A.vary their speed according to temperature and load
B.start and come up to speed before air compression begins
C.change speed according to overload demands
D.reduce compressed air charge density
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A.radiation
B.conduction
C.convection
D.condo-radiation
A.used in either the fully dosed or fully opened position
B.installed with the stem down
C.used for steam service only
D.used to throttle or regulate the flow of liquid
A.Radiation
B.Conduction
C.Natural convection
D.All of the above
A.A gate valve
B.A globe valve
C.Any check valve
D.Any needle valve
A.a shortage of compressor oil
B.warm food in the refrigerator
C.excessive condenser cooling water
D.a shortage of refrigerant
最新試題
Which of the listed pumps is NOT a positive displacement pump?（）
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
The usual symptoms of cavitation in a centrifugal pump is （）.
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）
When the steering gear is in operation, you should （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.