单选题The valve best suited for throttling gas or liquid flow in a pipeline is the().Agate valveBglobe valveCcheck valveDplug cock
单选题
The valve best suited for throttling gas or liquid flow in a pipeline is the().
A
gate valve
B
globe valve
C
check valve
D
plug cock
参考解析
解析:
暂无解析
相关考题:
The______is used to measure the volume of a liquid or gas through a pipeline within any given period of timeA.flow-meterB.viscometerC.micrometerD.feeler
To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the_______ .A.suction service valve as a vaporB.suction service valve as a liquidC.discharge service valve as a vaporD.charging valve as a liquid
Which of the problems listed could cause erosion of the expansion valve disks and seats?A.Overcharging the system with refrigerantB.Faulty compressor suction valveC.Failure of the high pressure cutoutD.Flash gas formed in the liquid line
The flash point of a liquid refers to the temperature ______.A.at which a liquid will give off inflammable(易燃的) vaporsB.at which a liquid will burn steadilyC.at which a liquid will explodeD.that a liquid must reach before it will flow readily
A fire of escaping liquefied flammable gas is best extinguished by ______.A.cooling the gas below the ignition pointB.cutting off the supply of oxygenC.stopping the flow of gasD.interrupting the chain reaction
单选题Each inert gas system gas main must have an automatic shut down valve at the outlet of the gas production plant. This valve must close automatically upon().Acargo pump failureBblower failureCdeck seal low water levelDlow inert gas temperature
单选题A fire of escaping liquefied flammable gas is best extinguished by().Acooling the gas below the ignition pointBcutting off the supply of oxygenCstopping the flow of gasDinterrupting the chain reaction
单选题Before liquid can flow into a pump, the air in the suction line must be () sufficiently to cause the liquid to flow into the suction chamber.AfilledBevacuatedCcompressedDcharged
单选题If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is ().Atoo much refrigerant in the systemBoil entrained in the refrigerantCless than a full charge of refrigerant in the systemDice crystals forming in the refrigerant
单选题Which of the following methods is used to prevent throttling of compressed air through the diesel engine air starting valves?()AHolding the valve open for a long periodBIncreasing the starting air pressure usedCOpening the stating air valve quicklyDReducing the starting air valve size
单选题A pressure drop through the refrigerant liquid line may cause ().Asolenoid valve to seizeBcompressor to huntCformation of flash gas in the liquid lineDexpansion valve to freeze open
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?()AThe globe valve may be suitable for partially open operationBThe globe valve will give full bore flow with change of directionCThe gate valve gives full bore flow with change of directionDThe gate valve is suitable for full bore operation only
单选题Which of the following statements is true concerning centrifugal pumps?()AThey are particularly suited for pumping high viscosity fluidsBThey are started with the discharge valve openedCThe flow of liquid is developed by imparting energy due to the rotation of an impellerDThey are always mounted in a horizontal position
单选题A gate valve installed in a pipeline should be ().Aused in either the fully dosed or fully opened positionBinstalled with the stem downCused for steam service onlyDused to throttle or regulate the flow of liquid
单选题The valve which is most suited for regulating the flow through a pipeline is a ()Agate valveBglobe valveCswing-check valveDplug-cock valve
单选题A liquid sight flow indicator in a refrigeration system is examined and gas bubbles are noted in motion with the fluid flowThis means ().Athe system is fully chargedBthere is air leaking in from the condenserCice crystals are forming in the refrigerantDthe system contains less than a full charge of refrigerant
单选题The flash point of a liquid refers to the temperature ()Aat which a liquid will give off inflammable vaporsBat which a liquid will burn steadilyCat which a liquid will explodeDthat a liquid must reach before it will flow readily
单选题The expansion valve on a Freon system controls the ().Asuperheat of the gas leaving the compressorBback pressure in the evaporatorCtemperature of the iceboxDsuperheat of the gas leaving the evaporator
单选题One cause of high head pressure occurring in a refrigeration system can be ().Ainsufficient cooling water flow to the condenserBa low refrigerant charge in the systemCthe liquid valve is open too muchDhigh evaporator superheat
单选题Moisture in the refrigerant may ().Afreeze on the expansion valve seat and reduce the flow of liquid refrigerantBemulsify the oil in the condenserCfreeze in the king valveDclog the oil trap
单选题To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the ()Asuction service valve as a vaporBsuction service valve as a liquidCdischarge service valve as a vaporDcharging valve as a liquid
单选题The thermostatic valve has a throttling action, that is to say the valve can()Astop the refrigerant from flowingBforce the refrigerant to flowCcause the refrigerant pressure to riseDcause the refrigerant pressure to fall
单选题While troubleshooting a refrigeration system for low head pressure, liquid refrigerant flooding back from the evaporator is determined to be the causeIt may be necessary to ().Achange the expansion valve adjustmentBreadjust the water regulating valve to increase the flow of waterCpurge air from the condenserDclean the waterside of the condenser
单选题The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to ().Aincrease the refrigerating effect, by decreasing the amount of flash gasBallow the refrigerant to enter the throttling device in a saturated conditionCincrease the refrigerating effect by increasing the amount of flash gasDminimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side
单选题Fire in an engine compartment is best extinguished with carbon dioxide gas (CO2) and by().Acompletely closing the compartmentBclosing the compartment except for the ventilatorsCleaving the compartment open to the airDincreasing the air flow to the compartment by blowers
单选题A pressure drop in the liquid line of a refrigeration system may cause()Athe solenoid valve to seizeBthe compressor to huntCflash gas to form in the liquid lineDthe expansion valve to freeze open