Set 20 MEK Motor

1. Use of Halon as fire extinguishing medium has been discontinued because________________
It is highly toxic
It is expensive
It has high Ozone depleting potential
It leads to acid rains

2. The purpose of an air cooler in a supercharging system is to
Reduce temperature of supercharged air in order to condense and remove maximum possible moisture from the air prior entry to the engine
Reduce the temperature of the supercharged air in order to increase the density & also to cool down below dew point to remove moisture from air prior entry to the engine
Cool supercharged air to increase its density such that the dew point is not reached to avoid entry of moisture into the engine
Cool supercharged air to increase it???s density and also to keep the peak temperature and exhaust gas temperature within limits

3. In order for microbiological growths to thrive in a fuel tank it is necessary for
high temperatures to exist
low temperatures to exist
small amounts of water to be present
large amounts of water to be present

4. In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low-alloy steels because
the beveled edges of the intake valves provide forself-centering during seating
intake valves utilize stellite-coated valve seat insertswhich reduce wear
the volume of air passing through intake valves is less than the volume of air passing through exhaust valves
intake valves are less affected to the corrosive action of exhaust gases

5. Why is it essential to renew turbocharger bearings after a preset number of hours of running even if the bearings are in seemingly perfect condition?
Because they are prone to failure due to prolonged exposure to high temperature conditions.
Because they are subject to cyclic loading and are prone to failure due to metal fatigue.
It is not essential to renew if condition monitoring suggests perfect condition.
Lube oil contamination is bound to occur and affect the condition of the bearings.

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Correct answers: