A.Vapor pockets formed in the suction flow stream
B.Rough easing volute surfaces
C.Worn wearing rings
D.Heavy fluid in the flow stream
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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
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
最新試題
Low compressor head pressure in a refrigeration system can be caused by（）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
The usual symptoms of cavitation in a centrifugal pump is （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
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 （）.
A salinity indicator is used to determine the （）.