单项选择题
Which of the problems listed represents the major difficulty encountered with thermal expansion valve operation?（）
A.Lube oil passing through the system
B.Moisture or foreign matter collecting at the valve seat and orifice
C.Variable spring tension caused by the changing temperature
D.Frost on the liquid line
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相关考题
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单项选择题
Broken valve strips in an operating low pressure, air compressor will cause （）.
A.an immediate crankcase explosion
B.oil contamination in the compressed air
C.a decrease in compressor capacity
D.no immediate loss of the compressed air capacity -
单项选择题
Which of the listed operating conditions would have the greatest effect on the volumetric efficiency of an operating reciprocating air compressor?（）
A.The density of the air entering the compressor
B.The temperature of the air entering the compressor
C.The designed rotating speed of the compressor
D.A leaking head gasket -
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
