Dolphin-DB300
Hamworthy Dolphin-DB300 — Bilge, Ballast, Cooling Water, Fire, General Service.
Inspector Detail
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Common issues
- Wear ring/casing clearance increasing, reducing capacity and efficiency
- Mechanical seal leakage at the shaft penetration
- Impeller erosion or cavitation damage from entrained air, debris or poor suction conditions
- Bearing wear from misalignment, vibration or lubrication neglect
- Non-return or foot valve fouling, affecting priming and back-flow prevention
- Vibration from coupling misalignment or impeller imbalance
Inspection checklist
- Confirm the pump reaches rated capacity and pressure on test
- Check the mechanical seal for leakage
- Check bearing temperature and vibration levels
- Inspect coupling alignment
- Inspect impeller and wear rings for erosion or excess clearance at overhaul
- Verify suction and non-return valves operate and seal correctly
- Confirm remote/emergency start arrangements function, given this pump's multi-duty (bilge/fire/GS) role
- Check priming system operation
Service intervals
| Bearing lubrication | per maker's schedule, typically every 4000-6000 hours or annually |
| Mechanical seal inspection | annually |
| Wear ring clearance check | at major overhaul, typically every 2-3 years |
| Alignment check | annually or after any maintenance disturbing the unit |
| Remote/emergency start function test | monthly to quarterly, per the vessel's fire/bilge pump testing regime |
Typical wear limits
| Wear ring radial clearance | typically 0.3-0.6 mm when new for pumps of this bore class; commonly renewed at around double the new clearance - confirm against the maker's manual |
| Shaft deflection/run-out | typically within 0.05-0.10 mm - confirm against the maker's manual |
| Mechanical seal spring compression/face condition | condition-based renewal on visible leakage or scoring; no universal numeric limit |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Mechanical seal kit
- Wear rings
- Bearing set
- Coupling element
- Impeller (if renewable)
Safety
- This pump commonly serves essential bilge/fire duty - never isolate it without confirming an alternative means of bilge or fire pumping is available
- Rotating coupling must be properly guarded
- Casing is under pressure - fully depressurise before opening
- Casing and impeller are heavy items - use proper lifting arrangements at overhaul
Class survey
Given its bilge/fire/general service duty, this pump falls under SOLAS bilge pumping arrangements and Continuous Survey Machinery. Class typically wants documented evidence of periodic capacity/pressure testing and, where the pump serves fire main duty, records of the monthly or quarterly test runs required by flag/class.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Visual inspection of impeller surfaces for pitting, erosion, or mechanical damage; perform performance curve monitoring for flow/pressure degradation
Observe seal chamber for coolant/liquid weeping; monitor temperature at seal location; check for discoloration or mineral deposits indicating seal breakdown
Listen for abnormal grinding, squealing, or chattering sounds during operation; monitor bearing temperature using infrared thermometer; check for axial/radial movement
Monitor pump inlet pressure and suction line conditions; perform flow rate testing; check for vapor pockets or unusual vibration at pump inlet
Inspect external casing for pitting, rust bloom, or material loss; verify material certificate (Bronze, Duplex, Stainless Steel); measure wall thickness in critical areas
Type-general inspection and maintenance points for this equipment category — not model-specific.
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