Centrifugal pumps have what advantage（s）over reciprocating pumps ________．A.They are less expensiveB.They are smaller for equivalent pumping abilityC.They pump more cargo in less timeD.All of the above
Centrifugal pumps have what advantage（s）over reciprocating pumps ________．
A.They are less expensive
B.They are smaller for equivalent pumping ability
C.They pump more cargo in less time
D.All of the above
相关考题：
What is the function of wearing rings found on some centrifugal pumps ________．A.Absorb erosion of high velocity discharge streamB.Seal pump shaft against entry of airC.Isolate the outlet side from the inlet sideD.Dampen the turbulent discharge flow
What is a requirement for remote manual shutdown stations for internal combustion engine driven cargo pumps on tank barges ________．A.They must be conspicuously markedB.They must be located at least 10 feet from the engineC.There must be at least two such shutdown devicesD.The valve rods shall be fitted with stuffing boxes
What is an advantage of a gate valve over a butterfly valve ________．A.Less frequent maintenanceB.Faster operationC.CheaperD.More compact
What is an advantage of diesel over steam turbine propulsion ________．A.Less fuel consumption per SHPB.Diesel fuel costs less than bunker C or its equivalentC.Less routine maintenance requiredD.Less weight per SHP
单选题Mechanical lubricators for diesel engine cylinders are usually small reciprocating pumps which are （）.Aoperated manually once an hourBoperated until the engine has startedCplaced into operation only at maximum loadDadjustable to meet lubrication requirements
单选题What is a function of the wearing rings used in most centrifugal pumps?（）AAbsorb erosion of high velocity discharge streamBSeal pump shaft against entry of airCIsolate the discharge side from the suction sideDDampen the turbulent discharge flow
单选题Which of the following statements represents the advantage of rotary pumps as compared to reciprocating pumps?（）AThe high discharge pressure of the rotary pumps permits a larger volume of fluid per unit time than the reciprocating pumpBRotary pumps are capable of pumping more fluid than reciprocating pumps of the same weightCRotary pumps occupy only one-half the space of reciprocating pumpsDRotary pumps eliminate discharge slippage of the pumped liquid, while this does not hold true for a reciprocating pump
单选题Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? （） (1) reciprocating (2) rotary (3) centrifugalA（1）onlyB（1）and（2）C（1），（2）and（3）D（2）and（3）
单选题The pumps employed on board ship can be divided into two main categories ie（） pumps and centrifugal pumps.AgearBnonpositive displacementCpositive displacementDrotary
单选题Air chambers are usually fitted to reciprocating pumps in order to （）.Aincrease discharge pressureBincrease suction vacuumCdevelop pulsation flowDkeep a steady rate of flow
单选题What is a characteristic of all centrifugal cargo pumps? （）AThey are self-primingBDecreasing the speed of rotation will decrease the discharge pressureCOpening the discharge valve wider will increase the discharge pressureDAll of the above
单选题A reciprocating pump belongs to （） according to its working principle.Ainjector pumpsBpositive displacement pumpsCcentrifugal pumpDcentripetal pumps
单选题Centrifugal pumps have what advantage(s) over reciprocating pumps?（）.AThey are less expensiveBThey are smaller for equivalent pumping abilityCThey pump more cargo in less timeDAll of the above
单选题What is an advantage of diesel over steam turbine propulsion? （）ALess fuel consumption per SHPBDiesel fuel costs less than bunker C or its equivalentCLess routine maintenance requiredDLess weight per SHP
单选题Under centrifugal pumps are the volute, diffuser, mixed-flow, axial flow and （） or regenerative types.AreciprocatingBhydraulicCturbineDvane
单选题机舱人员应启动机舱里的消防泵。（）AEngine room persons should stop their pumps in machinery space.BEngine room persons should start their pumps in machinery space.CEngine room persons should start their pumps in officer’s cabin.DEngine room persons should start their pumps on boat deck.
单选题Lube oil pumps taking suction from the sump of most small marine engines are usually （）.Aof the diaphragm typeBof the centrifugal typeCof the positive displacement typeDindependently driven by electric motors
单选题The injection may be delayed, （）the pumps are in good order, if the fuel lines to the injection valves have not been cleared of air.AbecauseBthoughCsinceDuntil
单选题When installed for bilge pumping or ballast duty, centrifugal pumps require a （） to remove air from the suction pipe.Aair chamberBhead lankCprimerDprime mover
单选题Which of the following pumps belongs to centrifugal pump?（）APiston pumpBScrew pumpCDiffuser pumpDWater-ring pump
单选题Which of the materials listed is used as the dynamic seal material on mechanical seals installed on most centrifugal pumps used in water service?（）ACopperBCopper and carbonCCarbonDBronze
单选题The advantage of a centrifugal pump as compared with a reciprocating pump is that （）.Adischarge is continuousBit has no internal valvesCupon accidental closing of discharge valve, excessive pressure will not build upDall of the above are true
单选题Centrifugal pumps, however, can be designed with a number of impellers （） to attain a large amount of liquid.Ain seriesBin parallelCassembledDtogether
单选题Which of the following statements concerning the lubrication of diesel propulsion engines used in vessels over 300 gross tons is most accurate?（）ALubrication systems using engine driven lube oil pumps do not require any additional independent arrangement when such arrangements have been proven reliableBThe use of engine driven pre-lube pumps is permitted on vessels with propulsion systems developing less than 500 shaft horsepowerCWhen forced lubrication is used for propulsion engines, one independently driven stand-by pumps is to be provided in addition to the necessary pumps for normal operationDLubrication systems where two oil coolers are fitted require a minimum of two temperature control devices which may be actuated by similar sensors
单选题Fuel oil transfer systems used onboard diesel propelled vessels are required to have （）.Atwo fuel oil transfer pumps provided where one is to be independent of the main engineBtwo fuel oil transfer pumps, with a combined capacity exceeding the maximum consumption of the main engineCengine driven transfer pumps and only used in constant speed applicationsDthe capacity of the engine driven pump exceed the consumption rate of the engine to which it is attached