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
The major source of chemical contaminants in hydraulic fluid is （）.
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?（）
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
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 （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
A pressure drop through the refrigerant liquid line may cause （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.