Q- It is a known fact that centrifugal pumps require priming for pumping liquids , as they cannot handle air and will lose suction due to air entry . But on the other hand T/Cs use centrifugal compressors for supercharging . Which of the following do you think makes a centrifugal compressors to pump air and behave differently than the centrifugal pumps?
A.Presence of air cooler
B.Presence of Labyrinth seal
C.High speed of rotation , very fine internal clearences and large impeller diameters
D.Difference in principle of operation
Q- Modern marine turbochargers use a ___________ type of compressor
Q- What do you mean by surge limit of a turbocharger?
A. Characteristic curve of a turbocharger
B. Portion of compressor characteristic curve which lies on the left side of the point of maximum pressure
C. A line joining all the points of maximum pressure on compressor characteristic curves , drawn at various speeds of operation
D. Maximum rpm limit of T/C above which surging will start
Q- With full load on the main engine, the RPM for the turbocharger is too low. What may cause this?
A The diffuser ring is damaged.
B Exhaust temperatures on the main engine are too high.
C Dirty nozzle ring.
D The lubricating oil pump is malfunctioning.
Q- A partial opening of which of the following kinds of valves can lead to wire -drawing of its seat?
D.Full bore angle valve
Q- Scale formation in a fresh water generator evaporator can lead to ____________________
A.Impaired heat transfer
C.Increased shell temperature
D.All of the above