SJ-20F
The MKK SJ-20F is an 11 kW disc‑stack centrifugal fuel oil purifier that removes water, sludge and solid particles from marine diesel or heavy fuel oil, delivering clean fuel to the engine.
Inspector Detail
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Common issues
- Bowl vibration from disc-stack fouling or an incorrect gravity disc selection
- Sludge discharge malfunction (partial ejection) causing carryover into the clean oil
- Friction clutch slip on startup, delaying the bowl reaching full speed
- Bowl spindle bearing wear producing noise/heat at the top bearing
- Seal ring wear shifting the oil/water interface and contaminating clean oil
- Operating water solenoid valve fouling, upsetting discharge water timing
- Feed pump or preheater malfunction upsetting inlet temperature/viscosity
Inspection checklist
- Check the bowl for vibration and unusual noise at running speed
- Inspect the disc stack, distributor and bowl body for sludge buildup/scale at teardown
- Check seal rings, O-rings and gaskets for wear or hardening
- Verify the gravity disc size matches the fuel density in use
- Check friction clutch/gear coupling wear and lubrication
- Confirm sludge discharge timing/intervals and inspect discharge ports for erosion
- Inspect the bowl spindle and bearings for play; replace if noise or heat is present
- Check inlet/outlet flow, pressure and temperature against nameplate values
Service intervals
| Bowl disc stack cleaning | typically every 2,000-4,000h or per observed fouling rate |
| Seal rings, O-rings, gaskets | renew at every bowl overhaul, roughly 4,000-8,000h |
| Bowl spindle bearings (top/bottom) | typically 8,000-10,000h, per manufacturer manual |
| Friction clutch lining | condition-based, checked at each major overhaul |
| Gear case oil/grease | per manufacturer schedule, typically annually |
Typical wear limits
| Seal ring wear | renew when visibly grooved/hardened or when clean-oil contamination appears - no universal dimensional figure applies, follow the bowl manual |
| Bowl spindle bearing radial play | renew when play is perceptible by hand or per the manufacturer's go/no-go gauge - confirm against the manufacturer's manual |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Bowl gasket/O-ring set
- Seal ring set
- Bowl spindle bearings (top and bottom)
- Friction clutch lining/pads
- Sludge discharge valve seals
- Gravity disc set (assorted sizes)
Safety
- The bowl rotates at several thousand RPM - never open the separator before it has fully stopped
- Incorrect bowl assembly or torque can cause imbalance and violent vibration or bowl disintegration
- Hot fuel oil under pressure at feed/discharge connections
- Sludge tank and discharge lines carry hot oil/water mixture - scald risk
Class survey
Fuel oil separators normally fall within Continuous Survey Machinery scope; surveyors typically check overspeed/vibration trip function, sludge tank and oily-water handling arrangements, and that overhaul records match the planned maintenance system's stated intervals.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Service & Maintenance
Cat fine removal critical — reduce throughput for better separation. Monitor outlet fuel quality.
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