默认题库 - 船舶辅助机械 - 查题吧

单选题

Which of the problems listed could be indicated if a sight glass in the refrigerant liquid line is full of bubbles?（）

A. Proper refrigerant charge
B. Faulty expansion valve
C. Insufficient refrigerant
D. Solenoid valve stuck ope

单选题

As the refrigerant passes through the valve orifice, its pressure is reduced and part of the refrigerant turns into （）.

A. liquid
B. oily mixture
C. emulsion
D. vapor

单选题

Among the basic categories of equipment, which of the following are used to allow the hydraulic energy to be controlled?（）

A. hydraulic pumps
B. valves
C. hydraulic cylinders
D. hydraulic motor

单选题

While flowing through the volute in a centrifugal pump, part of the （） energy of the liquid is converted to （） energy.

A. kinetic；pressure
B. kinetic；essential
C. pressure；kinetic
D. pressure；height

单选题

One distinct advantage of flash type evaporators, as compared to most other evaporators, is that in a flash evaporator （）.

A. high temperature distillate can be re- circulated to induce additional flashing
B. scale formation is not a severe problem
C. cold shocking is more effective in removing scale
D. water purity is greatly increased at high capacity

单选题

When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.

A. increase the amount of cooling water to the condenser
B. decrease the amount of cooling water to the condenser
C. add more refrigerant to the system
D. remove some refrigerant from the system

单选题

Increased internal leakage, in addition to poor hydraulic system response,and inadequate lubrication, is the result of （）.

A. pump bearings in poor condition
B. excessively worn actuator-piston packing
C. broken directional control valve centering springs
D. low hydraulic oil viscosity

单选题

Which of the following chemicals will be used where protection against caustic cracking is required in boiler treatment?（）

A. Sodium hydroxide
B. Sodium carbonate
C. Sodium nitrate
D. Sodium polyphosphate

单选题

The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.

A. specific gravity
B. viscosity
C. S E number
D. hydrolytic stability

单选题

To absorb the wear resulting from impeller rotation and abrasives in the liquid, a centrifugal pump is usually fitted with （）.

A. lantern rings
B. bearings
C. easing volutes
D. wearing ring

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