F-Gas English Low GWP
Všetky otázky
HFC | Flammable | CO₂ | NH₃
Ľahké otázky |
Stredne ťažké otázky |
Ťažké otázky
1
Stredne ťažká
What is R1270?
| n-Butane |
| Isobutane |
| Propane |
| Propene (propylene) |
2
Stredne ťažká
What is the main design difference in hydrocarbon refrigeration systems?
| Lower energy efficiency |
| No need for safety measures |
| Higher operating pressures |
| The need to eliminate ignition sources and limit the charge because of the refrigerant's flammability |
3
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 |
4
Stredne ťažká
What distinguishes class 2L refrigerants from class 2?
| Heat of combustion above 19 MJ/kg |
| Higher toxicity |
| No lower flammability limit |
| A maximum burning velocity of no more than 10 cm/s |
5
Stredne ťažká
What is the lower flammability limit (LFL) of propane R290?
| Approx. 0.307 kg/m³ |
| Approx. 0.038 kg/m³ (approx. 2.1% by volume) |
| Approx. 1.8 kg/m³ |
| Approx. 0.38 kg/m³ |
6
Stredne ťažká
Equipment marked 'Ex II 3G' may be used in zone:
| 1 |
| 0 |
| 20 (dusts) |
| 2 (explosive gas atmosphere unlikely and short-lived) |
7
Stredne ťažká
How is explosion hazard zone 2 defined?
| An explosive atmosphere is present continuously or for long periods |
| An area where flammable refrigerants are never used |
| An explosive atmosphere is likely to occur in normal operation |
| An explosive atmosphere is not likely in normal operation and, if it occurs, persists only for a short period |
8
Stredne ťažká
Under which UN number is propane (R290) carried under ADR?
| UN 3337 |
| UN 1978 |
| UN 3252 |
| UN 1005 |
9
Stredne ťažká
At what concentration should a portable flammable gas detector used for R290 work raise an alarm at the latest?
| At 5% propane by volume |
| No higher than 25% of LFL |
| At 150% of LFL |
| At 100% of LFL |
10
Stredne ťažká
How should a recovery cylinder be prepared before filling it with a hydrocarbon refrigerant?
| 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 |
| No preparation is needed |
11
Stredne ťažká
What is the correct approach in a risk analysis before work on an HC system?
| Having a fire extinguisher is sufficient |
| First select PPE, then possibly remove ignition sources |
| The risk analysis is done after the work is finished |
| First eliminate hazard sources (e.g. ignition sources); where this is not possible, identify them and apply mitigating measures (ventilation, detection, PPE) |
12
Stredne ťažká
Why must the charge of small, critically charged R290 systems be weighed to within a few grams during service?
| Because scales are not needed – charging is done by sight glass |
| Because extra R290 improves efficiency |
| Because R290 is more expensive than HFCs |
| Small charge deviations significantly change superheat/subcooling and efficiency, and overcharge increases the risk in a leak |