisher |
| Tinted safety goggles |
| Thick gloves |
59
Ťažká
How would you prepare a 10 kg R32 water chiller located outdoors for debrazing its joints?
| Vent the R32 outdoors and purge the system |
| Recover the R32 to a vacuum, then fill the system with nitrogen to a slight positive pressure (approx. 0.1 bar g) |
| Vent the R32 outdoors, then fill and vent the system with nitrogen three times |
| Recover the R32 to a vacuum and start desoldering immediately |
60
Stredne ťažká
What is R1270?
| n-Butane |
| Propane |
| Propene (propylene) |
| Isobutane |
61
Ťažká
Which of the following leak detection methods should NOT be used to locate an HC refrigerant leak?
| Electronic leak detector for flammable refrigerants |
| Leak detection foam |
| Soapy water solution |
| Electronic HFC leak detector |
62
Ťažká
What is the most important difference between a flammable refrigerant recovery unit and a standard one?
| A different colour for the station |
| Different connection sizes |
| Different low-pressure switch setting |
| A flammable refrigerant recovery unit has no ignition sources |
63
Ťažká
Which of the following is a source of ignition?
| A sealed NTC temperature sensor |
| A contactor (sparking contacts) |
| An Ex-certified fan motor |
| An 'n'-type (non-sparking) thermostat |
64
Ťažká
What particularly hazardous substance is formed when R32 burns?
| Hydrogen chloride (HCl) |
| Phosgene |
| Hydrogen fluoride (HF) |
| Sulphur dioxide (SO₂) |
65
Ťažká
What type of refrigerant is R1234ze(E)?
| HC (hydrocarbon) |
| HCFC (hydrochlorofluorocarbon) |
| CFC (chlorofluorocarbon) |
| HFO (hydrofluoroolefin) |
66
Ťažká
What hazards does a safety group A3 refrigerant pose?
| Higher toxicity, moderate flammability |
| Higher toxicity, higher flammability |
| Lower toxicity, moderate flammability |
| Lower toxicity, higher flammability |
67
Ťažká
According to EN 378, what is the maximum R290 charge in a cold room measuring 5 m × 3 m × 2.5 m (LFL of R290 = 0.038 kg/m³, access category a, location class I, no additional measures))?
| 1.0 kg |
| 4.93 kg |
| 0.285 kg |
| 1.5 kg |
68
Ľahká
What does the GWP indicator mean?
| The ability of a substance to restore the ozone layer |
| The annual rise in mean air temperature caused by the emission of 1 kg of the gas |
| Ozone depletion potential |
| Global Warming Potential: the climate warming impact of 1 kg of a gas compared with 1 kg of CO₂ (GWP = 1) over a defined time horizon, usually 100 years |
69
Ťažká
What is the approximate ratio of the volumetric cooling capacity of R32 to that of R410A (same compressor and conditions)?
| approx. 0.6 |
| approx. 1.3 |
| approx. 1.05–1.1 |
| approx. 0.75 |
70
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 |
71
Ťažká
Why is the density difference between HC and HFC refrigerants important?
| An HC charge in kg is roughly half that of an HFC |
| Because HCs operate at much higher pressures |
| Because HCs must be charged much more slowly than HFCs |
| Because it determines the system's energy efficiency |
72
Ťažká
What is the GWP of R290 according to Annex VI to Regulation (EU) 2024/573?
| 150 |
| 7 |
| 0.02 |
| 675 |
73
Ťažká
Which of the following is NOT a source of ignition?
| An unsealed mechanical pressure switch |
| An Ex-certified fan motor |
| An electrical switch |
| A light switch |
74
Ťažká
What is R290?
| Isobutane |
| Propane |
| Propene (Propylene) |
| Butane |
75
Ťažká
What is the maximum A2L charge for a hermetic display cabinet with integral condenser in the ground-floor sales area of a supermarket?
| 1.2 kg |
| 1.5 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 |
| The method of starting the compressor motor differs from that used with HFCs |
| Current consumption differs for compressors using flammable refrigerants compared to those using HFCs |
77
Ťažká
What is the minimum (recommended) distance from a work area with HC refrigerants within which there must be no ignition sources?
| 1 m |
| 3 m |
| 10 m |
| 5 m |
78
Ťažká
A recovery cylinder holds 10 kg of R404A (filling ratio 0.82 kg/l). What is the maximum R290 charge for this cylinder (propane filling ratio 0.43 kg/l per ADR P200)?
| approx. 17 kg |
| 20 kg |
| approx. 8 kg |
| approx. 5.2 kg |
79
Stredne ťažká
How do refrigeration systems contribute to the greenhouse effect?
| Only through the heat rejected by the condenser |
| Through oil emitted into the atmosphere from the condenser and filter |
| Indirectly (through energy consumption) and directly (through emissions of refrigerant into the atmosphere) |
| Only through CO₂ given off by the compressor motor |
80
Ťažká
How can a vacuum pump be used safely to evacuate a system containing R290?
| Ignition-source-free pump, good ventilation, exhaust to a safe place |
| Position the pump at least 3 m above floor level |
| R290 systems need not be evacuated before charging |
| Place the pump directly on the floor, as low as possible |
81
Ťažká
Under ADR, what equipment must you carry in your vehicle when transporting flammable refrigerant cylinders (under the 1.1.3.6 exemption)?
| Thick gloves |
| Tinted safety goggles |
| A fire extinguisher (at least 2 kg dry powder) |
| A fire blanket |
82
Ťažká
How do you make sure it is safe to light the torch for desoldering joints in a system from which a flammable refrigerant has been removed?
| Working outdoors is sufficient |
| Ensure good ventilation and check the work area with a flammable gas detector |
| Such joints must never be desoldered; they must be cut with a pipe cutter |
| Purge the system with compressed air |
83
Ťažká
How would you prepare a system containing 100 g of R1270 for debrazing, if local regulations allow controlled venting of small HC quantities?
| Vent the R1270 outdoors and start brazing immediately |
| Recover the R1270 to a vacuum and start brazing immediately without a nitrogen purge |
| Vent the R1270 to a safe outdoor location, then purge with OFN three times (pressurise and vent), and braze with OFN flowing |
| Vent the R1270 into the room and open a window |
84
Ťažká
Which method should NOT be used to locate an R290 leak?
| Fluorescent dye and UV lamp (if approved by the manufacturer) |
| An electronic detector for flammable refrigerants |
| An electronic leak detector designed for HFCs |
| Leak detection foam |
85
Ťažká
Why can’t recovery stations designed for HFCs be used with R600a?
| They contain ignition sources |
| The oil in the recovery unit is not soluble in R600a |
| The recovery unit cannot withstand the working pressure of R600a |
| 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 R1234ze(E) charge in a cold room measuring 5 m × 3 m × 2.5 m (LFL = 0.303 kg/m³, access category a, location class I, no additional measures)?
| 6.18 kg |
| 618 kg |
| 227 kg |
| 2.27 kg |
87
Ťažká
What type of refrigerant is R32?
| Hydrocarbon |
| Hydrofluoroolefin |
| Hydrofluorocarbon |
| Carbon dioxide |
88
Ťažká
What hazards do A2L refrigerants pose?
| Lower toxicity, higher flammability |
| Higher toxicity, higher flammability |
| Lower toxicity, lower flammability (burning velocity ≤ 10 cm/s) |
| Higher toxicity, lower flammability |
89
Ťažká
What hazard is associated with the combustion of HFO or HFC refrigerants?
| Nitrous oxide is formed |
| Phosgene is formed |
| Ozone is formed |
| Hydrogen fluoride (HF) is formed |
90
Stredne ťažká
What is the greenhouse effect?
| The filtering of solar radiation by the atmosphere |
| The formation of a layer that traps only heat from fuel combustion in aircraft |
| The trapping of heat in the Earth's atmosphere, which hinders the radiation of heat into space |
| The absorption of solar radiation by the Earth's surface |
91
Ťažká
Approximately what compressor displacement is required for R600a compared with R134a for the same cooling capacity?
| About twice as large |
| The same |
| About seven times as large |
| About half |
92
Ťažká
What is the GWP value for R32 according to Regulation (EU) 2024/573?
| 3 |
| 675 |
| 7 |
| 0 |
93
Ťažká
Why is charge accuracy more important in critically charged R290 systems than in HFC systems?
| The charge mass is much smaller than in an HFC system, because the liquid density of R290 is much lower |
| Because R290 is only used in systems below 150 g |
| Because such systems never have liquid receivers |
| Because of lower operating pressures |
94
Ťažká
Why does the condenser fan run continuously in some systems using R1270?
| To reduce energy consumption |
| To ensure that the discharge pressure never becomes excessive |
| To prevent the build-up of contaminants in the condenser |
| To dilute the refrigerant in the event of a leak |
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?
| Directive 2009/125/EC |
| Regulation (EU) No 517/2014 |
| Regulation (EU) 2015/1188 |
| Regulation (EU) 2024/573 |
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 ecodesign obligations of manufacturers of refrigerating appliances?
| Meeting implementing regulations (e.g. 2019/2019, 2015/1095): efficiency, spare parts, reparability |
| Only declaring F-gas quantities under Regulation (EU) No 517/2014 |
| Only implementing an ISO 9001 quality management system |
| Only using energy labels under Regulation (EU) 2024/573 |
98
Stredne ťažká
What is the main objective of EU ecodesign legislation (Directive 2009/125/EC, now Regulation (EU) 2024/1781 – ESPR)?
| To facilitate imports from outside the EU |
| To reduce the negative environmental impact of products by improving energy efficiency, durability and recyclability |
| To standardise the appearance of products in the EU |
| To increase sales of electrical appliances in the EU |
99
Stredne ťažká
What is the function of a ball valve in a refrigeration system?
| It prevents excessive pressure build-up in the system |
| It measures the moisture content of the refrigerant |
| It regulates the temperature of the refrigerant |
| Enables the refrigerant flow to be completely shut off |
100
Ľahká
What is the main function of a safety valve?
| Discharges refrigerant when the set pressure is exceeded |
| Prevents the evaporator from freezing |
| It controls the oil level in the compressor |
| It monitors the moisture content of the refrigerant |
101
Stredne ťažká
How do certain gases contribute to the greenhouse effect?
| They trap thermal radiation that the Earth would otherwise emit into space |
| They heat the air through chemical reactions with atmospheric oxygen and nitrogen |
| They limit UV radiation reaching the Earth's surface, changing the heat balance |
| They deplete the ozone layer, so more solar radiation reaches the surface |
102
Stredne ťažká
What is the purpose of a sight glass (with moisture indicator)?
| Visual assessment of the refrigerant condition in the liquid line (bubbles) and of system moisture |
| Emergency shut-off of flow |
| Regulating compressor pressure |
| Measuring condenser temperature |
103
Stredne ťažká
What is the function of the temperature regulator in a refrigeration system?
| It drains excess refrigerant into the receiver |
| It restricts oil flow |
| Controls the operation of the compressor and valves to maintain the set temperature |
| To maintain a constant pressure in the compressor |
104
Ťažká
What is the role of a suction liquid separator (also in systems with flammable or toxic refrigerants)?
| It prevents liquid refrigerant from entering the compressor |
| It separates liquid from oil |
| It is used only to measure moisture |
| It heats the refrigerant before the evaporator |
105
Ťažká
What is the function of an oil separator in systems using flammable or toxic refrigerants?
| Heats the refrigerant before it enters the evaporator |
| It prevents liquid from entering the compressor |
| 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 |
106
Stredne ťažká
What is the purpose of oil level regulators in a refrigeration system?
| They control the pressure in the condenser |
| They control the evaporator temperature |
| Maintains the correct oil level in the compressor |
| They drain off excess refrigerant |
107
Stredne ťažká
What is the function of the liquid receiver in relation to system tightness?
| It keeps the whole system at constant pressure regardless of load |
| It controls the evaporating temperature by varying the circulating charge |
| It stores refrigerant; checking its liquid level helps detect charge loss |
| It regulates the oil returning to the compressor |
108
Stredne ťažká
What is the role of a gauge manifold with thermometers (temperature probes)?
| It relieves pressure if it is exceeded |
| It monitors refrigerant moisture content |
| It controls oil level |
| It measures pressures and temperatures to determine superheat and subcooling and thus assess the system charge (indirect leak check) |
109
Stredne ťažká
What is the role of defrost controls?
| They protect the evaporator from icing and damage that could lead to leaks |
| They drain excess oil from the evaporator to the receiver |
| They monitor the moisture content of the refrigerant |
| They control compressor discharge pressure during defrost |
110
Ťažká
Why do liquid and oil separators in CO₂ systems require particular attention?
| Because of very high pressures – adequate PS and protection devices are required |
| Because CO₂ is flammable and separators must not be used |
| Because sight glasses and level indicators must not be used in CO₂ systems |
| Because CO₂ needs no lubrication, so oil separators are unnecessary |
111
Ťažká
What is the critical pressure of CO₂ (R744)?
| Approx. 10 bar |
| Approx. 74 bar (abs) |
| Approx. 120 bar |
| Approx. 31 bar |
112
Ľahká
What is the unit of pressure in the International System of Units (SI)?
| Pa (pascal) |
| atm (standard atmosphere) |
| bar (gauge) |
| psi (pound per square inch) |
113
Stredne ťažká
Where can the lists of fluorinated greenhouse gases be found?
| In a regulation of the Minister of Economy on the list of fluorinated greenhouse gases |
| In the Vienna Convention for the Protection of the Ozone Layer |
| In Annexes I–III to Regulation (EU) 2024/573 of the European Parliament and of the Council |
| In the national Act on ozone-depleting substances and certain fluorinated greenhouse gases |
114
Ťažká
What characterises the transcritical process in CO₂ systems?
| Conventional condensation occurs |
| It is irrelevant to system operation |
| Heat rejection takes place above the critical point – the refrigerant does not condense in the conventional way (gas cooler instead of condenser) |
| It occurs only at low temperatures |
115
Ťažká
What characterises the subcritical CO₂ process?
| The conventional condensation process below the critical point |
| Operation above the critical point |
| The absence of condensation |
| The absence of evaporation |
116
Ľahká
What is the log(p)-h diagram for CO₂ used for?
| For analysing thermodynamic processes in a refrigeration system |
| To measure temperature |
| To detect leaks |
| To regulate pressure |
117
Ľahká
What can be read from the log(p)-h graph?
| Only the humidity |
| Pressure, enthalpy, temperature and state of the refrigerant |
| Only the amount of refrigerant |
| Only the temperature |
118
Ľahká
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 |
119
Ľahká
What does the CO₂ saturation state mean?
| Dry ice state |
| Equilibrium between the liquid and vapour phases |
| A state of high pressure |
| A state in which the refrigerant is only a gas |
120
Ťažká
When can dry ice (solid CO₂) form?
| At high pressure |
| At high temperature |
| When the pressure drops suddenly below the triple point (approx. 5.2 bar abs, −56.6 °C), e.g. when venting liquid CO₂ or charging liquid into an evacuated system |
| During normal operation of the system |
121
Ťažká
What risks are associated with dry ice forming in a CO₂ system?
| No risk |
| Improved efficiency |
| Pressure reduction |
| Blocked pipes and valves and system damage (and a sharp pressure rise when it thaws) |
122
Ťažká
How does CO₂ saturation pressure change as temperature increases?
| It decreases |
| It remains the same |
| It increases rapidly |
| It first decreases, then increases |
123
Ľahká
Why is understanding the log(p)-h graph particularly important for CO₂?
| It is only used for design purposes |
| As CO₂ systems operate in different modes (sub- and transcritical) and require detailed analysis |
| It doesn’t matter |
| It only applies to NH₃ |
124
Stredne ťažká
Where can the lists of ozone-depleting substances be found?
| In the national Act on ozone-depleting substances and certain fluorinated greenhouse gases |
| In the Vienna Convention for the Protection of the Ozone Layer |
| In Annexes I and II to Regulation (EU) 2024/590 of the European Parliament and of the Council |
| In a regulation of the Minister of the Environment on the list of controlled substances |
125
Ťažká
What happens to CO₂ above the critical point?
| It ceases to conduct heat |
| It turns into a liquid |
| It transitions to a supercritical state (no distinction between liquid and gas) |
| It turns into a solid |
126
Ľahká
Why do CO₂ systems require precise pressure control?
| Because there are no valves |
| They do not require control |
| Due to low pressures |
| Due to significant pressure changes with temperature fluctuations |
127
Stredne ťažká
Why is ammonia (R717) classed as a toxic refrigerant?
| It severely irritates the respiratory tract, eyes and skin, and is poisonous when inhaled at higher concentrations |
| Because it is colourless and odourless and therefore hard to detect |
| Because it is heavier than air and displaces oxygen |
| Because it does not react with water, making neutralisation difficult |
128
Ťažká
What is the main difference between a dry-expansion and a flooded evaporator?
| In a dry-expansion evaporator the refrigerant completely evaporates and is superheated in the evaporator; in a flooded one part of the refrigerant remains liquid (incomplete evaporation, no superheat) |
| A dry-expansion evaporator needs no expansion valve, a flooded one does |
| A dry-expansion evaporator is filled with liquid, a flooded one with vapour |
| A dry-expansion evaporator always has a lower pressure than a flooded one |
129
Ťažká
What is the typical pressure in the evaporator of an R717 deep-freeze system (below −40 °C)?
| Below atmospheric (approx. 0.7 bar abs at −40 °C) |
| Positive pressure of 5–10 bar |
| Positive pressure of 10–20 bar |
| Atmospheric pressure, approx. 1 bar abs |
130
Ťažká
Why are PFAS formed by the decomposition of certain F-gases (e.g. TFA from HFOs) problematic?
| They are readily biodegradable |
| They are climate- and environment-neutral |
| They are very persistent, accumulate in the environment (e.g. water) and may be toxic |
| They cause rapid cooling of the atmosphere |
131
Ľahká
What is the basic requirement when charging a system with R717 (NH₃)?
| Charging can be carried out without personal protective equipment |
| Charging should take place in a well-ventilated area using appropriate personal protective equipment |
| NH₃ can be charged together with air |
| Charging must only take place at temperatures below 0°C |
132
Ťažká
How is oil managed in R717 systems?
| Oil requires no monitoring |
| Oil collecting at the lowest points of vessels is regularly checked and drained, because it impairs heat transfer |
| Oil has no effect on system operation |
| Oil can be mixed with any refrigerant |
133
Ľahká
What is the correct procedure for recovering R717 from a system?
| The gas can be released into the atmosphere |
| The refrigerant must be recovered into suitable, leak-proof tanks designed for NH₃ |
| Recovery is not required |
| The refrigerant can be drained into the sewer system |
134
Ľahká
How should R717 (NH₃) be stored?
| In sealed, labelled containers, in a cool and well-ventilated place |
| Near heat sources |
| In unmarked plastic containers |
| In any open containers |
135
Stredne ťažká
Where and by when must entities obliged under the Polish Act of 15 May 2015 submit annual reports on ODS and F-gases?
| By the end of the calendar year, on a form at a regional office of the Office of Technical Inspection (UDT) |
| By 31 March, electronically to the Ministry of Climate and Environment |
| By 31 January, in the Central Register of Operators (CRO) |
| By 28 February of the following year, electronically via the Reports Database (BDS) run at the Institute of Industrial Chemistry (ICHP) |
136
Ťažká
What should be done with contaminated R717?
| Continue to use it without restriction |
| Release it into the atmosphere |
| Dilute it with water and reuse it |
| Purify it or send it for disposal in accordance with regulations |
137
Ľahká
What is the main hazard associated with an R717 leak during maintenance work?
| Increased cooling efficiency |
| Damage to electrical equipment only |
| No risk whatsoever |
| Toxic to humans and may cause chemical burns |
138
Ťažká
What should be done if an NH₃ leak is detected?
| Increase the pressure in the system |
| Carry on working with the room door open |
| Evacuate people immediately and raise the alarm; stop the leak only if it is safe to do so and with suitable PPE (respiratory protection) |
| Carry on working wearing a dust mask |
139
Ťažká
What role do scrubbers play in NH₃ systems?
| They are used to measure temperature |
| Neutralise ammonia through absorption in a liquid (e.g. water) |
| They increase the pressure in the system |
| They store the refrigerant |
140
Ťažká
How should the system be prepared before filling with R717?
| Simply start it up |
| The pressure must be increased above the standard level |
| There is no need to check it |
| Check for leaks, remove air and moisture, and create a vacuum |
141
Ťažká
What are the transport requirements for R717?
| It must be carried in suitable, labelled packagings in accordance with ADR (UN 1005, class 2, code 2TC) |
| It can be carried in open containers |
| It can be carried without labelling |
| Transport is not regulated |
142
Ľahká
What personal protective equipment is required when working with NH₃?
| Only a safety helmet |
| Safety goggles, gloves and respiratory protective equipment |
| Workwear only |
| No requirements |
143
Stredne ťažká
Which installation measure has a major impact on compressor energy efficiency?
| Installing a suction line smaller than recommended |
| Proper evacuation and dehydration of the system (removing air and moisture) |
| Charging extra refrigerant 'as a reserve' above the nameplate value |
| Omitting the filter-drier to reduce flow resistance |
144
Stredne ťažká
How does regular oil-level monitoring affect compressor operation?
| It ensures proper lubrication and limits wear and energy losses |
| It allows any type of oil to be topped up |
| It allows the crankcase heater to be omitted |
| It increases cooling capacity above nominal |
145
Ľahká
How do system leaks affect compressor energy efficiency?
| They improve efficiency because condensing pressure drops |
| They affect only safety, not energy use |
| No effect as long as the system still cools |
| Refrigerant loss reduces capacity and increases energy use (longer run times, higher superheat) |
146
Stredne ťažká
Regulation (EU) 2024/590 relates to:
| Alternative refrigerants replacing fluorinated greenhouse gases |
| Conditions for F-gas certification of companies recovering and reclaiming refrigerants |
| Health and safety during refrigerant recovery |
| Ozone-depleting substances |
147
Stredne ťažká
What is the significance of proper suction and discharge pressure control?
| Pressures do not affect energy use |
| The lowest possible suction pressure is best |
| It keeps the compressor at optimal conditions (suction pressure as high and condensing pressure as low as permissible) |
| The highest possible condensing pressure is best |
148
Stredne ťažká
Which maintenance measure reduces compressor energy consumption?
| Topping up refrigerant at every service visit |
| Raising the high-pressure switch setting |
| Permanently disabling the crankcase heater |
| Replacing the filter-drier when the pressure drop or moisture indicator shows it is necessary |
149
Stredne ťažká
How does air (non-condensable gas) in the system affect operation?
| It lowers the condensing pressure |
| It improves condenser heat transfer |
| It only affects the sight-glass indication |
| It raises the condensing pressure and reduces efficiency |
150
Stredne ťažká
What role do controls play in compressor efficiency?
| They increase the circulating refrigerant charge |
| They matter only in NH₃ systems |
| They provide safety only, with no energy effect |
| They enable optimised operation and lower energy use (e.g. floating head pressure, capacity matching) |
151
Stredne ťažká
How does suction superheat at the compressor affect efficiency?
| Superheat has no effect |
| Zero suction superheat is optimal |
| Excessive superheat reduces efficiency and raises the discharge temperature |
| The higher the superheat, the higher the efficiency |
152
Stredne ťažká
How does correct system layout affect efficiency?
| It shortens pipe runs and limits pressure drops and energy losses |
| It affects only appearance |
| It doesn't matter |
| Longer pipes improve subcooling and always increase efficiency |
153
Stredne ťažká
How important is suction pipe insulation?
| It has no effect |
| It increases energy consumption |
| It limits heat gain and excessive superheat, improving efficiency |
| It is needed only for appearance |
154
Stredne ťažká
Which measure most improves condenser energy efficiency?
| Reducing fan speed to the minimum |
| Raising the condensing pressure set point |
| Increasing the refrigerant charge |
| Regular cleaning of heat-exchange surfaces |
155
Ľahká
How does a dirty condenser affect the operation of the refrigeration system?
| It improves efficiency |
| Causes an increase in pressure and energy consumption by the compressor |
| It has no effect |
| It lowers the condensing pressure |
156
Ľahká
Why is adequate airflow through an air-cooled condenser important?
| It ensures effective heat rejection and low condensing pressure |
| It affects only noise |
| It doesn't matter |
| The lower the airflow, the lower the condensing pressure |
157
Stredne ťažká
Which refrigerants damage the ozone layer?
| All refrigerants containing chlorine or bromine in their molecules |
| All refrigerants containing fluorine and hydrogen in their molecules |
| All natural refrigerants |
| All refrigerants containing carbon in their molecules |
158
Ľahká
How does the presence of limescale in a water-cooled condenser affect performance?
| It has no effect |
| It improves heat transfer |
| Impairs heat exchange and increases energy consumption |
| It lowers the condensation temperature |
159
Stredne ťažká
How does correct condensing pressure control affect efficiency?
| It is best to keep a constant high condensing pressure all year |
| It always increases energy use |
| It keeps the lowest pressure that still ensures proper expansion-valve feed, reducing energy use |
| It has no effect |
160
Ľahká
How do condenser leaks affect energy efficiency?
| Causes refrigerant loss and a drop in efficiency |
| They improve efficiency |
| They lower the temperature |
| Have no effect |
161
Ľahká
How important is the correct positioning of an air-cooled condenser?
| It should be installed in a well-ventilated area with unobstructed airflow |
| It doesn’t matter |
| It should be housed in a small room |
| It should be close to heat sources |
162
Ľahká
How does hot air recirculation affect the condenser?
| It has no effect |
| It improves efficiency |
| It reduces the pressure |
| Impairs cooling and increases energy consumption |
163
Stredne ťažká
How does insulation of heating and DHW pipework affect the efficiency of a heat pump system?
| It increases pressure |
| It doesn't matter |
| It impairs cooling |
| It reduces energy losses and improves overall system efficiency |
164
Stredne ťažká
Which measure most improves the energy efficiency of an air-cooling evaporator?
| Raising the condensing temperature by a few kelvin |
| Increasing the refrigerant charge above nominal |
| Defrosting at the right time and keeping the fins clean |
| Restricting the airflow through the evaporator |
165
Ľahká
How does evaporator icing affect the system’s operation?
| It lowers the condensation temperature |
| It improves cooling performance |
| Impairs heat exchange and increases energy consumption |
| It has no effect |
166
Ľahká
How does dirt on the evaporator surface affect its performance?
| It reduces the pressure |
| It has no effect |
| It improves efficiency |
| Impairs heat exchange and increases energy consumption |
167
Ľahká
What maintenance task is crucial for the evaporator?
| Regular cleaning and defrosting |
| Reduced airflow |
| Lack of maintenance |
| Increasing the refrigerant charge |
168
Stredne ťažká
What does a Certificate A2 for natural persons (Implementing Regulation (EU) 2024/2215) authorise?
| All activities (leak checks, installation, repair, maintenance, servicing, decommissioning, recovery) involving F-gases and hydrocarbons in equipment containing less than 3 kg, or less than 6 kg in labelled hermetically sealed systems |
| Only recovery of F-gases from equipment containing less than 3 kg (or 6 kg in hermetically sealed systems) |
| All activities involving equipment using CO₂ (R744) |
| Only leak checks that do not entail breaking into the refrigerant circuit |
169
Ľahká
How does superheat at the evaporator outlet affect efficiency?
| It always improves performance |
| It only causes a temperature drop |
| Excessive superheat reduces energy efficiency |
| It has no effect |
170
Ľahká
How do leaks in the evaporator affect efficiency?
| Increase capacity |
| These cause refrigerant loss and a drop in efficiency |
| Improves performance |
| Have no effect |
171
Ľahká
How important is correct expansion valve adjustment?
| It doesn’t matter |
| Causes leaks |
| Ensures optimal evaporator charge and improves efficiency |
| It increases energy consumption |
172
Ľahká
How does inadequate insulation of suction (or secondary-coolant) pipes affect evaporator performance?
| It lowers the condensing temperature |
| It improves efficiency |
| It has no effect |
| It causes cooling losses and increased energy use |
173
Ľahká
How does correct TEV adjustment affect system energy efficiency?
| It ensures optimal superheat and improves efficiency |
| It causes leaks |
| It increases energy use |
| It has no effect |
174
Ľahká
What happens if the superheat set by the TEV is too high?
| Efficiency will drop because the evaporator is not being fully utilised |
| The refrigerant charge will increase |
| It has no effect |
| Cooling efficiency will improve |
175
Stredne ťažká
How does too low superheat setting on the TEV affect performance?
| It increases operational safety |
| It has no effect |
| It reduces refrigerant flow |
| It may lead to improved efficiency, but it increases the risk of the compressor becoming flooded with liquid |
176
Ľahká
How do contaminants in the system affect the operation of the TEV?
| They can cause it to become blocked and reduce efficiency |
| Have no effect |
| They improve its performance |
| They lower the temperature |
177
Ľahká
What role does the filter-drier play in terms of system efficiency?
| It increases the amount of refrigerant |
| It doesn’t matter |
| Removes moisture and contaminants, improving the system’s efficiency |
| It lowers the temperature |
178
Ľahká
How does proper insulation of components (e.g. pipes near the TEV) affect the system?
| It doesn’t matter |
| It causes leaks |
| It increases energy consumption |
| Prevents unwanted heat gains and improves efficiency |
179
Stredne ťažká
What is the scope of Regulation (EU) 2024/573?
| Design requirements and conformity assessment for pressure equipment |
| Limiting emissions, use and marketing of F-gases, HFC phase-down, certification and reporting |
| Only requirements for periodic leak checks of refrigeration equipment |
| Health and safety requirements for brazing and welding on refrigeration installations |
180
Ľahká
How important is it to check the operation of the condensing pressure control valve in the system?
| Ensures operation within the optimum pressure range and reduces energy losses |
| It has no effect |
| It increases energy consumption |
| It causes a significant rise in temperature |
181
Ľahká
How does the correct selection of a TEV affect energy efficiency?
| It doesn’t matter |
| It lowers the temperature |
| Ensures the system is matched to its capacity and operates optimally |
| It increases the amount of refrigerant |
182
Stredne ťažká
What is the main design difference in hydrocarbon refrigeration systems?
| No need for safety measures |
| Lower energy efficiency |
| The need to eliminate ignition sources and limit the charge because of the refrigerant's flammability |
| Higher operating pressures |
183
Stredne ťažká
How do compressors used in hydrocarbon systems differ?
| They must be approved by the manufacturer for the specific flammable refrigerant (e.g. electrical components that are not ignition sources, suitable oil) |
| There is no difference |
| They must operate at higher pressures than HFC compressors |
| They need no lubrication |
184
Ťažká
What is the main characteristic of R744 (CO₂) refrigeration systems?
| Low operating pressures |
| Very high operating pressures |
| No need for control |
| Low energy efficiency under all conditions |
185
Ťažká
What are the requirements for piping materials in CO₂ systems?
| Any material may be used |
| They must withstand high pressures (e.g. stainless steel, high-strength copper-alloy tubes such as K65) |
| It doesn't matter |
| Only plastics |
186
Ťažká
How does a booster system work in CO₂ installations?
| It reduces the refrigerant quantity |
| It is used to store refrigerant |
| It reduces evaporator pressure |
| Low-temperature (LT) compressors discharge into the suction of medium-temperature (MT) compressors – two-stage compression in a single circuit |
187
Ľahká
What is the function of high-pressure control valves in CO₂ systems?
| They lower the evaporator temperature |
| They are used to store the refrigerant |
| They regulate oil flow |
| They control the pressure on the high-pressure side and optimise system operation |
188
Ťažká
Why is pressure optimisation in CO₂ systems crucial?
| It reduces the ambient temperature |
| It doesn’t matter |
| It reduces the amount of refrigerant |
| It enables the system to achieve maximum energy efficiency in transcritical mode |
189
Ťažká
What role does parallel compression play in CO₂ systems?
| It compresses flash gas from the intermediate receiver directly to high pressure, improving efficiency |
| It lowers the ambient temperature |
| It increases energy consumption |
| It has no significance |
190
Stredne ťažká
How can you tell that the system has been overcharged with refrigerant?
| It cannot be checked, because the sight glass is not intended for this |
| Even under a very small heat load, frost forms on the suction line |
| Under normal operating conditions the condensing pressure and subcooling rise markedly because excess liquid floods the condenser and reduces its active surface |
| The compressor runs at a lower load and the suction pressure drops |
191
Ťažká
How does an ejector work in a CO₂ system?
| Stores the refrigerant |
| It increases the amount of refrigerant |
| 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 |
192
Ťažká
What is the function of liquid ejectors in CO₂ systems?
| They return liquid from the separator and allow partially flooded evaporator operation (better evaporator feed) |
| They reduce atmospheric pressure |
| They raise the refrigerant temperature |
| They increase the amount of oil |
193
Ťažká
What are the characteristics of partially flooded systems in CO₂ systems?
| The absence of liquid in the evaporator |
| The presence of liquid in the evaporator, which improves heat transfer and efficiency |
| Low operating pressure |
| Lack of regulation |
194
Ťažká
What is the main risk associated with standstill pressure in CO₂ systems?
| A drop in temperature |
| A decrease in refrigerant quantity |
| A pressure rise as the refrigerant warms up during standstill (possibly exceeding PS and lifting the relief valves) |
| Increased efficiency |
195
Ťažká
How is standstill pressure limited in CO₂ systems?
| By increasing the refrigerant charge |
| By completely shutting down the system and power supply |
| By using an auxiliary standstill (stagnation) cooling unit, e.g. cooling the receiver, with back-up power, and by selecting an adequate PS and relief valves |
| By raising the plant-room temperature |
196
Ťažká
What does standstill (stagnation) of a CO₂ system mean, and why is it important?
| Improved efficiency |
| A state with no compressor operation or refrigerant flow – pressure rises with ambient temperature and may exceed PS |
| Normal system operation |
| A drop in system temperature |
197
Ľahká
Why do CO₂ systems require more advanced automation than traditional systems?
| Because there are no valves |
| Due to the need for precise control of pressure and temperature |
| Due to low pressures |
| They do not require automation |
198
Ťažká
What must the label of a flammable refrigerant cylinder include?
| The refrigerant name, the UN number, the hazard label (e.g. 2.1 – flammable gas) and basic safety information |
| Only the refrigerant name |
| Information about the cylinder owner |
| Only the net weight |
199
Ťažká
Why is the absence of a 'flammable refrigerant' label on equipment a serious hazard?
| It may lead to the use of tools that are ignition sources |
| It reduces system efficiency |
| It may lead to the wrong oil being selected |
| It has no significant effect on safety |
200
Ťažká
Which set of information on the label of a flammable refrigerant cylinder is crucial from a safety perspective?
| Name of the substance, hazard label (ADR) / GHS pictogram (CLP), UN number |
| Gross weight and batch number |
| Manufacturer’s name and country of origin |
| Cylinder colour and date of manufacture |
201
Stredne ťažká
Before charging the unit with refrigerant, it is essential to…
| …carry out a tightness test (and evacuate the system) |
| …carry out a trial start-up |
| …check the compressor suction and discharge connections |
| …fill in the unit's data sheet |
202
Ľahká
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 |
203
Ľahká
What are the potential consequences of using unsuitable connections in a system containing a flammable substance?
| Risk of leakage and the formation of an explosive mixture |
| No impact on safety |
| Merely a reduction in efficiency |
| Merely installation difficulties |
204
Ťažká
What is the purpose of gas detectors in a room with a refrigeration system?
| Monitoring pipe pressure |
| Early leak detection and triggering of measures preventing health risks and explosive atmospheres (alarm, ventilation, shut-off) |
| Controlling compressor capacity |
| Measuring refrigerant temperature |
205
Ťažká
How often should gas detection sensors in a machinery room be checked?
| Once every 5 years |
| Before every start-up of the unit |
| Only after a leak has occurred |
| According to the manufacturer's instructions and regulations – at least every 12 months |
206
Ťažká
Where should a gas detector be located according to EN 378?
| Anywhere in the room |
| Only at the room entrance |
| Near the control panel |
| Where the refrigerant would accumulate: low (near the floor) for refrigerants heavier than air, high (near the ceiling) for lighter ones such as NH₃ |
207
Ľahká
How should an employee respond when a gas alarm is triggered?
| Reduce the pressure in the system |
| 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 |
208
Ťažká
What safety checks should be carried out when installing a new refrigeration system with a flammable refrigerant?
| The colour of pipes and hoses |
| The presence of health and safety signage, adequate ventilation and gas detectors |
| Only that the air filter is new |
| Only the compressor power |
209
Ľahká
Gas detectors should be installed in rooms where:
| Ventilation is natural |
| The amount of refrigerant exceeds a specified permissible threshold |
| The room is less than 5 m² |
| Any refrigerant is present, regardless of the quantity |
210
Ťažká
What are the requirements for emergency exits from a refrigeration machinery room?
| Outward-opening doors and signed escape routes (number of exits per the standard) |
| In small machinery rooms emergency exits need not be signed |
| At least two exits are required and signage is optional |
| One exit with a sign stating the refrigerant type is sufficient |
211
Ťažká
Which installation measure for a flammable-refrigerant system improves its energy efficiency?
| A thorough tightness test and evacuation (dehydration) of the system |
| Restricting room ventilation |
| Charging above the nameplate quantity |
| Omitting the filter-drier |
212
Stredne ťažká
What information must appear on the label of equipment containing F-gases?
| Only the trade name of the refrigerant and the unit's serial number |
| The weight and capacity of the pipework and the colour code of the casing paint |
| That it contains an F-gas, its designation, quantity in kg and t CO₂ eq, and GWP |
| The manufacturer's logo, the unit weight and year of manufacture from the rating plate |
213
Ľahká
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 refrigerant charge in HC systems?
| It increases capacity |
| It lowers the temperature |
| It limits the possibility of reaching a flammable concentration (≥ LFL) in a leak, increasing safety |
| It doesn't matter |
215
Ľahká
Why is the cleanliness of heat exchangers in HC systems important?
| It doesn’t matter |
| It improves heat transfer and reduces energy consumption |
| It increases the pressure |
| Causes leaks |
216
Ľahká
What maintenance measures improve the efficiency of a system using a flammable refrigerant?
| Regular checks for leaks and operating parameters |
| Lack of servicing |
| Increasing the refrigerant charge |
| Disabling safety devices |
217
Ľahká
How does the correct selection of components affect a system using a flammable refrigerant?
| It ensures safe and optimal operation and minimises energy losses |
| It lowers the temperature |
| It increases the amount of refrigerant |
| It doesn’t matter |
218
Ľahká
Why is it important to use the correct service tools in HC systems?
| Causes leaks |
| It doesn’t matter |
| It ensures operational safety and reduces refrigerant losses |
| It increases energy consumption |
219
Ľahká
How does pipe insulation affect the efficiency of systems containing HC?
| Causes leaks |
| It doesn’t matter |
| It reduces energy losses and improves efficiency |
| It increases the pressure |
220
Ťažká
Which safety class applies to R744?
| B2L |
| A2. |
| A3 |
| A1 |
221
Ťažká
In a simple single-stage R744 system without an intermediate receiver (refrigerant flows from the gas cooler directly to the expansion valve), operating transcritically at 90 bar with a gas-cooler outlet temperature of 35 °C, the refrigerant upstream of the expansion valve is…
| …a two-phase mixture at intermediate pressure |
| …a subcooled liquid |
| …saturated vapour at intermediate pressure |
| …a supercritical fluid |
222
Ťažká
In R744 transcritical 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 |
223
Ľahká
What is the base unit of temperature according to the International System of Units (Système International d’Unités)?
| K |
| °R |
| °F |
| °C |
224
Stredne ťažká
Which set of information best reflects the content of the equipment records required by Regulation (EU) 2024/573?
| Only the date of installation and the installer's name |
| Operator details, equipment details, type and quantity of refrigerant, and information on servicing and repairs |
| The make and model of the unit |
| The owner, installer and service technician of the unit |
225
Ťažká
Which statement best describes the behaviour of R717 and mineral compressor oil?
| An oil return line cannot be used in R717 systems because the oil is too hot |
| R717 mixes very well with the oil, which easily returns to the compressor |
| R717 does not mix with the oil; the oil, being heavier than liquid NH₃, collects beneath it at the lowest points (mainly on the low-pressure side) |
| R717 does not mix with the oil; the oil collects on the high-pressure side above the R717 |
226
Ťažká
What is the main reason for using K65 copper tubing in some R744 systems?
| They bend easily |
| They have good low-temperature performance |
| They come in a wider range of diameters |
| They can withstand higher pressures |
227
Ťažká
Which statement about installing Schrader valves is correct?
| Schrader valves must not be used in R744 systems |
| All Schrader cores are suitable for all refrigerants |
| Hydrocarbons leak through Schrader valves |
| When brazing the valve body, the core must be removed, then refitted and tightened to the correct torque |
228
Ťažká
Which refrigerant can be detected with phenolphthalein paper?
| R717 |
| R744 |
| R1234ze(E) |
| R1270 |
229
Ťažká
How does an undercharge affect the high-pressure side (without discharge pressure control)?
| Discharge pressure higher, subcooling higher |
| Discharge pressure lower, subcooling higher |
| Discharge (condensing) pressure and subcooling will both be lower |
| Discharge pressure higher, subcooling lower |
230
Ťažká
What is the benefit of adding helium as a tracer gas to nitrogen in a pressure test?
| It has a higher pressure than pure nitrogen in the same cylinder |
| It reacts with refrigerant residues, producing a visible colour change |
| Its small atoms pass easily through leaks and are detected |
| It has a distinctive odour that helps locate the leak |
231
Ťažká
Why should an evacuated R744 system initially be charged with refrigerant in the vapour phase?
| To prevent the drain valve on the receiver from opening |
| To prevent dry ice forming (until approx. 5.2 bar abs is exceeded) |
| To avoid damaging the compressor with liquid CO₂ |
| To charge R744 more slowly and measure it more accurately |
232
Ťažká
If moisture remains in an R744 system because it was not properly evacuated (dehydrated), what is the likely consequence?
| Formation of hydrogen fluoride and hydrofluoric acid |
| Reduced cooling capacity |
| Excessive discharge pressure |
| Formation of carbonic acid, which damages the system |
233
Ťažká
Which system may require manual oil recovery?
| Secondary system using R744 |
| Supercritical ‘booster’ system using R744 |
| An R717 system |
| R744 cascade system |
234
Ťažká
The pressure of R744 at a saturation temperature of 20 °C is approx.
| 14 bar g |
| 25 bar g |
| 90 bar g |
| 56 bar g |
235
Stredne ťažká
Who is responsible for keeping the equipment records?
| The person responsible for risk assessment. |
| The equipment maintenance technician. |
| There is no such obligation. |
| The operator of the unit or system. |
236
Ťažká
Which refrigerant is lighter than air?
| R1270 |
| R744 |
| R1234ze(E) |
| R717 |
237
Ťažká
What hazards are associated with a safety group A3 refrigerant?
| Lower toxicity, no flame propagation |
| Higher toxicity, no flame propagation |
| Higher flammability, lower toxicity |
| Lower flammability, lower toxicity |
238
Ťažká
What is the GWP of R32 (per AR4, as used in Regulation (EU) 2024/573)?
| 3922 |
| 675 |
| 0 |
| 6 |
239
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, height of the indoor unit, floor area |
| Lower flammability limit, room volume |
| Practical limit, height of the indoor unit, floor area |
240
Ťažká
What compressor displacement is required for R1270 compared with an R404A compressor in the medium-temperature range (cold room)?
| About 6 times larger |
| About 1.5 times larger |
| Similar |
| About half |
241
Ťažká
At an ambient temperature of 25 °C, the standstill pressure in the low-pressure stage of an R744 cascade (without standstill cooling) will typically be…
| …approx. 27.5 bar g |
| …higher than the maximum allowable pressure (PS) of the low-pressure stage |
| …the same as the high-pressure switch setting |
| …the same as the relief valve set pressure |
242
Ťažká
What is the correct definition of critical temperature?
| 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 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 |
243
Ťažká
In the gas cooler of a transcritical system, the supercritical working fluid…
| …rejects heat at constant temperature and pressure |
| …rejects heat as its pressure falls |
| …rejects heat during a phase change |
| …rejects heat as its temperature falls |
244
Ťažká
R717 is highly corrosive to:
| copper (and its alloys) |
| titanium |
| aluminium |
| stainless steel |
245
Ťažká
What can be the effect of a relief valve lifting repeatedly?
| The valve no longer opens |
| The set pressure increases |
| The valve stays fully open permanently |
| The valve may not reseat tightly and its set (opening) pressure may decrease |
246
Stredne ťažká
Where are oil traps installed on the suction line?
| Before the safety valve on the suction side |
| Immediately before the compressor suction connection |
| At the inlet to every component of the refrigeration system |
| At the bottom of vertical suction risers with upward flow |
247
Ťažká
What is the relationship between the pressure (p) and temperature (T) of nitrogen at the start (1) and end (2) of a tightness test (p absolute, T in kelvin)?
| p₂ = (p₁ × T₁)/T₂ |
| p₂ = T₂/(p₁ × T₁) |
| p₂ = (p₁ × T₂)/T₁ |
| p₂ = T₁/(p₁ × T₂) |
248
Ťažká
What is the recommended pre-alarm level for fixed leak detection systems for R717?
| 500 ppm |
| 5,000 ppm |
| 500,000 ppm |
| 50,000 ppm |
249
Ťažká
Why are compressors with a separate motor (open type) mostly used in R717 systems?
| Because NH₃ attacks copper motor windings, so hermetic compressors with conventional windings are not used |
| To increase the refrigerant charge |
| Because they are cheaper |
| To lower the condensing pressure |
250
Ťažká
Which type of compressor is most commonly used in large ammonia systems?
| Hermetic scroll |
| Diaphragm compressor |
| A reciprocating or screw compressor |
| Rotary vane compressor |
251
Ťažká
How is the capacity of a piston compressor regulated in NH₃ systems?
| Solely by adjusting the oil volume |
| By unloading the cylinders or changing the rotational speed |
| By increasing the condensing pressure |
| By reducing the refrigerant charge |
252
Ťažká
How is the capacity of a screw compressor most commonly controlled?
| By changing the type of oil |
| By adjusting the oil level |
| By closing the suction valve |
| By using a slide valve |
253
Ťažká
When is two-stage compression used in NH₃ systems?
| Only with water-cooled condensers |
| At small temperature differences |
| At low evaporating temperatures (pressures) and high pressure ratios |
| Only in small systems |
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 |
| Lower efficiency |
| Higher energy consumption |
255
Ťažká
How does an evaporative condenser used in NH₃ systems work?
| It transfers heat only to the air |
| It does not require a water supply |
| It utilises the evaporation of water to increase cooling efficiency |
| Operates without a fan |
256
Ťažká
What is the function of the liquid separator in an NH₃ system?
| Regulates the condensing pressure |
| It prevents liquid from entering the compressor |
| It separates oil from the refrigerant |
| Increases the discharge temperature |
257
Stredne ťažká
Which symptoms with the compressor running indicate a refrigerant leak (undercharge)?
| Low suction pressure, high superheat and negligible subcooling |
| Rising condensing and suction pressures with no superheat |
| Sight glass full of liquid and rising oil level in the crankcase |
| Rising liquid level in the receiver and increasing subcooling |
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 monitors the liquid level in the tank or separator |
| It is used to detect leaks |
| It controls the fan’s operation |
| It regulates the condensation temperature |
260
Ťažká
What is a thermosyphon in NH₃ systems?
| A system with gravity-driven (natural) circulation of liquid refrigerant caused by density differences, used e.g. for screw compressor oil cooling |
| An oil circulation pump |
| A defrosting device |
| A type of safety valve |
261
Ťažká
Why are oils that are immiscible with the refrigerant used in NH₃ systems?
| To increase the amount of refrigerant |
| Because NH₃ does not mix with most compressor oils |
| Because the oil mixes only with water |
| To reduce the pressure |
262
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 |
263
Ťažká
In which NH₃ system does the refrigerant evaporate completely with superheat in the evaporator, fed by an expansion valve?
| A direct-expansion (DX) system |
| A pumped liquid-recirculation system |
| A glycol system |
| An indirect system |
264
Ťažká
What is the characteristic feature of a flooded evaporator system?
| No level control is required |
| The evaporator is filled exclusively with vapour |
| The evaporator contains a large amount of liquid, which improves heat transfer |
| No separator is used |
265
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 |
266
Stredne ťažká
Which components of a refrigeration system are potential leak points subject to leak checks?
| Hermetic compressors, liquid receivers and liquid separators |
| Joints, valves (including stems), seals (including those on replaceable filters and driers), parts subject to vibration and connections to safety and measuring devices |
| Only high-pressure-side components |
| Only suction-side components |
267
Stredne ťažká
What pressure is used for the pressure tightness test of an installation?
| A pressure chosen by the technician based on experience |
| The pressure specified in EN 378-2 or by the manufacturer, not exceeding the maximum allowable pressure of the system (PS) |
| A pressure equal to the maximum pressure measured during operation |
| Always 30 bar |
268
Stredne ťažká
At which points of the unit must the leak check be carried out?
| At all points where there is a potential risk of refrigerant leakage |
| Only on compressor shut-off valves, solenoid valves and filters |
| Only at connections of measuring instruments |
| Only on discharge-side components |
269
Stredne ťažká
When can a unit be considered tight after a pressure test?
| When it has been checked with a fixed electronic detector |
| When the pressure drop does not exceed 0.1 bar regardless of the test duration |
| When gas bubbles appear after immersion in water |
| When the pressure remains constant during the test (allowing for temperature-related changes); any unexplained pressure drop requires the leak to be located |
270
Stredne ťažká
Which legal act currently sets out the obligation to check stationary refrigeration equipment containing F-gases for leaks, and how often this must be done?
| Implementing Regulation (EU) 2024/2215 |
| Commission Regulation (EC) No 1516/2007 |
| Regulation (EU) No 517/2014 |
| Regulation (EU) 2024/573 |
271
Ťažká
Which parts of a refrigeration system should be given particular attention during a leak check?
| Joints, valves incl. stems, seals, parts subject to vibration, connections to safety devices |
| Only compressor connections, because they are the only parts subject to vibration |
| Compressor and receiver connections, because the pressure is highest there |
| Only condenser connections, because the refrigerant is liquid there |
272
Ľahká
What is the superheat of refrigerant vapour?
| The amount of heat required to evaporate a liquid |
| The difference between the condensing temperature and the ambient temperature |
| The difference between the actual vapour temperature and the saturation temperature corresponding to its pressure (expressed in K) |
| The difference between the saturation temperature and the actual liquid temperature in the liquid line |
273
Ťažká
Leak checks can be carried out using various methods. Which pair is correct?
| Physical and chemical methods |
| Direct and indirect methods |
| Methods with and without quality control of supplies |
| Material quality control methods and electronic methods |
274
Ťažká
To whom can leak checks of stationary refrigeration equipment containing F-gases be entrusted?
| An employee appointed by the owner of the installation |
| Any leak-testing specialist |
| A person who has carried out such checks before |
| A natural person holding a certificate covering leak checks (A1, A2 within its charge limit, or E) |
275
Ťažká
What conditions must be met to use UV dye for leak checking?
| It is sufficient to have a UV lamp, dye and safety goggles |
| A UDT authorisation for pressure testing is required |
| It is sufficient that introducing dye into the circuit is technically feasible |
| Manufacturer approval of the method and a certificate covering breaking into the circuit |
276
Ťažká
Which leak-checking methods are considered direct methods?
| 1. gas detection devices (portable or fixed leak detection system), 2. UV detection fluid or dye, 3. bubble/foam solutions |
| Pressure-change measurement and immersion in water |
| Vacuum test and foam solution |
| Nitrogen with tracer gas and pressure measurement |
277
Ťažká
What do indirect leak-checking methods involve?
| Leak detection with an electronic detector |
| Ultrasonic measurement |
| A visual and manual check and analysis of parameters: pressure, temperature, compressor current, liquid levels and recharge volume |
| Leak detection with UV dye |
278
Stredne ťažká
How should the pressure be increased during a pressure tightness test?
| As quickly as possible |
| Gradually, in stages, checking for leaks at each level until the test pressure is reached |
| In any way |
| In one step, by fully opening the nitrogen cylinder valve |
279
Stredne ťažká
What electronic equipment should be used for leak checking?
| Detectors suited to the refrigerant in the system, with appropriate sensitivity, checked periodically |
| Only hot-cathode devices |
| Only detectors with an infrared sensor |
| Only devices with an 'ion pump' sensor |
280
Stredne ťažká
What documentation should be checked before starting a leak check?
| Only the installation invoice and the first start-up report |
| The operator's fixed-asset inventory ledger |
| Attendance sheets of the plant-room staff for the year |
| The equipment records – especially recurring problems and previous leaks |
281
Stredne ťažká
What information must be recorded in the leak check report?
| Date, number and location of leaks, how they were repaired, technician details and signature |
| Only the number of leaks found and the date of the check |
| The method used, the time spent on site and the cost of repair |
| The date, a general note about the leak and the operator's signature |
282
Stredne ťažká
What pressure should be used for the pressure tightness test?
| Always 10–12 bar |
| Any pressure, at the technician's discretion |
| Always 2–3 bar |
| A pressure not exceeding the maximum allowable pressure of the system (PS) |
283
Stredne ťažká
What is the temperature glide of a refrigerant?
| A property of single-component refrigerants, for which one saturation temperature corresponds to a given pressure |
| In zeotropic mixtures, the difference between the temperatures at the start and end of a phase change (boiling or condensation) at constant pressure |
| The temperature drop of the refrigerant across the expansion valve |
| The temperature rise of the vapour in the compressor |
284
Ťažká
What does a vacuum (decay) test involve?
| After isolating the pump, you check whether the system pressure rises |
| With the pump running, you watch the vacuum gauge reading |
| The pump runs continuously to hold the required vacuum for the test |
| The pump is restarted every time the system pressure 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)?
| Once every six months. |
| Only when servicing the unit. |
| On initial commissioning. |
| At least once every 12 months. |
286
Ťažká
How often should leak tests be carried out on equipment containing 7 kg of R404A refrigerant (27.45 tonnes of CO₂ equivalent)?
| At least once every 12 months. |
| On initial commissioning. |
| Once every six months. |
| Only when servicing the unit. |
287
Stredne ťažká
In which equipment is a leakage detection system required?
| Equipment with 50 t CO₂ eq or more of F-gases, regardless of equipment type |
| Equipment with ≥ 500 t CO₂ eq of Annex I F-gases (or ≥ 100 kg of Annex II Section 1 gases) |
| Equipment with 30 kg or more of F-gases, regardless of their GWP |
| Equipment with 5 t CO₂ eq or more of F-gases, regardless of equipment type |
288
Ťažká
Under Regulation (EU) 2024/573, a leakage detection system is mandatory when:
| the F-gas charge of the refrigeration equipment is 500 t CO₂ eq or more |
| the charge is 100 kg or more of ozone-depleting substances |
| the equipment contains a flammable refrigerant in any quantity |
| the equipment operates in an enclosed space |
289
Ťažká
Which leak-checking method may NOT be used by a holder of a Category E certificate?
| Measurement with a handheld electronic detector |
| Leak checking with a fluorescent dye introduced into the circuit |
| Visual inspection |
| Checking with a foaming solution |
290
Stredne ťažká
What should you check before using a portable electronic leak detector?
| That it has been zeroed close to the suspected leak point |
| That it has an infrared sensor, as only this type is permitted |
| That it holds a valid UDT inspection certificate |
| That it suits the refrigerant and has been checked as the manufacturer requires |
291
Stredne ťažká
Which certificate types (A1, A2, B, C, D, E) authorise leak checks of equipment containing F-gases?
| All except D |
| A1, A2 and E |
| Only A1 and A2 |
| Only E |
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?
| Between 24 hours and 1 month after the repair. |
| At the next periodic inspection. |
| Immediately after the repair. |
| At any time. |
293
Ťažká
How often must refrigeration equipment containing ≥500 t CO₂ eq of F-gases be checked if (contrary to Article 6) no leakage detection system is installed?
| Every 12 months |
| Every 3 months |
| Every 6 months |
| Every month |
294
Stredne ťažká
Why is it advisable to subcool the liquid refrigerant?
| To lower the evaporating temperature in the evaporator |
| To ensure that liquid free of vapour bubbles enters the expansion valve |
| To allow a smaller expansion valve to be used |
| To allow a condenser with a smaller heat-exchange surface to be used |
295
Stredne ťažká
What must be done after repairing a leak in the refrigeration unit of a refrigerated trailer?
| Update the equipment records and carry out a leak check (it may be done directly after repair) |
| Issue the invoice and leave the leak check to the next periodic service |
| Charge an alternative refrigerant, start up and measure the parameters |
| Visually inspect only the bolted and brazed joints near the repair |
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 from containers, products and equipment during maintenance or servicing or prior to their disposal. |
| The reuse of fluorinated greenhouse gases following a basic purification process. |
| The reprocessing of fluorinated greenhouse gases to achieve their specified standard properties. |
297
Stredne ťažká
Who is authorised to recover refrigerant from stationary refrigeration equipment containing F-gases?
| A natural person holding a certificate of the relevant type (A1; A2. or D within their charge limit) |
| The administrator of the operator's account in the register |
| The owner of the installation |
| The operator |
298
Stredne ťažká
How must recovered refrigerants be stored?
| In a labelled recovery cylinder with a dual valve and a valid inspection |
| In any used refrigerant cylinder, provided it is leak-tight |
| In any pressure vessel that has some form of approval |
| In a disposable (non-refillable) cylinder that held the same refrigerant |
299
Stredne ťažká
When should the recovery of fluorinated greenhouse gases be carried out:
| Before the final disposal of equipment and, where applicable, during its servicing and maintenance. |
| Before each leak test of the equipment. |
| Always during servicing and maintenance of equipment. |
| Only prior to the final disposal of equipment. |
300
Stredne ťažká
What should be done if recovered refrigerant is contaminated (e.g. with acid, air or moisture)?
| Clean the mixture yourself using a filter-drier |
| Hand it over to a specialised, authorised company for reclamation or destruction |
| Pass it through a particle filter and reuse it |
| Add a special contaminant neutraliser |
301
Stredne ťažká
What should be done if different refrigerants have been mixed in a storage cylinder?
| Separate the mixture into its components yourself |
| Pass it through a filter-drier and reuse it |
| Add a special refrigerant to the mixture |
| Hand the mixture over to an authorised company – as a rule for destruction |
302
Stredne ťažká
How does push-pull refrigerant recovery work?
| Nitrogen is injected into the system, pushing the refrigerant into the atmosphere |
| The recovery unit draws vapour from the recovery cylinder and pushes it into the system; the pressure difference forces liquid refrigerant out of the system into the cylinder |
| The recovery unit draws vapour from the system and condenses it in the cylinder |
| Refrigerant is drawn alternately from the suction and discharge sides of the compressor |
303
Stredne ťažká
What are the options for managing waste refrigerant?
| Recovery, disposal |
| Recycling, reclamation, destruction |
| Disposal, storage |
| Reclamation, recovery |
304
Stredne ťažká
Which management option restores recovered refrigerant to a quality equivalent to virgin product, so that it can be used by any undertaking?
| Reclamation |
| Destruction |
| Recycling |
| Storage |
305
Stredne ťažká
The lower the evaporating temperature, …
| …the greater the density of the suction vapour and the lower the refrigerant mass flow rate |
| …the lower the density of the suction vapour and the lower the refrigerant mass flow rate |
| …the greater the density of the suction vapour and the greater the refrigerant mass flow rate |
| …the lower the density of the suction vapour and the greater the cooling capacity of the compressor |
306
Stredne ťažká
How must transportable pressure vessels (e.g. refrigerant cylinders) be marked?
| Among other things: the number of the design and testing standard, marks of the approving country and the inspection body, the date of the initial inspection, and the manufacturer's and operational marks |
| Only with weight and capacity marks |
| The marking is optional |
| With the manufacturer's logo and date of manufacture |
307
Stredne ťažká
The recovery of refrigerants does not require the use of:
| A refrigerant recovery station. |
| Hoses with shut-off valves. |
| An electronic leak detector. |
| Scales with a measurement range suitable for the size of the cylinder being filled. |
308
Stredne ťažká
What functions does the compressor perform in a refrigeration system?
| The compressor compresses ambient air and increases the pressure of the refrigerant. |
| The compressor condenses the refrigerant. |
| The compressor creates a vacuum on the suction side of the system |
| 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 compression ratio of a compressor?
| The ratio of absolute discharge pressure to absolute suction pressure (pc/po) |
| The amount of refrigerant compressed per cycle relative to heat capacity |
| The ratio of suction pressure to discharge pressure (po/pc) |
| The ratio of discharge pressure to the effective capacity of the compressor (p/Vk) |
310
Stredne ťažká
What is compressor flooding (liquid slugging)?
| A large amount of liquid refrigerant in a flooded evaporator, which is a normal operating condition |
| Excess oil in the condenser |
| Flooding of the compressor by rainwater |
| Liquid refrigerant or oil entering the compression chamber |
311
Stredne ťažká
Within what range is the compressor motor speed typically controlled using a frequency inverter?
| Speed control does not change the cooling capacity |
| Approximately 30 to 75 Hz, corresponding to about 60–150% of nominal capacity (depending on the compressor manufacturer) |
| From approximately 10% to 90% of nominal capacity |
| By a maximum of 10% |
312
Ľahká
What is the theoretical displacement (swept volume flow) of a compressor?
| The volume of a single cylinder in cm³ |
| The volume of refrigerant flowing in one piston cycle under actual operating conditions |
| A value expressed by the coefficient of performance (COP) |
| The volume of vapour drawn in per unit of time, determined by the compressor's geometry and speed (stated by the manufacturer, e.g. in m³/h) |
313
Stredne ťažká
Why is it essential to observe the correct phase sequence for scroll compressors and screw compressors?
| 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 these types of compressors are sensitive to voltage drops. |
| Because changing the phase sequence would reverse the direction of rotation of the compressor rotors, which could result in damage to the compressors. |
314
Stredne ťažká
What compression ratio should each stage of a two-stage vapour-compression system have (rule of thumb)?
| Greater than 18 |
| Less than approximately 8 |
| Equal to 1 |
| Greater than 10 |
315
Stredne ťažká
Why is a shaft seal necessary in open-type compressors?
| To ensure the bearing remains lubricated |
| To protect the crankshaft bearing |
| To prevent air from entering and refrigerant from leaking out of the compressor |
| Only to prevent oil leakage |
316
Stredne ťažká
How can you check whether the liquid refrigerant is sufficiently subcooled?
| Check by touch whether the condenser outlet is noticeably colder than ambient |
| Check whether the whole evaporator surface is covered with an even layer of frost |
| Check whether the liquid distributor upstream of the evaporator feels warm |
| Compare the liquid-line temperature with the saturation temperature at the measured condensing pressure |
317
Stredne ťažká
Why is the compressor crankcase heated?
| To increase dissolution of refrigerant in the oil and improve its viscosity |
| To limit refrigerant migration into, and dissolution in, the oil during standstill |
| To keep the lubricating oil liquid |
| To dehydrate the oil |
318
Ľahká
What is the clearance (dead) volume of a reciprocating compressor?
| The space between the underside of the piston and the crankcase cover |
| The volume between the valve plate and the piston crown at top dead centre |
| The space between the side of the piston and the cylinder |
| The volume between the valve plate and the piston at bottom dead centre |
319
Stredne ťažká
What are compressor packs (racks)?
| Units with two-stage compressors |
| Several compressors connected in parallel on a common frame with common suction and discharge headers |
| Several air-cooled condensers |
| Sets of compressors connected in any configuration |
320
Stredne ťažká
What is the main advantage of multi-compressor packs?
| No need for compressor controls and safety devices |
| Low purchase cost and easy installation without special controls |
| A smaller refrigerant charge than a single-compressor system |
| Stepwise capacity matching to demand, plus redundancy |
321
Stredne ťažká
What is meant by the operating envelope (application range) of a compressor?
| A range determined by the evaporating temperature at a given ambient temperature |
| A range determined only by the evaporating temperature |
| The capacity, refrigerant type and dimensions of the compressor |
| The permissible range of evaporating and condensing temperatures (to, tk), or the corresponding pressures, within which the compressor may operate |
322
Stredne ťažká
What are the basic functions of oil in a compressor?
| Sealing leaks that develop in the installation |
| Increasing the cooling capacity of the refrigerant |
| Absorbing moisture from the refrigerant |
| Lubricating bearings and sliding surfaces, removing heat, and sealing clearances (e.g. between piston and cylinder, or rotors) |
323
Stredne ťažká
What are the most effective ways of controlling compressor cooling capacity?
| An expansion valve |
| Partially covering the evaporator |
| Pressure control valves |
| Changing the displacement: varying the rotational speed or unloading cylinders |
324
Stredne ťažká
What does hot-gas bypass capacity control involve?
| Part of the hot discharge gas is passed through a bypass valve to the suction side (or evaporator inlet), reducing the effective capacity |
| The compressor speed is varied |
| High-pressure liquid is injected into the suction to increase capacity |
| Bypass is not used for capacity control |
325
Stredne ťažká
What is the fundamental difference between hermetic and semi-hermetic compressors?
| The semi-hermetic casing is bolted (can be opened); the hermetic one is welded |
| The semi-hermetic compressor has no motor inside the casing |
| Both can be dismantled; they differ only in cooling capacity |
| Semi-hermetic compressors run more quietly as a complete unit |
326
Stredne ťažká
How does a scroll compressor work?
| A scroll compressor is also known as a turbo compressor. |
| It is a positive-displacement compressor in which compression results from the interaction of a fixed and an orbiting scroll. |
| It is a type of piston-type device. |
| It uses two screws to compress the refrigerant. |
327
Stredne ťažká
What physical process takes place in the evaporator?
| The refrigerant condenses |
| The refrigerant is subcooled as a liquid |
| The liquid refrigerant evaporates, absorbing heat, and the vapour is slightly superheated at the outlet |
| The secondary fluid (glycol, water) evaporates while the refrigerant condenses |
328
Stredne ťažká
What is the purpose of compressor capacity control?
| To ensure compressor lubrication |
| To match the cooling capacity to the current demand |
| To increase the condensing pressure |
| To match capacity to the condensing temperature |
329
Stredne ťažká
Why is inverter speed control advantageous for refrigeration compressors?
| It enables continuous, smooth control of cooling capacity |
| It increases compressor capacity above nominal at any frequency |
| It can be used with any compressor to ensure lubrication |
| Reducing the speed improves oil return to the compressor |
330
Stredne ťažká
Does the suction gas temperature affect the cooling capacity of the compressor?
| No – capacity depends only on the compressor displacement |
| Yes, but only in reciprocating compressors, not scroll |
| Yes, but only if the suction gas is deeply cooled |
| Yes – higher temperature lowers vapour density, mass flow and capacity |
331
Stredne ťažká
In the case of compressor units fitted with an oil level control system, is it necessary to install the compressors at the same height?
| No. |
| Only screw compressors. |
| Only scroll compressors. |
| Yes. |
332
Stredne ťažká
What functions does a compressor powered by the vehicle’s engine perform in a transport refrigeration system?
| The compressor compresses ambient air and increases the pressure of the refrigerant. |
| This compressor creates a vacuum on the suction side of the system whilst the vehicle’s engine is switched off. |
| This compressor draws in refrigerant vapour from the evaporator, compresses it and then forces it into the condenser whilst the vehicle’s engine is running. |
| This compressor condenses the refrigerant whilst the vehicle is in motion. |
333
Stredne ťažká
Which media most commonly absorb heat from the refrigerant in the condenser?
| Air or water |
| Ammonia |
| Air and CO₂ |
| Only a water–glycol mixture |
334
Stredne ťažká
What is the function of the condenser in refrigeration systems?
| Releasing only the heat from the compressor into the surroundings |
| Releasing only the heat absorbed in the evaporator into the surroundings |
| Absorption of heat rejected in the regenerative heat exchanger |
| Releasing to the environment the heat absorbed in the evaporator and the heat added during compression |
335
Stredne ťažká
If the refrigerant temperature on the high-pressure side is above its critical temperature, condensation…
| …does not occur |
| …always occurs regardless of temperature |
| …occurs provided a special condenser is used |
| …does not depend on temperature |
336
Stredne ťažká
How is liquid subcooling usually achieved in a refrigeration system?
| With an additional heat exchanger using liquid nitrogen |
| With hot high-pressure vapour |
| In the final section of the condenser (or in an additional subcooler) |
| By dissolving the refrigerant in oil |
337
Stredne ťažká
What is the purpose of condenser fan speed control?
| To disperse refrigerant in the event of a leak |
| To keep the condensing pressure at the correct level |
| Only to protect against exceeding the maximum condensing pressure |
| To reduce energy efficiency |
338
Stredne ťažká
Which international agreement introduced the global phase-down of HFC production and consumption?
| The Kigali Amendment to the Montreal Protocol |
| The Paris Agreement |
| The Vienna Convention for the Protection of the Ozone Layer |
| The Kyoto Protocol |
339
Stredne ťažká
Which international treaty governs the phase-out of ozone-depleting substances (CFCs, HCFCs)?
| The Stockholm Convention |
| The Paris Agreement |
| The Montreal Protocol |
| The UN Framework Convention on Climate Change (UNFCCC) |
340
Ťažká
What is the basis of the GWP values in Regulation (EU) 2024/573?
| AR4 for all substances |
| For HFCs (Annex I) – mainly the IPCC Fourth Assessment Report (AR4); for HFOs and non-fluorinated substances (Annexes II and VI) – the Sixth Assessment Report (AR6) |
| Each Member State sets its own GWP values |
| AR6 for all substances |
341
Ťažká
An air conditioner (not hermetically sealed) contains 2.5 kg of R410A (GWP 2088). How often must it be checked for leaks?
| Every 6 months |
| No checks required (below 3 kg) |
| At least every 12 months (5.22 t CO₂ eq) |
| Every 3 months |
342
Ťažká
When is labelled hermetically sealed equipment containing HFCs (Annex I) exempt from leak checks?
| When it contains less than 5 t CO₂ eq |
| When it contains less than 10 t CO₂ eq, and in residential buildings also when it contains less than 3 kg of F-gases |
| Never – hermetically sealed equipment is always checked |
| Always, regardless of charge |
343
Ťažká
Is a chiller containing 50 kg of R1234ze(E) subject to leak checks under Regulation (EU) 2024/573?
| Yes – at least every 6 months (every 12 months with a leakage detection system) |
| No – HFOs are not subject to leak checks |
| No – the threshold is 5 t CO₂ eq and 50 kg of R1234ze is below 1 t CO₂ eq |
| Yes – every 12 months, because its GWP is low |
344
Ťažká
In 2026, may an existing refrigeration installation using R404A (GWP 3922) be topped up with virgin refrigerant?
| No – only reclaimed or recycled R404A is allowed (until 1 January 2030) |
| Yes – bans apply only to new equipment |
| Yes – the ban applies only to equipment ≥40 t CO₂ eq |
| Yes, if the equipment has a leakage detection system |
345
Ťažká
After 1 January 2026, may an R410A (GWP 2088) air conditioner be serviced using virgin R410A?
| No – the ban covers all HFCs |
| Yes – the servicing ban for air conditioners and heat pumps covers F-gases with GWP ≥ 2500 |
| Only with reclaimed refrigerant |
| No – the ban covers all refrigerants with GWP ≥ 750 |
346
Stredne ťažká
Can HFC refrigerant recovered during a repair be put straight back into the same equipment without any cleaning (filtering/drying)?
| Yes, if less than 24 hours have passed |
| Yes, always |
| Yes, if the operator agrees |
| No – recovered F-gas may be used for filling only after it has been recycled or reclaimed |
347
Stredne ťažká
Who may purchase HFCs for servicing refrigeration equipment?
| Any adult |
| Only the equipment operator |
| Any business |
| Only a person holding the relevant certificate or an undertaking employing such persons |
348
Stredne ťažká
Under what condition may non-hermetically sealed split air conditioning charged with F-gas be sold to an end user?
| When evidence is provided that installation will be carried out by a certified undertaking |
| Only if the unit contains less than 3 kg of refrigerant |
| Unconditionally |
| When the user signs a statement that they will install it themselves |
349
Stredne ťažká
By when must the holder of an F-gas certificate issued under Regulation (EU) No 517/2014 first complete refresher training or an evaluation process?
| By 12 March 2025 |
| By 31 December 2030 |
| By 12 March 2029 (and then at least every 7 years) |
| Never – the certificate is valid indefinitely |
350
Stredne ťažká
What must the holder of a Category I certificate (Regulation 2015/2067) do to continue using it?
| Apply for an extension without training |
| Update their knowledge and skills to the level of Certificate A1 (Annex I to Regulation 2024/2215) |
| Update their knowledge to the level of Certificate E |
| Nothing – Category I automatically becomes A1 |
351
Stredne ťažká
What does Certificate C under Implementing Regulation (EU) 2024/2215 authorise?
| Recovery of F-gases from equipment <3 kg |
| All activities in relation to CO₂ |
| All activities in Article 2(1) in relation to ammonia (NH₃) |
| Leak checks without breaking into the circuit |
352
Stredne ťažká
May a person enrolled in a certification training course carry out certified activities?
| Yes – with no time limit, if employed by a certified company |
| Yes – independently, for 6 months |
| No, never |
| Yes – under the supervision of a certified person, for no more than 24 months in total |
353
Stredne ťažká
How long must the operator keep the records of equipment subject to leak checks, if they are not kept in a national database?
| At least 2 years |
| At least 5 years |
| Until the equipment is decommissioned |
| At least 1 year |
354
Ťažká
Since 1 January 2025, may a new single-split air conditioner containing 1.5 kg of R410A be placed on the market?
| No – single splits <3 kg with F-gases of GWP ≥ 750 are banned |
| Yes – the ban applies from 2029 |
| Yes – the ban applies only to units >12 kW |
| Yes, if the unit is hermetically sealed |
355
Ťažká
From when is it prohibited to place on the market split air-to-air systems up to 12 kW containing F-gases with GWP ≥150 (unless required for safety)?
| From 1 January 2027 |
| From 1 January 2035 |
| From 1 January 2025 |
| From 1 January 2029 |
356
Ťažká
Which persistent atmospheric degradation product of R1234yf is classed as a PFAS?
| Ozone |
| Carbonic acid |
| Carbon dioxide |
| Trifluoroacetic acid (TFA) |
357
Stredne ťažká
What distinguishes class 2L refrigerants from class 2?
| A maximum burning velocity of no more than 10 cm/s |
| Heat of combustion above 19 MJ/kg |
| Higher toxicity |
| No lower flammability limit |
358
Stredne ťažká
What is the lower flammability limit (LFL) of propane R290?
| Approx. 1.8 kg/m³ |
| Approx. 0.38 kg/m³ |
| Approx. 0.307 kg/m³ |
| Approx. 0.038 kg/m³ (approx. 2.1% by volume) |
359
Ťažká
What is the maximum R290 charge per circuit of a commercial refrigerating appliance (e.g. a cabinet) according to EN IEC 60335-2-89:2022?
| 1.5 kg |
| 150 g |
| 13 × LFL ≈ 494 g |
| 1.2 kg |
360
Ťažká
Calculate the maximum R32 charge (LFL = 0.307 kg/m³) for a wall-mounted air conditioner (h₀ = 1.8 m) in a 20 m² room using m_max = 2.5 × LFL^1.25 × h₀ × A^0.5.
| approx. 4.6 kg |
| approx. 1.5 kg |
| approx. 13.8 kg |
| approx. 0.46 kg |
361
Stredne ťažká
Equipment marked 'Ex II 3G' may be used in zone:
| 0 |
| 20 (dusts) |
| 1 |
| 2 (explosive gas atmosphere unlikely and short-lived) |
362
Stredne ťažká
How is explosion hazard zone 2 defined?
| An area where flammable refrigerants are never used |
| An explosive atmosphere is not likely in normal operation and, if it occurs, persists only for a short period |
| An explosive atmosphere is present continuously or for long periods |
| An explosive atmosphere is likely to occur in normal operation |
363
Stredne ťažká
Under which UN number is propane (R290) carried under ADR?
| UN 3252 |
| UN 1978 |
| UN 3337 |
| UN 1005 |
364
Ťažká
What is the maximum quantity of R290 (class 2, group F) that may be carried per transport unit under the ADR 1.1.3.6 exemption?
| 20 kg |
| 333 kg |
| Unlimited |
| 1000 kg |
365
Stredne ťažká
At what concentration should a portable flammable gas detector used for R290 work raise an alarm at the latest?
| No higher than 25% of LFL |
| At 5% propane by volume |
| At 100% of LFL |
| At 150% of LFL |
366
Stredne ťažká
How should a recovery cylinder be prepared before filling it with a hydrocarbon refrigerant?
| No preparation is needed |
| Partly fill it with nitrogen to 5 bar |
| Evacuate it (no air) and label it for the specific flammable refrigerant |
| Purge it with compressed air |
367
Stredne ťažká
What is the correct approach in a risk analysis before work on an HC system?
| First eliminate hazard sources (e.g. ignition sources); where this is not possible, identify them and apply mitigating measures (ventilation, detection, PPE) |
| The risk analysis is done after the work is finished |
| Having a fire extinguisher is sufficient |
| First select PPE, then possibly remove ignition sources |
368
Ťažká
What is the charge limit m₃ = 130 m³ × LFL for R290 (LFL = 0.038 kg/m³) according to IEC 60335-2-40?
| approx. 13 kg |
| approx. 0.99 kg |
| approx. 4.94 kg |
| approx. 0.15 kg |
369
Stredne ťažká
Which property of ammonia helps people detect a leak early?
| It is odourless |
| It is denser than air |
| It is yellow in air |
| A very low odour threshold (a few ppm) |
370
Stredne ťažká
What hazard does a large CO₂ leak in an enclosed room pose to people?
| Formation of hydrogen fluoride |
| CO₂ is completely safe |
| Accumulation near the floor and asphyxiating/toxic effects at high concentrations |
| Explosion of the mixture with air |
371
Ťažká
Why does the efficiency of transcritical CO₂ systems fall in warm climates, and how is this mitigated?
| CO₂ freezes in the gas cooler – heaters are used |
| Gas cooler pressure drops – extra charge is added |
| At high ambient temperatures the system operates transcritically with large throttling losses – parallel compression and ejectors are used, among others |
| Efficiency does not depend on climate |
372
Stredne ťažká
What is floating head pressure and what does it achieve?
| It means switching condenser fans off periodically |
| It lets the condensing pressure fall with ambient temperature, reducing compressor work and raising COP (requires an expansion valve that works at a small pressure difference) |
| It increases subcooling by flooding the condenser |
| It keeps a constant high condensing pressure all year |
373
Stredne ťažká
How do SEER/SCOP differ from EER/COP?
| There is no difference – they are synonyms |
| EER/COP are always higher than SEER/SCOP |
| SEER/SCOP are seasonal indicators accounting for part load and climate (EN 14825); EER/COP refer to a single operating point (EN 14511) |
| SEER/SCOP apply only to natural-refrigerant equipment |
374
Stredne ťažká
Which design approach can significantly reduce the F-gas charge of a large refrigeration installation?
| Adding a second liquid receiver |
| An indirect (secondary-coolant) system or a cascade with a natural refrigerant in the low stage, plus heat exchangers with small internal volume |
| Larger liquid-line diameters |
| Omitting pipe insulation |
375
Stredne ťažká
Why must the charge of small, critically charged R290 systems be weighed to within a few grams during service?
| Small charge deviations significantly change superheat/subcooling and efficiency, and overcharge increases the risk in a leak |
| Because R290 is more expensive than HFCs |
| Because scales are not needed – charging is done by sight glass |
| Because extra R290 improves efficiency |
376
Stredne ťažká
Which information must be entered in the equipment records after a leak check?
| The date and result of the check and the identity of the undertaking and person who performed it (with certificate number) |
| Only the date of the check |
| Only the operator's signature |
| Only the equipment's energy consumption |
377
Stredne ťažká
What must be done when an indirect method (e.g. parameter analysis) indicates a possible leak?
| Nothing – indirect methods are sufficient |
| Record it and check at the next periodic inspection |
| Top up the refrigerant and end the check |
| Carry out a direct-method examination to locate the leak |