Which of the following are components of a mechanical seal? （）
(1) stationary ring
(2) rotational ring
(3) packing
(4)spring
A.(1), (2) and (3)
B.(1), (2) and (4)
C.(2), (3) and (4)
D.None of the above
您可能感興趣的試卷
你可能感興趣的試題
A.variable stroke pumps
B.multistage pumps
C.positive displacement pumps
D.triple-ported pumps
A.mixed-flow pump
B.axial-flow pump
C.centrifugal pump
D.displacement pump
A.on top cover
B.on sides of bowl
C.in drain line on the discs
D.on the discs
A.oil
B.sea water
C.refrigerant
D.fresh water
A.a flash generator
B.a flash evaporator
C.a vacuum boiling evaporator
D.a boiler
最新試題
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
Which of the following statements is correct concerning heat transfer?（）
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.