Marine Centrifugal Bilge Pump

I. Product Overview

Marine centrifugal bilge pumps are key equipment in ship bilge water removal systems, designed specifically to collect and discharge mixed liquids such as bilge water, leaked seawater, oily sewage, and small amounts of impurities. They ensure ship stability and prevent equipment damage from cabin water accumulation. Constructed with cast iron (HT250) or bronze alloy (ZCuSn5Pb5Zn5) as the main material, they generate negative pressure through high-speed rotation of centrifugal impellers to self-prime bilge water, pressurize it, and discharge it overboard or to oil-water separators. The pump body undergoes anti-corrosion treatment, operating stably in -10℃~60℃ environments with a salt spray corrosion resistance life of ≥8 years. It meets IMO Guidelines for the Design of Ship Bilge Water Systems (MSC.1/Circ.1476) and bilge equipment certification requirements of classification societies such as RS, LR, ABS, and CCS. As essential equipment for ships over 500 gross tons, it is widely used in inland and coastal vessels including cargo ships, passenger ships, and fishing boats.

II. Core Technologies and Material Characteristics

1.Material Selection and Performance

2.Key Technical Parameters

Flow range: 5-150m³/h, suitable for ships of 500-20,000 gross tons (e.g., 5000 gross ton ships require flow ≥20m³/h)

Head coverage: 8-30m, meeting pressure requirements for discharge from bilge to overboard (including pipeline elbows and filter resistance losses)

Medium compatibility: Capable of conveying oil-containing water (oil content ≤5%), freshwater, low-salinity seawater (sediment content ≤2%), and mixed liquids with temperature ≤50℃

Self-priming performance: Self-priming height ≥5m, priming time ≤60 seconds, no manual priming required, suitable for low-level bilge water (water depth ≥50mm)

Anti-clogging capability: Can pass solid particles ≤10mm in diameter (e.g., sediment, wood chips), reducing clogging rates by 60% compared to ordinary centrifugal pumps

3.Safety and Anti-Clogging Design

Liquid level linkage control: Equipped with float level switches, automatically starting when bilge water level ≥150mm and stopping when ≤50mm to prevent motor burnout from dry running

Dual filtration protection: Inlet fitted with coarse filters (10mm aperture) + fine filters (3mm aperture) to intercept large particles, cooperating with semi-open impeller designs to reduce fiber entanglement

Lightweight structure: 35% lighter than stainless steel bilge pumps of the same specification, with a single unit weight ≤300kg, suitable for hoisting installation in narrow engine rooms

III. Technical Advantages and Innovative Design

1. Efficient Liquid Discharge Capacity

Wide-channel impeller: Uses large-diameter semi-open impellers with a flow channel cross-sectional area 25% larger than closed impellers, achieving volumetric efficiency ≥85% in air-containing water (air content ≤10%) and avoiding air binding.

Self-priming enhancement design: Pump casings integrate guide vanes and return holes, shortening priming time to 40 seconds (30% faster than traditional centrifugal pumps) to ensure rapid discharge of low-level water.

2. Corrosion Resistance and Wear Resistance Enhancement

Bronze alloy flow components: Impellers and pump covers are integrally cast from bronze, showing no significant pitting after 3000-hour immersion in 3% salt water, with excellent resistance to oil adhesion in bilge water, extending cleaning intervals to 3 months.

Cast iron pump anti-corrosion treatment: HT250 pump inner walls are sprayed with ceramic coatings (thickness ≥0.2mm) with hardness up to HV800, improving sediment wear resistance by 50% and suitable for inland sandy waters.

3. Adaptability to Ship Operating Conditions

Tilt resistance: Pump units feature low-center-of-gravity designs, maintaining stable water absorption with flow attenuation ≤5% under ship heel ±15° and trim ±10°.

Low-noise operation: Impellers undergo dynamic and static balance correction, with operating noise ≤75dB (at 1 meter), cooperating with rubber shock pads to meet passenger cabin noise requirements.

IV. Typical Application Scenarios

1. Routine Bilge Discharge

Cargo hold water removal: When cargo holds of bulk carriers leak during navigation, cast iron centrifugal bilge pumps (flow 30-50m³/h, head 20m) automatically start, discharging 50m³ of water within 2 hours to prevent cargo damage from moisture.

Engine room sewage discharge: When coastal passenger ship engine rooms leak from cooling water pipes, bronze alloy bilge pumps (flow 20-30m³/h) deliver oily water to oil-water separators, achieving compliant discharge after treatment (oil content ≤15ppm).

2. Emergency Discharge Operations

Minor grounding drainage: When ships sustain minor bottom damage from grounding, bronze bilge pumps (flow 50-80m³/h) operate continuously with a drainage rate 1.5 times the water inflow rate, buying time for repairs.

Heavy rainwater removal: During heavy rain, inland cargo ships use bilge pumps (flow 15-25m³/h) with deck drains to discharge 30m³ of rainwater within 1 hour, preventing stability issues from water accumulation.

3. Special Ship Adaptation

Fishing boat hold drainage: After cleaning fishing holds of offshore fishing boats, bronze bilge pumps (flow 10-20m³/h) discharge water containing fish blood and scales, resisting fishy odor adhesion and extending cleaning intervals to 30 days.

Yacht bilge systems: Luxury yachts use silent bilge pumps (flow 5-10m³/h) with operating noise ≤65dB, maintaining dry bilges through automatic level control without manual operation.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Ship navigation area: Cast iron pumps for inland ships; bronze alloy pumps for coastal areas/oily bilge water

Drainage requirements: Configure 1.2 times the maximum hourly bilge water volume; e.g., 100m³ daily accumulation requires flow ≥5m³/h

Installation conditions: Compact models (length ≤1.0m) for space-constrained scenarios (e.g., yachts); anti-clogging models for high-impurity waters

2. Maintenance Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.1MPa), bearing temperature (≤70℃), and seal leakage (≤2mL/h) every 600 hours

Regular maintenance: Clean dual filters monthly; replace mechanical seals (oil-resistant nitrile rubber) every 1500 hours; inspect impeller wear (allowable radial clearance ≤0.3mm)

Anti-corrosion maintenance: Clean bronze pumps with citric acid solution every 6 months to remove oxide layers; spray anti-rust paint on cast iron pumps annually to extend service life

3. Compliance Inspection

Annual classification society inspection, focusing on verification of self-priming performance (priming time ≤60 seconds) and compatibility with oil-water separators

Meets IMO Annex I requirements for bilge water discharge (oil content ≤15ppm), prohibiting direct discharge of untreated oily water

VI. Compliance and Certification

International standards: Complies with IMO MSC.1/Circ.1476 bilge water system guidelines and ISO 80369 ship pipeline connection standards

Classification society certifications: Obtained bilge pump type approval from RS, LR, ABS, and CCS (including 1000-hour oily water operation tests)

Environmental requirements: When used with oil-water separators, discharged water meets MARPOL Annex I discharge standards