The disc stack is one of the most important components inside a marine fuel oil purifier . It is responsible for increasing the separation efficiency by dividing the oil into thin layers. Without the disc stack, proper separation of water and sludge from fuel oil would not be possible.
What is a Disc Stack in a Purifier?
A disc stack is a set of closely spaced conical stainless steel discs arranged one above another inside the purifier bowl. These discs are mounted on a central distributor and rotate together with the bowl at very high speed.
The main purpose of the disc stack is to:
- increase separation area
- reduce settling distance
- improve purification efficiency
Construction of Disc Stack
The disc stack assembly consists of:
Conical discs
Thin stainless steel plates with small holes. These are arranged in a stack formation.
Distributor
Central part that distributes incoming oil evenly between discs.
Top disc
Holds the stack in position and ensures proper alignment.
Bowl body support
Supports the complete stack during high-speed rotation.
Each disc has a slight cone angle and small clearance between adjacent discs, forming many thin passages for oil flow.
Working Principle of Disc Stack
When the purifier rotates at high speed, centrifugal force acts on the oil mixture.
The oil enters the disc stack and flows between the small gaps of the discs.
Because the layers are very thin:
- heavier particles (water and sludge) quickly move outward
- lighter oil moves inward toward the center
Since the settling distance is very small, separation becomes very fast and efficient.
This is why a purifier with disc stack is much more effective than simple gravity settling.
Why Disc Stack Improves Separation
The disc stack:
- reduces separation time
- improves removal of fine particles
- improves fuel cleanliness
Without the disc stack, separation would be slow and inefficient, especially for heavy fuel oil.
Common Problems in Disc Stack
During operation, several issues can occur:
Sludge deposition
Dirt and sludge stick between discs, blocking passages.
Reduced separation efficiency
Blocked discs prevent proper flow, causing poor purification.
Unbalance and vibration
Improper assembly may cause vibration.
You can read more about disc stack working principle here.
Cleaning Procedure of Disc Stack (Step-by-Step)
Disc stack cleaning is done during purifier overhaul.
Step 1 – Stop and isolate purifier
Ensure purifier is fully stopped and isolated.
Step 2 – Open bowl assembly
Remove bowl hood carefully.
Step 3 – Remove disc stack
Lift disc stack assembly using proper tools.
Step 4 – Separate discs
Arrange discs in order. Do not mix sequence.
Step 5 – Wash discs
Clean using:
- diesel oil
- kerosene
- approved cleaning solution like purifier disc clean
Remove sludge and deposits gently.
Step 6 – Inspect discs
Check for:
- cracks
- bending
- corrosion
- wear
Replace damaged discs.
Step 7 – Dry and reassemble
Dry completely and reassemble correctly.
Step 8 – Balance and fit bowl
Ensure proper tightening and alignment before restarting.
Precautions During Cleaning
- Never use hard tools or hammer
- Do not scratch disc surfaces
- Keep discs in correct order
- Use gloves to avoid injury
- Follow manufacturer’s manual
Improper handling can damage discs and cause imbalance.
Practical Signs of Dirty Disc Stack
Engineers you may observe:
- poor separation
- water in clean oil
- frequent sludge discharge
- high vibration
These signs indicate the need for cleaning.