Tank Contents

Question 1

What do we have to indicate level in storage tanks?

Answer 1

Sight glass
Dip tape
Transducers

Question 2

What components are needed to make a level pressure indication?

Answer 2

• One differential pressure indicator
• One power supply/transmitter unit
• Remote indication panel
• Decca ISIS/MCASS/MaSS interface
• The pipework, together with the associated measurement pots and the isolation valves necessary to the pressure sensor

Question 3

What are the 4 methods for installing level sensors to tanks?

Answer 3

• open tank
• closed tank (dry leg)
• closed tank (wet leg)
• closed tank (top access only)

Question 4

Explain a closed tank wet leg

Answer 4

A wet leg system is one which the low pressure pipe is filled with the liquid being measured and maintained at a level above the maximum fill level of the tank. This is achieved by fitting a small topping up tank incorporating a filler cap or plug to enable the level to be maintained. The topping up tank is arranged so that the surplus liquid added will flow back into the main tank.

Question 5

How do you carry out an earth bonding test?

Answer 5

1. Carry out an inspection of the earth bonding cable
2. Earth bonding cable should be in good condition, tightly secured, undamaged and free from corrosion
3. Establish a good earth between 2 points of the motor
4. Connect one of the test meter leads between the good earth and the earth bonding cable connected to the ships structure.
5. Maximum acceptable reading less than 0.1 ohm

Question 7

How do you carry out an IR test on a 3 phase AC induction motor

Answer 7

1. Ensure motor starter is disconnected from phases of the motor
2. Establish a good earth between 2 points on the casing of the motor
3. Connect one of the test meter leads between the good earth and the 1st phase of the motor and take a reading
4. Repeat process for phase 2 and 3
5. IR between phases can be taken however on a star wound motor a direct short will be indicated on the test meter therefore phase to phase readings cannot be taken.
6. The maximum acceptable reading is 1 Mohm

Question 8

What planned maintenance is carried out on storage tanks?

Answer 8

1. Conduct ER and IR checks
2. Check system components:
   - examine float switches
   - transmitter and transducers
   - local and remote indication
   - overheating and deterioration of components
   - cable glands
3. Set to work