Module 37 · Purifiers

TST Engineering Services · E-Learning Recap

Marine Fuel & Lube Oil Purifiers

A high-value oral exam recap on purifier principles, bowl internals, interface control, throughput, faults, and practical operation. The new TST-branded nomogram image has been added into this infographic as a dedicated training section.

Fuel & Lube Oil Treatment Centrifugal Separation Troubleshooting & Orals

Focus areas

Gravity disc, interface, sealing water, disc stack efficiency, temperature, viscosity, throughput and fault diagnosis.

Exam value

Ideal for explaining what the purifier is doing physically, what happens when separation degrades, and what checks prove the machine is operating correctly.

Progress

0 of 6 sections marked complete

What this recap covers

This page is designed to look and feel like the Module 22 infographic layout you shared, but now tailored to purifiers. It also includes the new nomogram image in a dedicated section so the concept can be revised visually as well as theoretically.

Explain how density difference and centrifugal force separate heavy and light phases.
Describe the bowl, disc stack, sludge space, clean oil outlet and water seal/interface.
State what improves separation: heat, correct viscosity, steady feed and suitable throughput.
Identify symptoms of poor operation such as water carry-over, vibration, loss of seal, and dirty clean oil.
Use the nomogram as a training aid to discuss density, temperature, viscosity and indicative throughput.

Start recap Jump to nomogram

Navigation

Use the cards below to move between sections. Mark each section as complete as you revise.

1. Core principleWhy purifiers matter 2. Bowl internalsWhat each part does 3. Separation qualityWhat improves or worsens it 4. NomogramImage section added 5. Checks & faultsWhat to monitor 6. Oral answersHow to say it cleanly

0 / 6 sections complete

Section 1

A purifier is not just a spinning bowl

Purpose

A purifier protects engines by continuously removing water and suspended solids from fuel or lube oil. Under high rotational speed, heavier material is forced outward while the lighter cleaned oil remains closer to the centre and is discharged separately.

Why it matters

Good purification reduces wear, prevents corrosion, keeps injectors and pumps cleaner, protects bearings, and improves reliability. If the purifier performs badly, contamination reaches sensitive machinery.

Feed entersDirty oil enters the rotating bowl and is distributed through the disc stack.

Separation occursDensity difference under centrifugal force drives solids and water outward.

Clean oil leavesThe lighter phase moves toward the centre and exits via the clean oil outlet.

Sludge accumulatesHeavier solids collect near the bowl periphery until discharged or manually cleaned.

Oral exam angle

Do not stop at “it separates by centrifugal force”. Add what is being separated, why density difference matters, and how temperature and viscosity directly affect the result.

Section 2

Bowl internals and interface control

Disc stack

Creates many thin separation passages, shortens settling distance, and gives a far larger effective area for separation than an open bowl alone.

Heavy phase

Water and solids move toward the bowl outside. Solids remain in the sludge space; the heavier liquid phase is controlled by interface position.

Light phase

The cleaned oil remains nearer the centre and is led away through the paring disc or outlet arrangement.

Water seal / interface

The interface must be in the correct position. Too far in or out can cause oil loss, water carry-over, or poor purification. Gravity disc selection and seal water setup are key.

A purifier may spin at the correct speed yet still perform badly if the interface is wrong, the bowl is dirty, the feed is too cold, or the throughput is excessive.

Section 3

What improves or worsens separation?

Factor	Good practice	If incorrect
Temperature	Heat oil to reduce viscosity and improve flow through the disc stack.	Cold oil separates poorly; water and solids are more likely to pass through.
Viscosity	Operate at the maker’s recommended inlet viscosity range.	High viscosity reduces separation efficiency and often requires lower throughput.
Throughput	Feed at a realistic rate so residence time remains adequate.	Excess throughput shortens separation time and can overwhelm the bowl.
Bowl cleanliness	Maintain disc stack and sludge spaces in clean condition.	Fouling disrupts flow patterns and lowers efficiency.
Interface setting	Correct gravity disc / water seal positioning maintains stable separation.	Incorrect interface causes oil loss, water in clean oil or unstable operation.

Improves separation

Stable temperature, correct sealing water, clean internals, right throughput and proper gravity disc selection.

Degrades separation

Rapid load changes, excessive feed, incorrect heater control, air ingress, emulsions and neglected maintenance.

Typical evidence

Dirty sample glass, water alarms, sludge discharge abnormalities, rising differential pressure or downstream contamination.

Section 4

Purifier nomogram — image added to the infographic

TST branded marine purifier nomogram showing density, temperature, inlet viscosity and indicative throughput axes

TST-branded training nomogram added into the infographic. It is intended as a visual learning aid to help connect density, treatment temperature, inlet viscosity and indicative throughput. Final operational settings must always be checked against maker guidance.

How to use the nomogram

Mark the fuel density on the first axis.
Mark the treatment temperature on the second axis.
Mark the target inlet viscosity on the third axis.
Follow the guide line across to estimate an indicative purifier throughput.

Revision value

Helps explain why hotter oil usually separates more effectively.
Shows why more viscous or denser oils often need lower throughput.
Reinforces that throughput is not an isolated setting; it depends on oil condition.
Useful for discussing why one purifier setting cannot suit every oil condition.

Section 5

What to check — and what faults look like

Routine checks

Correct bowl speed and stable drive condition.
Heater outlet temperature and feed pressure in range.
Clean oil sample clear and free from water.
Sludge discharge timing and quantity as expected.
No abnormal vibration, noise, leakage or overheating.

Do not keep running blind

Water in clean oil: suspect bad interface, insufficient heat, emulsion, or internal leakage.
Vibration: suspect bowl contamination, poor assembly, worn bearings or imbalance.
Poor throughput: suspect fouled internals, restriction, low temperature or control issue.
Oil loss to sludge/water side: suspect incorrect gravity disc or wrong seal position.

Overhaul and post-overhaul proof

After overhaul, confirm correct bowl assembly, correct tightening, clean disc stack orientation, free movement of operating parts, leak-free operation, normal current draw, stable vibration behaviour and acceptable clean oil sample quality.

Section 6

Clean oral answers you can say out loud

Explain the purifier principle: “A purifier uses centrifugal force to separate phases of different density. Water and solids move outward, while the lighter cleaned oil remains nearer the centre and is discharged separately.”
Explain why heating matters: “Heating reduces oil viscosity, which improves mobility through the disc stack and makes water and solids easier to separate.”
Explain the disc stack: “The disc stack multiplies the effective separation area and reduces the settling distance, so separation becomes much more efficient.”
Explain a bad interface: “If the interface is wrongly positioned, the purifier may lose oil, pass water into the clean side, or become unstable even if bowl speed is correct.”
Explain throughput: “If throughput is too high, residence time is reduced and separation quality falls. Throughput must suit density, temperature and viscosity.”