单项选择题
If an operating bilge pump is developing good vacuum, but is unable to discharge any water, which of the following problems is the most probable cause?（）
A.The wearing rings are excessively worn
B.The suction strainer is clogged
C.The discharge valve is clogged
D.The shaft is worn
相关考题
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单项选择题
The sudden reduction of pressure occurring within the crankcase of a refrigeration compressor during starting causes the （）.
A.sudden evaporation of wax crystals in the lubricant
B.sudden evaporation of entrapped air in the lubricant
C.release of refrigerant from the oil/refrigerant mixture
D.release of dissolved lubricant from the refrigerant -
单项选择题
One of the consequences in continuing to operate a centrifugal bilge pump with the discharge valve closed, is that the （）.
A.motor overload will open
B.relief valve will open
C.pump will overheat
D.motor will overheat -
单项选择题
Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?（）
A.The liquid receiver functions to collect and remove non-condensable gases
B.A thermostatic expansion valve is used to control refrigerated space temperature
C.Refrigerant temperature in an evaporator is directly related to refrigerant pressure
D.Dehydrators must be used continuously in a refrigeration system
