-
When start a screw pump, the by pass valve should be ().
A . closed
B . opened fully
C . cracked open
D . partly ope
-
Which of the following pumps belongs to centrifugal pump?()
A . Reciprocating pump
B . Screw pump
C . Diffuser pump
D . Water-ring pum
-
Under rotary pumps are the gear, (), cam-and-piston and screw types.
A . reciprocating
B . diffuser
C . turbine
D . vane
-
One of the main differences between the various types of screw pumps is in the ().
A . stuffing box diameter
B . direction of rotation of the screws
C . pitch of the screws
D . type of driving gear
-
Which of the following pumps will build up a bursting pressure or stall their motors if the discharge valves are closed?() (1) gear (2) centrifugal (3) screw
A . (1)and(2)
B . (1),(2)and(3)
C . (1)and(3)
D . (2)and(3)
-
On a twin-screw,twin-rudder vessel,the most effective way to turn in your own water,with no way on,is to put().
A . one engine ahead and one engine astern,with full rudder
B . one engine ahead and one engine astern,with rudders amidships
C . both engines ahead,with full rudder
D . both engines astern,with full rudder
-
The function of a centrifugal pump double volute casing is to ().
A . reduce radial thrust to the impeller
B . double the liquid velocity through the pump when compared to a single volute
C . reduce hydraulic end thrust
D . provide the effect of multi-staging
-
A Cisco Catalyst switch can belong to how many VTP domains? ()
A . 1
B . 2
C . 1 to 1,005
D . 1 to 4,096
E . no limit
-
The amount of fluid delivered by a screw pump can be regulated by ().
A . throttling the pressure line
B . changing the speed of the rotor
C . either A or B
D . None of the above is tree
-
A gear pump belongs to () according to its working principle.
A . reciprocating pumps
B . positive displacement pumps
C . centrifugal pumps
D . centripetal pum
-
The gear and screw pumps are classified as ().
A . variable stroke pumps
B . multistage pumps
C . positive displacement pumps
D . triple-ported pum
-
A single-screw vessel going ahead tends to turn more rapidly to port because of propeller().
A . discharge current
B . suction current
C . sidewise force
D . thrust
-
A twin screw vessel,making headway with both engines turning ahead,will turn more readily to starboard if you().
A . reverse port engine,apply right rudder
B . reverse port engine,rudder amidships
C . reverse starboard engine,apply right rudder
D . reverse starboard engine,rudder amidshi
-
A twin screw craft being used to pick up a person who has fallen overboard from a vessel should approach if you().
A . reverse port engine, apply right rudder
B . reverse port engine,rudder amidships
C . reverse starboard engine, apply right rudder
D . revers starboard engine, rudder amidshi
-
While a ship with twin screw is making a turn, in order to prevent overload, the duty engineer should ()
A . reduce the fuel feeding of main engine of inner propeller
B . reduce the fuel feeding of main engine of outer propeller
C . firstly reduce the fuel of main engine of inner propeller, then reduce the fuel feeding of engine of outer propeller
D . reduce fuel feeding of two engines at the same time
-
The gear, screw, and vane pumps are all classified as ().
A . variable stroke pumps
B . multistage pumps
C . positive displacement pumps
D . triple-ported pum
-
The cleaned heated oil, after passing through the centrifuges, is to be pumped to a ().
A . settling tank
B . service tank
C . ballast tank
D . drain tank
-
A pump is said to have "negative suction head" when the pump is located ().
A . between the suction and discharge
B . below the liquid supply
C . above the liquid supply
D . any of the above
-
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump() (1) ejector (2) screw (3) centrifugal
A . (1)only
B . (1)and(2)
C . (1),(2)and(3)
D . (2)and(3)
-
To operate a centrifugal fire pump at reduced capacity, you should ().
A . readjust the relief valve
B . throttle the suction line
C . throttle the discharge valve
D . open the priming line
-
45 is belong to () at the stages in a person's life.
-
Which of the following belong to the characteristics of a company profile? ( )
-
“exchange among customers” belongs to e-business. ()A.正确B.错误
“exchange among customers” belongs to e-business. ()
A.正确
B.错误