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
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
A salinity indicator is used to determine the （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.