单项选择题
In order to distribute the side pressures over a wide area of the cylinder walls and liners, which of the listed types of pistons are used in modem low pressure air compressors?（）
A.Differential
B.Trunk
C.Barrel
D.Valve-in-head
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相关考题
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单项选择题
A cracked diaphragm in a thermostatic expansion valve will cause the valve to （）.
A.return to a neutral position
B.flood the evaporator
C.open
D.close -
单项选择题
If an air compressor is used to supply air primarily to the combustion control system and other pneumatic controllers, the entire system is known as the （）.
A.control air system
B.forced draft air system
C.supply air system
D.ships service air system -
单项选择题
When it is necessary to open a refrigeration system for repairs and the system will be open for more than a few minutes, the open ends of the system should be （）.
A.dehydrated
B.purged
C.plugged
D.evacuated
