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MEK Motor e pariksha online questions for class 4 engineers

1) Which of the following statements is true, about slow speed engines?
A.A scavenge fire can lead to a crankcase explosion
B.A scavenge fire can lead to deformation of diaphragm plate
C.A scavenge fire can lead to damage to tie rods.
D.All of the above.

2) When using low sulfur fuel oil for Emission Control Areas (ECA???S), ideally the TBN of the cylinder oil used should be:
A.Lower than normal
B.Higher than normal
C.Same as normal
D.Same as normal if the feed is kept higher

3) For a two stroke engine two o-rings are provided on the liner. The function of the top o-ring is to ___________ and function of the lower o-ring is to ____________
A.Seal jacket cooling water, act as secondary seal in case 1st o-ring leaks
B.Seal jacket cooling water, Seal scavenge air
C.Seal scavenge air, Seal Jacket cooling water
D.Seal combustion gases, Seal jacket cooling water

4) The coating which is provided on the valve stem of exhaust valves of modern marine diesel engines is of:

5) If the combustion control system of an automatically fired auxiliary boiler fails to sustain burner ignition after a normal shutdown, you should check for a/an
A.faulty photocell detector
B.low steam pressure
C.high voltage on the ignition electrode air damper

6) 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

7) A large, low-speed, main propulsion diesel engine uses sea water to directly cool the
A.cylinder heads
B.exhaust valves
C.scavenging air

8) Exhaust Grouping is required in case of ______________ turbocharging in order to _____________________
A.Constant pressure , prevents shockwave generation
B.Pulse pressure , prevent interference with scavenging of other cylinders
C.Constant pressure, prevent interference with scavenging of other cylinders
D.Pulse pressure , prevents shockwave generation

9) Function of a de-superheater is to :
A.Protect superheater from overheat
B.Control superheater steam outlet temperature
C.Increase the efficiency of the boiler
D.Reduce steam temperature for auxiliary uses after steam superheater

10) Which of the following statements is false?
A.Oxidation of lubricant leads to decrease in its viscosity
B.Formation of oxidation acids, sulfuric acid leads to depletion of TBN of lubricant
C.Contamination with water will lead to decrease in the load carrying capacity of a lubricant .
D.Build up of insolubles will lead to increase in viscosity of a lubricant

11) Which of the following conditions is responsible for the fuel oil to atomize when using a steam atomizer in anauxiliary boiler?
A.Expansion of the steam in the furnace.
B.Expansion of the steam in the whirling chamber.
C.Expansion of the steam in the orifice plate.
D.All of the above.

12) After prolonged operation, jerk type fuel pumps wear on the top edge of plunger and edges of spill ports and helix due to erosion by high pressure fuel as it spills. This wear would result in _________________
A.Late start of injection and early end of injection
B.Early start of injection and late end of injection
C.Early start of injection and early end of injection
D.Late start of injection and late end of injection

13) 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

14) If an operating auxiliary boiler has a water pH reading of 7, you should
A.bottom blow the boiler
B.treat the water with caustic soda
C.treat the water with chemical scavengers
D.reduce the water alkalinity to recommended readings

15) Even if there is an oil mist concentration inside a crankcase, and there is also a hot spot, crankcase explosion will only take place when_________________
A.The hot spot provides the ignition temperature for the oil mist concentration
B.When the oil mist - air mixture is in the flammable range
C.Both A and B
D.None of the abov

16) In case of 2-stroke marine diesel engines, the top part of the liner forming the combustion chamber experiences very high pressure induced mechanical stresses as well as high thermal stresses. Which of the following is a correctly designed liner for catering both the above stresses ?
A.Thick top portion with jacket cooling to take care of both the high mechanical and thermal stresses
B.Thick top portion to take care of high mechanical stresses while bore cooling to reduce thermal gradients
C.Thin top portion to reduce thermal gradients and hence thermal stresses while supporting ribs to take care of mechanical stresses
D.Thick top portion to take care of high mechanical stresses with jacket cooling combined with allowance for thermal expansion to minimize the thermal stresses

17) Which of these fuel oil impurities can cause maximum abrasive damage?
C.Catalytic fines

18) Steam temperature control for the ESD boiler is achieved by :
A.Fitting a de-superheater between 1st & 2nd passes of superheater
B.Fitting an attemperator between 1st & 2nd passes of superheater
C.Bypassing the superheater
D.Gas dampers in boiler uptake

19) Irregular circumferential wear of liner due to diminishing neutralizing capacity of cylinder oil away from lubricating holes is known as:
A.Micro seizure
D.Clover leafing

20) Which of the following is a reasonable statement about water washing of turbine side of a T/C ?
A.It leads to thermal shock and reduces the life of the T/C
B.It leads to thermal shock and not so effective as solid washing
C.If properly carried out keeping rpm , load ,temperature limits & other factors into account , it is quite safe and more effective than solid washing
D.It should never be carried out as most of the engine manufacturers recommend against the same

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