When the pressure gets low, the boiling-point becomes low. 气压变低，沸点就变低。

相似题目

• The purpose of the low pressure cut-out switch is to （）.

  A . maintain liquid refrigerant at the suction of the compressor B . maintain a preset suction pressure to the compressor C . start and stop the compressor at preset operating pressures D . operate at minimum efficiency

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• The sensing line for the low pressure cutout switch to a refrigeration system is located （）.

  A . in the chill box B . before the receiver C . on the suction side of the compressor D . on the discharge side of the compressor

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• The device used for low-pressure control and high-pressure cutout on a compressor is called （）.

  A . cutout B . controller switch C . pressure controller D . cutout switch

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• Generally speaking，you should expect to find low atmospheric pressure prevailing in the earth’s（）.

  A . equatorial area B . polar regions C . mid-latitudes D . All of the above

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• Compared to a low pressure system，generally the air in a high is（）.

  A . warmer，less dense，and less stable B . cool，more dense，and drier C . muggy and cloudy D . extremely moist with high relative humidity

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• On small, low pressure, air compressors, the cylinders are usually lubricated by the （）.

  A . splash method B . mechanical force feed lubricators C . detached sump method D . internal cooling passages in the crankshafts and connecting rod

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• In the Southern Hemisphere winds in a low pressure system rotate in a（）.

  A . clockwise direction B . northeasterly direction C . northerly direction D . counterclockwise directio

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• The major difference between the discharge and suction valves installed in most low pressure, reciprocating air compressors is that（）

  A、one valve seats upwards, while the other seats downwards B、the reed valves used on the discharge are made substantially thicker and heavier than thesuction valves C、the suction valve springs exert a greater tension than the discharge valve springs D、the discharge valve springs exert a greater tension than the suction valve springs

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• The refrigeration system low pressure cutout switch is actuated by （）.

  A . an electric system manager B . a sensing bulb at the tail coil of the evaporator C . pressure changes in the suction line D . failure of the king solenoid valve

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• Which of the listed components is considered to separate the high pressure side of a refrigeration cycle from the low pressure side of the cycle?（）

  A . The condenser and the expansion valve B . The king valve and the solenoid valve C . The compressor and the expansion valve D . The condenser and the solenoid valve

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• In a compression refrigeration plant the refrigerant is under low pressure in the （） and under high pressure in the （）.

  A . compressor；condenser B . condenser；evaporator C . throttle valve；evaporator D . evaporator；condenser

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• The efficiency and output capacity of a low pressure distilling plant will be reduced if the last effect shell （）

  A . pressure does not fluctuate rapidly B . pressure remains steady and unchanged C . brine density does not exceed 1~5 D . brine density is too low

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• In order to accurately measure very low pressures, which of the instruments listed should be used?（）

  A . Compound gage B . Bonrdon tube C . Manometer D . Deadweight gage

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• Leaky exhaust valve will result in which of the following?（） (1) high exhaust temperature; (2) low compression pressure; (3) low firing pressure.

  A . (1) and (2) B . (1) only C . (2) only D . (1),(2) and (3)

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• According to Buys Ballot’s law，when an observer in the Northern Hemisphere experiences a northwest wind，the center of low pressure is located to the（）.

  A . northeast B . west-southwest C . northwest D . south-southeast

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• The passing of a low pressure system can be determined by periodically checking the（）.

  A . Thermometer B . Hygrometer C . Barometer D . Anemometer

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• If an observer in the Northern Hemisphere faces the surface wind，the center of low pressure is to his（）.

  A . left，slightly behind him B . right，slightly behind him C . left，slightly in front of him D . right，slightly in front of him

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• If a refrigeration crankcase compressor were short cycling on the low pressure cutout switch, the cause might be that the （）.

  A . system was overcharged with refrigerant B . system was low on refrigerant C . suction valves were leaking slightly D . relief valve was leaking slightly

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• The purpose of the refrigeration system low pressure cutout switch is to （）

  A . protect the compressor from liquid flood back B . protect the compressor from low discharge pressure C . start and stop the compressor upon system demand D . start the compressor after a drop in the evaporator pressure

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• 207. The greater the pressure difference between a high and a low pressure center, the ______ .

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• When having a dinner with new friends, what is a low-context person hoping to get out of the dinner?

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• The refrigeration system low pressure cutout switch is actuated by______.

  A.an electric system manager B.a sensing bulb at the tail coil of the evaporator C.pressure changes in the suction line D.failure of the king solenoid valve

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• Leaky exhaust valve will result in which of the following？①high exhausttemperature ②low compression ③low firing pressure

  A.① and ② B.② and ③ C.① ② and ③

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• 城市气体消耗少时，向城市的供气量小于干线的流量（也即末段起点的流量），多余的气体积存在末段管路中，使末段的压力上升。When urban gas consumption is low, the gas supply to the city is less than the flow of the trunk （i.e. the flow at the beginning of the last section), and the excess gas is stored in the last section of the pipeline, causing the pressure at the last section to rise.

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