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
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably 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?（）
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
A salinity indicator is used to determine the （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
The output volume of a positive fixed displacement pump can be changed only by （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
The general purpose of a heat exchanger is to （）.