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)?
| t |
| lb (pound) |
| kg |
| N |
2
Ľahká
The refrigerant absorbs heat when…
| …it condenses |
| …it evaporates |
| …it is subcooled |
| …it freezes |
3
Ľahká
What does the GWP indicator mean?
| Ozone depletion potential |
| The ability of a substance to restore the ozone layer |
| 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 |
| The annual rise in mean air temperature caused by the emission of 1 kg of the gas |
4
Ľahká
What is the main function of a safety valve?
| Discharges refrigerant when the set pressure is exceeded |
| It controls the oil level in the compressor |
| It monitors the moisture content of the refrigerant |
| Prevents the evaporator from freezing |
5
Ľahká
What is the unit of pressure in the International System of Units (SI)?
| atm (standard atmosphere) |
| psi (pound per square inch) |
| Pa (pascal) |
| bar (gauge) |
6
Ľahká
What is the log(p)-h diagram for CO₂ used for?
| To regulate pressure |
| For analysing thermodynamic processes in a refrigeration system |
| To detect leaks |
| To measure temperature |
7
Ľahká
What can be read from the log(p)-h graph?
| Only the humidity |
| Pressure, enthalpy, temperature and state of the refrigerant |
| Only the temperature |
| Only the amount of refrigerant |
8
Ľahká
What are CO₂ saturation tables used for?
| To determine the oil quantity |
| To regulate the compressor |
| To determine the relationship between temperature and pressure at saturation |
| To measure humidity |
9
Ľahká
What does the CO₂ saturation state mean?
| Equilibrium between the liquid and vapour phases |
| Dry ice state |
| A state in which the refrigerant is only a gas |
| A state of high pressure |
10
Ľahká
Why is understanding the log(p)-h graph particularly important for CO₂?
| As CO₂ systems operate in different modes (sub- and transcritical) and require detailed analysis |
| It doesn’t matter |
| It is only used for design purposes |
| It only applies to NH₃ |
11
Ľahká
Why do CO₂ systems require precise pressure control?
| Due to low pressures |
| They do not require control |
| Due to significant pressure changes with temperature fluctuations |
| Because there are no valves |
12
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 |
13
Ľahká
What is the correct procedure for recovering R717 from a system?
| 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 |
| The gas can be released into the atmosphere |
14
Ľahká
How should R717 (NH₃) be stored?
| In sealed, labelled containers, in a cool and well-ventilated place |
| In unmarked plastic containers |
| In any open containers |
| Near heat sources |
15
Ľahká
What is the main hazard associated with an R717 leak during maintenance work?
| Damage to electrical equipment only |
| Increased cooling efficiency |
| Toxic to humans and may cause chemical burns |
| No risk whatsoever |
16
Ľahká
What personal protective equipment is required when working with NH₃?
| Workwear only |
| Only a safety helmet |
| No requirements |
| Safety goggles, gloves and respiratory protective equipment |
17
Ľahká
How do system leaks affect compressor energy efficiency?
| 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) |
| They improve efficiency because condensing pressure drops |
18
Ľahká
How does a dirty condenser affect the operation of the refrigeration system?
| It has no effect |
| It lowers the condensing pressure |
| It improves efficiency |
| Causes an increase in pressure and energy consumption by the compressor |
19
Ľahká
Why is adequate airflow through an air-cooled condenser important?
| It doesn't matter |
| It affects only noise |
| The lower the airflow, the lower the condensing pressure |
| It ensures effective heat rejection and low condensing pressure |
20
Ľahká
How does the presence of limescale in a water-cooled condenser affect performance?
| It lowers the condensation temperature |
| Impairs heat exchange and increases energy consumption |
| It improves heat transfer |
| It has no effect |
21
Ľahká
How do condenser leaks affect energy efficiency?
| They improve efficiency |
| They lower the temperature |
| Have no effect |
| Causes refrigerant loss and a drop in efficiency |
22
Ľahká
How important is the correct positioning of an air-cooled condenser?
| It doesn’t matter |
| It should be installed in a well-ventilated area with unobstructed airflow |
| It should be close to heat sources |
| It should be housed in a small room |
23
Ľahká
How does hot air recirculation affect the condenser?
| It has no effect |
| Impairs cooling and increases energy consumption |
| It improves efficiency |
| It reduces the pressure |
24
Ľahká
How does evaporator icing affect the system’s operation?
| It lowers the condensation temperature |
| It has no effect |
| It improves cooling performance |
| Impairs heat exchange and increases energy consumption |
25
Ľahká
How does dirt on the evaporator surface affect its performance?
| It improves efficiency |
| It reduces the pressure |
| It has no effect |
| Impairs heat exchange and increases energy consumption |
26
Ľahká
What maintenance task is crucial for the evaporator?
| Regular cleaning and defrosting |
| Lack of maintenance |
| Reduced airflow |
| Increasing the refrigerant charge |
27
Ľahká
How does superheat at the evaporator outlet affect efficiency?
| It always improves performance |
| Excessive superheat reduces energy efficiency |
| It only causes a temperature drop |
| It has no effect |
28
Ľahká
How do leaks in the evaporator affect efficiency?
| Improves performance |
| These cause refrigerant loss and a drop in efficiency |
| Have no effect |
| Increase capacity |
29
Ľahká
How important is correct expansion valve adjustment?
| Ensures optimal evaporator charge and improves efficiency |
| Causes leaks |
| It doesn’t matter |
| It increases energy consumption |
30
Ľahká
How does inadequate insulation of suction (or secondary-coolant) pipes affect evaporator performance?
| It improves efficiency |
| It lowers the condensing temperature |
| It has no effect |
| It causes cooling losses and increased energy use |
31
Ľahká
How does correct TEV adjustment affect system energy efficiency?
| It increases energy use |
| It causes leaks |
| It has no effect |
| It ensures optimal superheat and improves efficiency |
32
Ľahká
What happens if the superheat set by the TEV is too high?
| Cooling efficiency will improve |
| The refrigerant charge will increase |
| It has no effect |
| Efficiency will drop because the evaporator is not being fully utilised |
33
Ľahká
How do contaminants in the system affect the operation of the TEV?
| Have no effect |
| They improve its performance |
| They can cause it to become blocked and reduce efficiency |
| They lower the temperature |
34
Ľahká
What role does the filter-drier play in terms of system efficiency?
| It lowers the temperature |
| It increases the amount of refrigerant |
| Removes moisture and contaminants, improving the system’s efficiency |
| It doesn’t matter |
35
Ľahká
How does proper insulation of components (e.g. pipes near the TEV) affect the system?
| It doesn’t matter |
| It causes leaks |
| Prevents unwanted heat gains and improves efficiency |
| It increases energy consumption |
36
Ľahká
How important is it to check the operation of the condensing pressure control valve in the system?
| It increases energy consumption |
| It has no effect |
| It causes a significant rise in temperature |
| Ensures operation within the optimum pressure range and reduces energy losses |
37
Ľahká
How does the correct selection of a TEV affect energy efficiency?
| Ensures the system is matched to its capacity and operates optimally |
| It increases the amount of refrigerant |
| It doesn’t matter |
| It lowers the temperature |
38
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 |
39
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 |
40
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 not required for hermetically sealed systems |
| Labelling is required only in technical rooms |
41
Ľahká
What are the potential consequences of using unsuitable connections in a system containing a flammable substance?
| No impact on safety |
| Risk of leakage and the formation of an explosive mixture |
| Merely installation difficulties |
| Merely a reduction in efficiency |
42
Ľahká
How should an employee respond when a gas alarm is triggered?
| Leave the room immediately and notify their supervisor |
| Switch off the system and wait for the alarm to stop |
| Reduce the pressure in the system |
| Carry on working until they see a leak |
43
Ľahká
Gas detectors should be installed in rooms where:
| Ventilation is natural |
| Any refrigerant is present, regardless of the quantity |
| The amount of refrigerant exceeds a specified permissible threshold |
| The room is less than 5 m² |
44
Ľahká
How do leaks affect systems using flammable refrigerants?
| Have no effect |
| They cause refrigerant loss, reduced efficiency and a fire hazard |
| They improve efficiency |
| They lower the temperature |
45
Ľahká
Why is the cleanliness of heat exchangers in HC systems important?
| It increases the pressure |
| Causes leaks |
| It doesn’t matter |
| It improves heat transfer and reduces energy consumption |
46
Ľahká
What maintenance measures improve the efficiency of a system using a flammable refrigerant?
| Disabling safety devices |
| Lack of servicing |
| Regular checks for leaks and operating parameters |
| Increasing the refrigerant charge |
47
Ľahká
How does the correct selection of components affect a system using a flammable refrigerant?
| It doesn’t matter |
| It lowers the temperature |
| It increases the amount of refrigerant |
| It ensures safe and optimal operation and minimises energy losses |
48
Ľahká
Why is it important to use the correct service tools in HC systems?
| It doesn’t matter |
| Causes leaks |
| It ensures operational safety and reduces refrigerant losses |
| It increases energy consumption |
49
Ľahká
How does pipe insulation affect the efficiency of systems containing HC?
| It doesn’t matter |
| It increases the pressure |
| It reduces energy losses and improves efficiency |
| Causes leaks |
50
Ľahká
What is the base unit of temperature according to the International System of Units (Système International d’Unités)?
| °R |
| K |
| °F |
| °C |
51
Ľahká
What is the superheat of refrigerant vapour?
| The difference between the actual vapour temperature and the saturation temperature corresponding to its pressure (expressed in K) |
| The difference between the condensing temperature and the ambient temperature |
| The difference between the saturation temperature and the actual liquid temperature in the liquid line |
| The amount of heat required to evaporate a liquid |
52
Ľahká
What is the compression ratio of a compressor?
| The ratio of suction pressure to discharge pressure (po/pc) |
| 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 discharge pressure to the effective capacity of the compressor (p/Vk) |
53
Ľahká
What is the theoretical displacement (swept volume flow) of a compressor?
| The volume of refrigerant flowing in one piston cycle under actual operating conditions |
| 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) |
| A value expressed by the coefficient of performance (COP) |
| The volume of a single cylinder in cm³ |
54
Ľahká
What is the clearance (dead) volume of a reciprocating compressor?
| The volume between the valve plate and the piston crown at top dead centre |
| The space between the underside of the piston and the crankcase cover |
| The volume between the valve plate and the piston at bottom dead centre |
| The space between the side of the piston and the cylinder |