单项选择题
When you adjust a thermostatic expansion valve, （）.
A.refrigerant must be bled off the sensing line before adjustments are made
B.all refrigerant must be pumped into the receiver before adjustments are made
C.time must be allowed for conditions to stabilize in the evaporator before further adjustments are made
D.all refrigerant must be routed through the dehydrator while changing the superheat setting
相关考题
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单项选择题
If a centrifugal pump were continually operated with the discharge valve closed, the （）.
A.motor controller overload would open
B.pump would eventually overheat
C.relief valve would continuously cycle open
D.motor would overheat -
单项选择题
A double suction centrifugal pump impeller has been installed in the reverse direction, and will （）.
A.have a greater head capacity
B.operate with increased impeller efficiency
C.discharge through the suction side of the pump casing
D.require more power to run the shaft -
单项选择题
Hydraulic machinery failures are commonly caused by misalignment of the system components and by （）.
A.hydraulic fluid contamination
B.excessive fluid friction
C.turbulent fluid flow
D.fluid pressure surges
