A.primarily to lubricate the shaft seals
B.due to the inability of this type of pump to lift water to cover the suction (eye) of the impeller
C.to initially unload the pump by having its head pressure equal to discharge pressure
D.in order to overcome the potential energy of water in the discharge line
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A.humidification
B.dehumidification
C.vaporization
D.evaporation
A.latent heat of vaporization
B.sensible heat
C.refrigerating effect
D.specific heat of vaporization
A.Ball float
B.Thermostatic
C.Bimetallic
D.Impulse
A.a gas mask suitable for protection against each refrigerant used, or a self contained breathing apparatus must be provided
B.it is the sole responsibility of the chief engineer to ascertain that all members of the engineering department are familiar with the use of gas masks or breathing apparatus
C.spare charges shall be carried for at least 50% of each size and variety of gas masks and/or self contained breathing apparatus
D.all of the above
A.to inject cleaning additives when the bilges are extremely dirty
B.when the main condenser becomes fouled, in order to provide additional cooling water circulation
C.to connect the rose box to the independent bilge suction
D.if the bilges become flooded and they can not be emptied by any other means
最新試題
Low compressor head pressure in a refrigeration system can be caused by（）.
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
A pressure drop through the refrigerant liquid line may cause （）.