A.positive head
B.negative suction head
C.mechanical seal
D.vent valve attached to the casing at the top of the volute
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A.gate valve
B.globe valve
C.check valve
D.plug cock
A.At the designed operating temperature, the liquid refrigerant charge has changed to a vapor
B.The liquid refrigerant tends to collect at the bellows or diaphragm and reduces the valve sensitivity
C.The sensing bulb is empty of liquid refrigerant charge at the designed operating temperature
D.The sensing bulb is never emptied of liquid refrigerant under normal operating conditions
A.diaphragm type gage
B.pressure transducer
C.manometer
D.All of the above
A.reduce radial thrust to the impeller
B.double the liquid velocity through the pump when compared to a single volute
C.reduce hydraulic end thrust
D.provide the effect of multi-staging
A.dirt will cause corrosion of bearing
B.bearings will leak oil excessively
C.dirt is very abrasive when mixed with grease
D.grease will become inflammable
最新試題
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
A salinity indicator is used to determine the （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
The major source of chemical contaminants in hydraulic fluid is （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.