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What is the common refrigerant used in absorption refrigeration machines?
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Which of the following metering devices is used on low-pressure chillers?
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Commercial A/C
Final Test
| Question | Answer |
|---|---|
| What is the common refrigerant used in absorption refrigeration machines? | Water |
| Which of the following metering devices is used on low-pressure chillers? | 1) high float side 2) low side float 3) orifice |
| The purge unit on a low-pressure chiller removes | Noncondensables |
| List type of metering device used on high pressure chiller? | 1) TXV 2) orifice 3) electronic stop |
| What is the purpose of the purge unit? | Remove non-condensable |
| Two basic categories of chillers are? | Compression cycle and absorption |
| Four compressors commercial A/C system | 1) scroll 2) screw 3) reciprocate 4) centrifugal |
| Control the capacity of a screw compressor | Slide valve |
| The compressor used for low pressure chillers | Centrifugal |
| How capacity control accomplished on a centrifugal compressor? | Inlet vane |
| The type of refrigerants used in low pressure chiller | R-11, R-113, R-123 |
| Screw compressors can range from _____tons | 50 to 700 tons |
| Chillers operate with a chill water supply temp of ____deg F and a return water temp of___deg F | 45 deg F, 55 deg F |
| Three environment functions | 1) size space 2) Geographical location 3) specific location |
| ASHRA Winter/Summer | 75F deg. 50 RH |
| Three environment functions | 1) temperature 2) Humid 3) air flow |
| Absorption refrigeration cycle components | 1) evaporator 2) absorber 3) concentrator 4) condenser |
| Type of centrifugal fan | 1) forward-curved 2) backward-curved 3) backward-inclined 4) airfoil |
| Most efficient of centrifugal fan | Airfoil |
| Start sequence chiller system 1 and 2 | 1) systems switch closes, energizing chilled-water pump contractor coil 2) chilled-water pump starts. Auxiliary contacts close and start condenser water pump |
| Start sequence chiller system 3 and 4 | 3) auxiliary contacts close and start cooling tower fan 4) power is provided to flow switches and to chiller field-control circuit when cooling tower fan is started |
| Output device final condition? | Feedback |
| Type of cooling towers | 1) natural-draft 2) forced-draft 3) induced-draft |
| Two types of fan are used for cooling tower | 1) propeller 2) centrifugal |
| Three types of axial fan | 1) propeller 2) tube-axial 3) vane-axial |
| Secondary HVAC system: Three Catogries | 1)All air system 2) 3) |
| Damper control and VAV system, how do they control? | cooling, t-stat's output varies to modulate the VAV box damper change from min to max, increase air 55F balance heat gain. Heating, air volume decrease to min., heating is introduced by heheat coil, baseborad radiation or both |
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toolegit