Separators

Question 1

Describe the liquid flow in a separator?

Answer 1

• Oil is led by the distributor towards the periphery of the bowl.
• Centrifugal force lets the oil rise through the channels formed by the disc stack where it is evenly distributed.
• Oil is continuously separated from water and as sludge as it flows towards the bowl centre, rising upwards through the disc stack, entering the pairing chamber and pumped by the pairing disc out.
• Water rises along the outside of the disc stack as it has a greater density than the oil, passing over the gravity disc and leaving the bowl.
• Heavy impurities like sludge are collected in the bowl periphery and discharged at regular intervals.

Question 2

Describe the water seal in purification.

Answer 2

To prevent oil from leaving the water outlet, a water seal must be provided.
- The bowl is filled with water before oil is supplied.
- When oil is supplied the oil will force the water towards the periphery creating an interface.
- Said interface can be changed by the size of the gravity disc.

Question 3

Describe the displacement of oil in a separator?

Answer 3

To avoid oil loss at sludge discharge, displacement water is fed into the bowl.
- Prior to discharge, the oil feed is stopped and displacement water added.
- This changes the balance in the bowl and the interface is moved inwards up the disc, increasing the water volume in the sludge space.
- When the sludge discharge takes place the sludge and water are both discharged.
- Sludge discharge is done while the displacement water still flows, and therefore a new water seal will establish afterwards.

Question 4

What is the gravity disc?

Answer 4

The gravity disc determines the position of the oil interface. A larger one will move the interface towards the bowl periphery while a smaller one will move it closer to the bowl centre. It also determines the free water level in the bowl.

Question 5

Describe the difference between a clarifier and purifier.

Answer 5

A clarifier does not separate the water from the sludge, and discharges it as one.
- The gravity disc is replaced by a clarifier disc which seals off the water outlet.
- No interface is necessary as no water seal is required.

Question 6

Describe the sludge discharge function.

Answer 6

• Sludge is discharged through ports in the bowl wall.
• Said ports are usually covered by the sliding bowl bottom, and the sliding piston is pushed downwards by water against a sealing ring to allow for discharge.
• Water is drained off through holes in the bowl body.

Question 7

State two factors that have an influence on the separating process.

Answer 7

• Input temperature
• Density

Question 8

Give two reasons for a purifier not attaining full running speed.

Answer 8

• Heavy sludge deposits on the bowl.
• Issues with the motor.
• Worn bearings

Question 9

Consequences of too large a gravity disc.

Answer 9

• Water carry over with fuel.
• Loss in water seal.
• Seal interface to close to the bowl edge.

Question 10

Consequences if too small a gravity disc.

Answer 10

• Slow oil purification rate.
• Solid matter carry over.
• Poor sludge removal.