单项选择题To avoid impingement attack, care must be taken with the water () through the tubes of the heat exchangers.

A.temperature
B.velocity
C.density
D.viscosity


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1.单项选择题A non-return valve in the air delivery line near to the compressor must be ()type similar to the compressor discharge valve.

A.the low inertia
B.the high inertia
C.the low velocity
D.the high velocity

2.单项选择题A () in the air delivery line near to each compressor is essential.

A.butterfly valve
B.globe valve
C.gate valve
D.non-return valve

4.单项选择题Bad valves operation of the reciprocating air compressors can be detected by observation of ().

A.the discharge temperature low
B.the discharge temperature high
C.the discharge pressure rise
D.the inter-stage pressure low

5.单项选择题By far the greatest item of maintenance of the reciprocating air compressors concerns ().

A.the lubrication
B.the cooling
C.the moisture separation
D.the valves

6.单项选择题A compressor should never be stopped ().

A.without first cooling it
B.without first heating it
C.without first unloading it
D.without first loading it

8.单项选择题During compressors running the accumulated moisture in the separators must be ().

A.drained off
B.collected
C.sent to the crankcases
D.separated with oil

9.单项选择题By far the greatest use is for diesel engine starting using air pressure of 25 bar or more provided by ().

A.rotary compressors
B.reciprocating compressors
C.centrifugal compressors
D.screw compressors

10.单项选择题Compressed air is used on board ship for all the following purposes except ().

A.starting diesel engines
B.pneumatic control systems
C.pneumatic tools
D.supercharging air

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