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
Centrifugal pumps, however, can be designed with a number of impellers （） to attain a large amount of liquid.
A
in series
B
in parallel
C
assembled
D
together
参考答案
参考解析
解析：
暂无解析
更多 “单选题Centrifugal pumps, however, can be designed with a number of impellers （） to attain a large amount of liquid.A in seriesB in parallelC assembledD together” 相关考题
考题
If a centrifugal pump is driven by a constant speed electric motor and produces a discharge pressure less than designed, the cause is probably ______.A.excessive pump speedB.excessive suction headC.worn wearing ringsD.gross pump misalignment
考题
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
考题
The TTL field was originally designed to hold a time stamp, which was decremented by each visited router. The datagram was ( ) when the value became zero. However, for this scheme, all the machines must have synchronized clocks and must know how long it takes for a datagram to go from one machine to another. Today, this field is used mostly to control the ( ) number of hops (routers) visited by the datagram. When a source host sends the datagram, it (请作答此空) a number in this field. Each router that processes the datagram decrements this number by 1. If this value, after being decremented, is zero, the router discards the datagram.This field is needed because routing tables in the Internet can become corrupted.A datagram may travel between two or more routers for a long time without ever getting delivered to the ( ).This field limits the ( ) of a datagram.A.controls
B.transmits
C.stores
D.receives
考题
The TTL field was originally designed to hold a time stamp, which was decremented by each visited router. The datagram was ( ) when the value became zero. However, for this scheme, all the machines must have synchronized clocks and must know how long it takes for a datagram to go from one machine to another. Today, this field is used mostly to control the ( ) number of hops (routers) visited by the datagram. When a source host sends the datagram, it ( ) a number in this field. Each router that processes the datagram decrements this number by 1. If this value, after being decremented, is zero, the router discards the datagram.This field is needed because routing tables in the Internet can become corrupted.A datagram may travel between two or more routers for a long time without ever getting delivered to the (请作答此空).This field limits the ( ) of a datagram.A.switch
B.router
C.source host
D.destination host
考题
单选题The various pumps and lines are （） to some extent so that each pump can act as an alternative for another.A
interlockedB
interconnectedC
interferedD
interacted
考题
单选题Shaft sealing in a centrifugal pump can be effected by （）.A
the mechanical sealB
packed stuffing boxesC
either A or BD
neither A nor B
考题
单选题What is a function of the wearing rings used in most centrifugal pumps?（）A
Absorb erosion of high velocity discharge streamB
Seal pump shaft against entry of airC
Isolate the discharge side from the suction sideD
Dampen the turbulent discharge flow
考题
单选题The pumps employed on board ship can be divided into two main categories ie（） pumps and centrifugal pumps.A
gearB
nonpositive displacementC
positive displacementD
rotary
考题
单选题Positive displacement, helical gear pumps are well suited for pumping oil because （）A
stuffing boxes eliminate the leakage problems usually associated with other gear pumpsB
it is not necessary to closely maintain design clearances with this pumpC
they are essentially self-priming and produce a high suction liftD
these pumps are designed with extreme tooth angled
考题
单选题The minimum number and capacity of bilge pumps and fire pumps and their distributing within the ship is governed by （）.A
Classification Society RulesB
National requirementsC
The IMO International Convention for the Safety of Life at SeaD
All of the above
考题
单选题What is a characteristic of all centrifugal cargo pumps? （）A
They are self-primingB
Decreasing the speed of rotation will decrease the discharge pressureC
Opening the discharge valve wider will increase the discharge pressureD
All of the above
考题
单选题Most pump manufacturers recommended that the discharge piping for centrifugal pumps be （）.A
one size larger than the pump discharge nozzleB
the same size as the pump discharge nozzleC
one size smaller than the pump discharge nozzleD
installed with a short radius elbow at the pump
考题
单选题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
考题
单选题For optimum results, centrifugal purification of heavy fuel oil should be accomplished with the fuel at the lowest practicable（）A
throughputB
additive percentC
cetane numberD
TBN number
考题
单选题A centrifugal impeller consists of a number of vanes curving （） from the direction of rotation.A
backwardsB
forwardsC
upwardD
downwards
考题
单选题Under centrifugal pumps are the volute, diffuser, mixed-flow, axial flow and （） or regenerative types.A
reciprocatingB
hydraulicC
turbineD
vane
考题
单选题The engine has one or two group of fuel pumps, depending upon （）.A
the number of fuel valvesB
the number of cylindersC
the speed of engineD
the power of engine
考题
单选题If a centrifugal pump is driven by a constant speed electric motor and produces a discharge pressure less than designed, the cause is probably（）.A
excessive pump speedB
excessive suction headC
worn wearing ringsD
gross pump misalignment
考题
单选题Lube oil pumps taking suction from the sump of most small marine engines are usually （）.A
of the diaphragm typeB
of the centrifugal typeC
of the positive displacement typeD
independently driven by electric motors
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When installed for bilge pumping or ballast duty, centrifugal pumps require a （） to remove air from the suction pipe.A
air chamberB
head lankC
primerD
prime mover
考题
单选题Most pump manufacturers recommend that the suction piping dimension for centrifugal pumps be （）.A
one size smaller than the pump suction nozzleB
the same size as the pump suction nozzleC
one size larger than the pump suction nozzleD
installed with a short radius elbow at the pump
考题
单选题Which of the following pumps belongs to centrifugal pump?（）A
Piston pumpB
Screw pumpC
Diffuser pumpD
Water-ring pump
考题
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?（）A
CopperB
Copper and carbonC
CarbonD
Bronze
考题
单选题Centrifugal pumps can be designed with a number of impellers （） to attain a high final delivery pressure.A
in seriesB
in parallelC
either A or BD
None of the above is tree
考题
单选题Centrifugal pumps are popular because they are very simple in construction,and produce smooth, constant, （） discharge.A
non-pulsatingB
pulsatingC
positiveD
non-positive
考题
单选题A centrifugal pump can’t supply water after startingYou should check （）.A
priming waterB
power supplyC
packing glandD
bearing lubrication
热门标签
最新试卷
