Alfa Laval S815-HFO-Purifier
Alfa Laval S815-HFO-Purifier high-speed disc-stack centrifugal separator for fuel/lube oil treatment, marine auxiliary, optimised for heavy fuel oil purification. Fuel oil capacity 4400 l/h, lube oil capacity 3520 l/h. Bowl diameter 395 mm, motor power 5.5 kW. Part of the S-series — the current generation marine separators with ALCAP control.
Inspector Detail
▸
Common issues
- Sludge and soot build-up on the disc stack from heavy fuel oil catalytic fines and asphaltenes, reducing separation efficiency
- Accelerated seal ring and O-ring wear from higher HFO operating temperature
- Gravity disc mismatch for the fuel's density/viscosity leading to poor water separation or oil carryover to sludge
- Sliding bowl bottom wear affecting bowl opening/closing timing
- Nozzle/valve erosion from catalytic fines abrasion
- Bearing wear/vibration in the bowl spindle from prolonged high-temperature operation
- Heater/preheater temperature control issues affecting viscosity at the separator inlet
Inspection checklist
- Check bowl body, disc stack, and top disc for cracks, pitting, erosion, or corrosion at each major overhaul
- Verify seal ring/O-ring condition and dimensions against maker's tolerance
- Confirm correct gravity disc is fitted for current HFO density/temperature
- Check preheater outlet temperature against the fuel's viscosity requirement
- Check operating/sealing water supply pressure and quality
- Inspect for erosion damage from catalytic fines on discs, nozzles, and bowl surfaces
- Check bowl balance and running vibration
- Verify sludge discharge frequency against fuel contamination level
Service intervals
| Seal rings / O-ring set | typically every 4,000-8,000 running hours or at bowl overhaul, often shorter than on MDO duty due to higher operating temperature - confirm against maker's manual |
| Bowl disc stack cleaning | every 250-1,000 hours depending on cat fines content and desludge interval |
| Gearbox oil change | typically every 4,000-8,000 hours or per maker's schedule |
| Major bowl overhaul / bearing replacement | typically every 8,000-16,000 hours - confirm against maker's manual |
| Preheater temperature/viscosity check | each watch during operation |
Typical wear limits
| Seal ring wear | replace when visibly hardened, cracked, or below maker's minimum thickness - no universal figure, check maker's manual |
| Disc/nozzle erosion from cat fines | any measurable pitting or thinning at nozzle bores is cause for renewal - inspect per maker's guidance, no universal figure |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Seal ring set for bowl
- O-ring kit for sliding bowl bottom
- Gravity disc set for expected HFO density range
- Bowl spindle bearings
- Friction lining / brake pads (if fitted)
- Sludge discharge valve seals
Safety
- High rotational energy stored in the bowl - never open before full stop and lock-out
- Hot HFO under pressure, typically preheated to around 90-98 C for separation - burn risk at sampling/cleaning points
- Sludge and operating water discharge under pressure
- Erosive catalytic fines in sludge/discharge lines
Class survey
Fuel oil purifiers are typically covered under the vessel's general machinery survey; for HFO service, surveyors may pay particular attention to cat fine removal effectiveness (linked to main engine liner wear trends) and to overhaul records matching the maker's recommended interval.
Components & Design
Component data being added…
Technical Data
🤖 Ask about this model
One free question — answered like a marine engineer. No account needed.
Common failures & inspection points
Paring disc, top disc, mud ports check for dull spots/wash-out; erosion depth >0.2 mm (bowl/cap) or >0.5 mm (other) = replacement.
Leaks at cover/bolted joints/mud outlet; gasket rings (EPDM) change every 6000–8000 h, original parts only.
Check vibration/noise; bearings change in pairs every 12000–16000 h, lubricate correctly; do not increase throughput during vibration.
Belts every 3000 h (tension per manufacturer), cracks/wear; coupling check for axial play (>0.5 mm = fault), corrosion.
Monitor current consumption nominal/actual; clean bowl during shutdown; check pre-filtration + lubrication; limit sludge volume.
Type-general inspection and maintenance points for this equipment category — not model-specific.
Suppliers & Spare Parts
Direct links to manufacturer, datasheet, spare-parts portal and dealers — request access below.
📄 Request sourcing links & documentsCases, daily reports, timesheets and AI troubleshooting in the OceanSphere Marine app — free for 14 days.
Start free trial →Find manufacturers, repair shops and spare-part dealers in the Maritime Network — our global company directory.
Maritime Network →