308 EXAM

Question 1

What is the purpose of a switchboard?

Answer 1

It is to safely transfer electrical energy throughout the ship and at the correct voltage.

Question 2

Typically what is that starting current compared to the full load current?

Answer 2

5 - 8 times greater`

Question 3

State two reasons why a ship might require a shore supply

Answer 3

For maintenance purposes.
To prolong generator life hours.

Question 4

Name three supplies that an emergency generator might provide power to.

Answer 4

HPSW pumps
Smoke extractor fans
Firefighting equipment

Question 5

Explain why Duplex filters are fitted to a marine diesel engine.

Answer 5

There are always two fitted this is so one can keep the system operating while the other is free for maintenance.

Question 6

State 3 purposes for the use of lubricating oil

Answer 6

To prevent metal to metal contact.
To prevent heat.
To help protect the mechanisms.

Question 7

Describe preventative maintenance

Answer 7

preventative maintenance helps to prevent breakdowns, this will prolong the life expectancy of the parts and components. It is cost effective in the long run.

Question 8

What is air under pressure and state three applications it can be used for

Answer 8

Air under pressure is pressure stored under atmospheric pressure and is either used immediately or stored in tanks.
Used for -
* Tools
*Firefighting Equipment
*Mechanical Devices

Question 9

Name three different types of high pressure air compressors

Answer 9

Single and Multi
Screw
Centrifugal

Question 10

Where on a compressor would you typically find an intercooler and an after fan?

Answer 10

Intercoolers are placed between each compressor stage to cool the pressurized air.
After coolers are placed at the final stage to cool the pressurized air to room temperature.

Question 11

State three types of materials used in the pipework of a compressed air system

Answer 11

Black Pipe
Copper Pipe
Stainless Steal

Question 12

What is a service unit and what does it do?

Answer 12

*Lubricates
*Removes waste heat
*Regulates air pressure
*Filter out unwanted particles and moisture

Question 13

State five ways moisture can damage a compressed air system

Answer 13

*Erosion
*Corrosion
*Damage to
components
*Dilution to lubricants
*Waterlogging of valves
*Freezing under cold
conditions

Question 14

State the three types of air dryers

Answer 14

• Refrigeration
  *Absorption
  *Adsorption (desiccant)

Question 15

Describe one of the air dryers

Answer 15

Absorption uses a medium which will attract the moisture.
The medium bonds with the moisture and becomes a liquid.
This liquid is caught in a trap and must be disposed of and fresh medium must be added.

Question 16

State 4 daily checks to be conducted on a running diesel generator

Answer 16

*Temperature
*Pressure
*Air Leaks
*Fuel Leaks

Question 17

At what levels should a Fuel Header Tank Alarm sound for a running diesel generator for a low level and a high level?

Answer 17

25% LOW

98% HIGH

Question 18

State two factors affecting pressure drops and flow rates in HP Air systems

Answer 18

Pipes too short with unnecessary bends.
Pipes too narrow for purpose.