單項選擇題Which of the listed types steam traps operates on the principle that hot water flashes to steam when its vapor pressure is rapidly reduced?（）

A.Ball float
B.Thermostatic
C.Bimetallic
D.Impulse


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1.單項選擇題On all vessels equipped with refrigeration units of over 20 cubic foot capacity, （）.

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

2.單項選擇題The emergency bilge suction valve is typically used （）.

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

3.單項選擇題Short cycling of a refrigeration compressor refers to （）.

A.frequently grounding out
B.frequently starting and stopping
C.running too fast
D.running too slow

4.單項選擇題When a flash-type evaporator is to be secured for an extended period of time, the entire unit should be drained, cleaned, and （）.

A.completely filled with saltwater
B.filled with de-scaling compound
C.tightly closed to exclude air
D.vented to the atmosphere

5.單項選擇題Condensate must be drained periodically from the air compressor receivers to prevent （）.

A.second stage cylinder lockup
B.oil sump contamination
C.faulty operation of pneumatic valves
D.corrosion of air receiver baffles