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單項選擇題

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

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單項選擇題

Adequate attention must be given to the water cooling system of the air compressors, for （） can cause condensation on the cylinder walls.

A.overcooling
B.poor cooling
C.overloading
D.unloading

單項選擇題

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

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