单项选择题An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().

A.oil foaming in the compressor
B.higher than normal suction and discharge pressures with a higher box temperature
C.higher than normal discharge pressure with a normal box temperature
D.the compressor to run continuously


您可能感兴趣的试卷

你可能感兴趣的试题

1.单项选择题When the steering gear is in operation, you should ().

A.check hydraulic oil levels every hour
B.check the rams for overheating
C.check for excessive oil leakage from rams
D.drain water from telemotor cylinders each watch

2.单项选择题The oil in a cargo winch gear box should be sampled periodically to ().

A.prevent the gear box from leaking
B.prevent the oil from becoming inflammable
C.make sure it has not become contaminated
D.make sure the motor bearings are lubricated

3.单项选择题A spur gear pump should be operated with the discharge valves ().

A.slightly opened
B.throttled
C.fully opened
D.halfway opened

4.单项选择题The capacity of a centrifugal pump can be increased by the installation of a larger diameter impeller Another means of increasing the pump capacity is to ().

A.increase speed
B.increase the size of the cardent assembly
C.reduce wearing ring clearances
D.change the pump to a "close coupled" arrangement

5.单项选择题Which of the following forms of energy is demonstrated through the process of combustion?()

A.Chemical energy
B.Mechanical energy
C.Thermal energy
D.Electrical energy

6.单项选择题While inspecting the steering system at sea, you should check for ().

A.air bubbles in the sight glass
B.any leaks in the system
C.over-travel in the rudder angle indicator
D.lost motion in the rams

7.单项选择题Excessive air leakage into the suction side of a centrifugal pump would be indicated by which of the following operational problems?()

A.The pump delivers full capacity when started, but gradually slackens off toan abnormally low flow
B.The pump packing gland overheats after short operating periods
C.The motor over-current protective device continually shuts the pump down
D.Pounding noises can be heard at the pump suction chest

8.单项选择题Increasing the speed of a centrifugal pump will result in an increase in its capacity Another means of increasing the capacity of a centrifugal pump is to increase the ().

A.diameter of the discharge piping, with all other factors remaining the same
B.diameter of the suction piping, with all other factors remaining the same
C.width of the impeller only
D.diameter of the impeller

9.单项选择题If the discharge valves on a refrigeration compressor are leaking badly, the compressor should ().

A.run continuously
B.not start
C.have high discharge pressure
D.short cycle on the high pressure switch

10.单项选择题Which of the following terms could be applied to the simple definition the energy of motion?()

A.Electrical energy
B.Thermal energy
C.Potential energy
D.Kinetic energy