單項(xiàng)選擇題

An advantage of a helical gear pump over a simple gear pump is that the helical gear pump is capable of （）.

A.maintaining a steadier speed
B.delivering liquids over greater distances
C.operating for longer periods of time
D.producing a smoother discharge flow

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單項(xiàng)選擇題
The size of ball and roller bearings can be identified by the （）.
A.rolling member size
B.inner race cone width
C.manufacturers numerical code
D.outer ring width
單項(xiàng)選擇題
A centrifugal pump produces flow with a resulting discharge head by energy conversionIt is typical for the energy conversion to follow the order of （）.
A.mechanical energy to kinetic energy to potential energy
B.mechanical energy to potential energy to kinetic energy
C.potential energy to mechanical energy to kinetic energy
D.kinetic energy to mechanical energy to potential energy
單項(xiàng)選擇題
If an operating bilge pump is developing good vacuum, but is unable to discharge any water, which of the following problems is the most probable cause?（）
A.The wearing rings are excessively worn
B.The suction strainer is clogged
C.The discharge valve is clogged
D.The shaft is worn
單項(xiàng)選擇題
The sudden reduction of pressure occurring within the crankcase of a refrigeration compressor during starting causes the （）.
A.sudden evaporation of wax crystals in the lubricant
B.sudden evaporation of entrapped air in the lubricant
C.release of refrigerant from the oil/refrigerant mixture
D.release of dissolved lubricant from the refrigerant
單項(xiàng)選擇題
One of the consequences in continuing to operate a centrifugal bilge pump with the discharge valve closed, is that the （）.
A.motor overload will open
B.relief valve will open
C.pump will overheat
D.motor will overheat
單項(xiàng)選擇題
Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?（）
A.The liquid receiver functions to collect and remove non-condensable gases
B.A thermostatic expansion valve is used to control refrigerated space temperature
C.Refrigerant temperature in an evaporator is directly related to refrigerant pressure
D.Dehydrators must be used continuously in a refrigeration system
單項(xiàng)選擇題
The basic function of the centrifugal pump impeller is to （）.
A.directly increase the pressure of the liquid being pumped
B.directly increase the velocity of the liquid being pumped
C.convert the potential energy of the liquid to kinetic energy
D.separate air from the liquid being pumped
單項(xiàng)選擇題
Excessive oil foaming in the crankcase of a refrigeration compressor can result in （）.
A.overheated compressor bearings
B.excess lube oil viscosity
C.carbon deposits on the compressor piston rings
D.wax crystals forming in the lubricant
單項(xiàng)選擇題
The centrifugal pump component responsible for converting the mechanical energy of the liquid being pumped, to that of kinetic energy is the （）.
A.electric motor
B.volute
C.impeller
D.diffusion nozzle
單項(xiàng)選擇題
In a refrigeration system, foaming of the crankcase oil may cause the （）.
A.expansion valve to overfeed
B.compressor to knock
C.water regulating valve to fail
D.crankcase drains to plug

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An advantage of a helical gear pump over a simple gear pump is that the helical gear pump is capable of （）.

你可能感興趣的試題

The size of ball and roller bearings can be identified by the （）.

A centrifugal pump produces flow with a resulting discharge head by energy conversionIt is typical for the energy conversion to follow the order of （）.

If an operating bilge pump is developing good vacuum, but is unable to discharge any water, which of the following problems is the most probable cause?（）

The sudden reduction of pressure occurring within the crankcase of a refrigeration compressor during starting causes the （）.

One of the consequences in continuing to operate a centrifugal bilge pump with the discharge valve closed, is that the （）.

Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?（）

The basic function of the centrifugal pump impeller is to （）.

Excessive oil foaming in the crankcase of a refrigeration compressor can result in （）.

The centrifugal pump component responsible for converting the mechanical energy of the liquid being pumped, to that of kinetic energy is the （）.

In a refrigeration system, foaming of the crankcase oil may cause the （）.