Introduction
Sometimes the purifier runs smoothly with no alarms, but still the fuel quality is bad. You may notice cloudy oil, water in service tank, or sludge building up quickly. This means the purifier is running, but separation is not happening properly.
This condition is called poor separation efficiency.
It is a very common problem onboard ships and usually happens because of small operating mistakes rather than major mechanical faults. The good news is that most issues can be fixed easily if you know what to check.
Let’s go through it the same way an engineer would troubleshoot during a watch.
Most Common Reasons for Poor Separation (and How to Fix Them)
1. Fuel Temperature Too Low
This is the number one reason.
If fuel is not heated properly, it becomes thick. Thick oil cannot separate from water and sludge easily. The purifier needs hot, thin oil to work efficiently.
What happens:
Separation becomes slow
Water droplets stay mixed with oil
2. Wrong Gravity Disc Size
If gravity disc is not correct for the fuel density, the interface shifts. When the interface is wrong, separation becomes unstable.
What happens:
Oil loss or water carryover
Unstable discharge
Fix:
Check fuel density from bunker report
Refer maker’s chart
Fit correct disc
Small adjustment, big difference.
3. Throughput Too High (Overloading)
Sometimes we try to push more oil to clean faster. But purifier needs time to separate.
If flow is too high, oil leaves the bowl before proper separation.
What happens:
Poor cleaning
Water and sludge carryover
Fix:
Reduce feed rate
Operate at maker’s rated capacity
Remember, slower and steady is better than fast and dirty.
4. Dirty Disc Stack
Disc stack is the heart of separation. If sludge blocks the small gaps between discs, oil cannot flow properly.
What happens:
Less separation area
Low efficiency
Fix:
Stop purifier
Open bowl
Clean disc stack thoroughly
After cleaning, you’ll immediately see better discharge clarity.
5. Sludge Space Full
If sludge is not discharged properly, sludge space becomes overloaded. This reduces the effective separation area.
What happens:
Poor separation
Frequent vibration
Fix:
Check desludging interval
Ensure sludge ports are not blocked
Carry out manual cleaning if required
6. Low Bowl Speed (RPM)
Centrifugal force depends on speed. If speed is low, separation force becomes weak.
What happens:
Heavy particles don’t move outward
Poor purification
Fix:
Check motor condition
Check belt/clutch (if fitted)
Ensure purifier reaches full speed before oil entry
Low speed = weak separation.
7. Insufficient Sealing or Operating Water
Improper water supply disturbs internal working of the bowl.
What happens:
Interface unstable
Separation affected
Fix:
Check water pressure
Clean filters
Ensure proper supply
Simple Troubleshooting Order
If purifier is not separating properly, follow this order:
First check temperature
Then reduce throughput
Then check gravity disc
Then inspect discharge
Then plan cleaning
Most of the time the problem gets solved before opening the bowl.