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
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The major source of chemical contaminants in hydraulic fluid is （）.
Thermostatic expansion valves can be adjusted for （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
A pressure drop through the refrigerant liquid line may cause （）.