网友您好， 请在下方输入框内输入要搜索的题目：
题目内容
（请给出正确答案）
单选题
Which of the following statements concerning butterfly valves is correct?（）
A
Special tools are required for lapping or grinding
B
It is impossible to throttle flow with a butterfly valve
C
To close the valve, it is only necessary to turn the handle a quarter of a turn
D
The butterfly valve should never be used in a freshwater system
参考答案
参考解析
解析：
暂无解析
更多 “单选题Which of the following statements concerning butterfly valves is correct?（）A Special tools are required for lapping or grindingB It is impossible to throttle flow with a butterfly valveC To close the valve, it is only necessary to turn the handle a quarter of a turnD The butterfly valve should never be used in a freshwater system” 相关考题
考题
The globe valve has a bulbous body, housing a valve seat and screw down plug or disc arranged at right angles to the axis of the pipeAccording to the above sentence, which of the following statements is not true?A.The profile of the valve is like a globeB.The valve seat is set into the bulbous bodyC.The plug or disc of the valve is made vertical to the axis of the pipeD.The valve seat is located at right side of the plug or disc
考题
All the following statements concerning the nature of language change is true except()
A language change is inevitableB language change is abruptC language change is universalD language change is extensive
考题
The valve on the discharge side of a cargo pump on a tank vessel will usually be a ______.A.butterfly valveB.spectacle valveC.check valveD.globe valve
考题
What is an advantage of a gate valve over a butterfly valve ________．A.Less frequent maintenanceB.Faster operationC.CheaperD.More compact
考题
Which of the following statements concerning intellectual property is wrong？（）A、Intellectual property is an intangible creationB、Intellectual property in ludes patents，trademarks，copyrights，etc.C、Intellectual property is a visible creationD、There are some agreement sconcerning intellectual property under the WTO
考题
Which of the following statements is TRUE concerning the po column of the vmstat command？（）A、 The sys is high when po is high.B、 The po represents the number of page steals.C、 The low values usually indicate insufficient paging space.D、 The low values usually indicate sufficient memory for the load.
考题
单选题Which of the following statements concerning energy is correct?（）A
Energy can be created or destroyedB
Energy may not be transformedC
The total quantity of energy in the universe is always the sameD
None of the above
考题
多选题Concerning the figure below, if a =b, which of the following statements must be true? (Indicate all such statements.)Ac=dBl and k are parallelCm and l are perpendicular
考题
单选题Which of the following statements describes the function of an air compressor intake filter?（）A
Protects against suction valve floatB
Provides a positive pressure on the air inlet valvesC
Prevents lubricating oil contamination of the compressed air supplyD
Protects against the damaging effects of airborne solid particles
考题
单选题Which of the following statements concerning cargo is correct?（）A
Cargoes are any type of goods transported by any type of shipsB
Cargoes are goods transported in bulkC
Cargoes usually include goods transported in bulk and in containersD
Cargoes are usually packaged in containers
考题
单选题Which one of following statement is not true concerning the suitable sites of the direct acting relief valve and the pilot operated relieve valve?（）A
the direct acting relief valve is used for controlling lower flows and pressureB
the pilot operated relief valve is used for controlling higher flows and pressureC
the pilot operated relief valve is used for controlling lower flows and pressureD
the controlling accuracy of direct acting relief valve is worse than that of the pilot operated relief valve
考题
单选题Unlike the globe valve, gate valves give full bore flow without change of direction, such a valve is not suitable to partially open operationAccording to the above sentence, which of the following statements is not true?（）A
The globe valve may be suitable for partially open operationB
The globe valve will give full bore flow with change of directionC
The gate valve gives full bore flow with change of directionD
The gate valve is suitable for full bore operation only
考题
单选题Which of the following statements is true concerning centrifugal pumps?（）A
They are particularly suited for pumping high viscosity fluidsB
They are started with the discharge valve openedC
The flow of liquid is developed by imparting energy due to the rotation of an impellerD
They are always mounted in a horizontal position
考题
单选题Which of the following statements is true concerning any evaporator?（）A
High conductivity of the distillate indicates distillate salinity is excessiveB
Increasing the absolute pressure of the shell will increase the distillers capacityC
Mesh separators are used in evaporators to filter the distillateD
Reducing the brine density will reduce the heat lost overboard
考题
单选题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 gasesB
A thermostatic expansion valve is used to control refrigerated space temperatureC
Refrigerant temperature in an evaporator is directly related to refrigerant pressureD
Dehydrators must be used continuously in a refrigeration system
考题
单选题Which of the following statements concerning fire-tube boilers is correct?（）A
Combustion gases flow through the tubesB
Flames impinge on the tubesC
Combustion occurs in the tubesD
Water flows through the tubes
考题
单选题Which of the following statements is true concerning the cetane number of diesel fuel?（）A
The cetane number affects the amount of injection lagB
The cetane number is an indication of the fuels viscosityC
Ignition lag is reduced with fuels having a high cetane numberD
The cetane number is of little significance in the combustion process
考题
单选题Which of the listed statements is correct concerning the starting of centrifugal pumps?（）A
They should always be started with the discharge valve closedB
They should always be started with the discharge valve openedC
A priming pump is always required to flood the impeller suctionD
They should always be started with the sealing line valves closed
考题
单选题Which of the following statements is correct concerning the “flash point ” of a liquid?（）A
It is lower than the ignition temperatureB
It is the temperature at which a substance will spontaneously igniteC
It is the temperature at which a substance, when ignited, will continue to bumD
It is the temperature at which the released vapors will fall within the explosive range
考题
单选题Which of the following statements is true concerning an oil cooler?（）A
The oil temperature is less than the cooling water temperatureB
The oil pressure is less than the cooling water pressureC
The oil pressure is greater than the cooling water pressureD
The oil flow control valve is always installed in the oil input line
考题
单选题Which of the following statements concerning fuel atomization in a diesel engine cylinder is correct?（）A
The greater the atomization, the greater the penetrationB
The greater the atomization, the less the penetrationC
The degree of atomization has nothing to do with the degree of penetrationD
Atomization and penetration are one and the same
考题
单选题Which of the listed statements is correct concerning refrigeration systems?（）A
Dehydrators must be used continuously in a refrigeration systemB
A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hoursC
A thermostatic expansion valve is used to control refrigerated space temperatureD
The liquid receiver functions to collect and remove non- condensable gases
考题
单选题During inspection of the machinery space, which of the following statements points to an unsatisfactory organization of the systematic maintenance?（）A
missing valve hand wheelsB
dirty tank topsC
a large number of temporary repairsD
All of the above
考题
单选题A butterfly valve consists basically of a disc pivoted across the bore of a ring body having the same radial dimensions as the pipe in which it is fitted.According to the above sentence, which of the following statements is not true?（）A
The diameter of a disc is the same as the outer diameter of the pipeB
We can infer that the valve is opened or closed by rotating the spindleC
A butterfly valve comprises a disc and a ring bodyD
The profile of the butterfly valve is a ring body
考题
单选题Which of the following statements is true concerning Halon 1301 fire extinguishing equipment?（）A
The agent is considered nontoxic at room temperature in low concentrationsB
The agent is less effective than carbon dioxideC
Halon primarily extinguishes the fire by coolingD
The agent cannot be used on electrical fires because it leaves a residue
考题
单选题Which of the following statements is correct concerning the viscosity of lubricating oil?（）A
Viscosity will increase as temperature increasesB
Viscosity is a measure of a fluid s internal resistance to flowC
Viscosity will decrease as temperature decreasesD
Viscosity is not dependent on temperature
考题
单选题The direct acting mechanical governor used with some small diesel engines, controls fuel flow to the engine by（）A
governor flyweight action on a pilot valve which controls fuel injectionB
governor flyweight motion acting on fuel controls through suitable linkageC
positioning a butterfly valve in the fuel delivery system positioningD
a servomotor piston attached to the fuel controls
热门标签
最新试卷