Copper Centrifugal Bilge Pump

I. Product Overview

Copper centrifugal bilge pumps are designed based on the centrifugal force transportation principle, using copper and copper alloys (brass, tin bronze, aluminum bronze, etc.) as the core material, providing efficient solutions for pumping and treating marine bilge water (mixed media containing oil, sediment, rust, etc.). The copper impeller and pump body, combined with anti-clogging structural design, integrate excellent seawater/oil corrosion resistance, solid particle wear resistance, and adaptability to ship swaying conditions, enabling stable operation in bilge water with chloride ions (Cl⁻ concentration 20,000ppm) and trace oil. They meet the strict certification requirements of the International Maritime Organization (IMO) International Convention for the Prevention of Pollution from Ships (MARPOL) and classification societies (CCS/ABS/DNV).

II. Core Materials and Performance Adaptation

1.Tin Bronze (ZCuSn10Pb1) — Preferred for Bilge Corrosion and Wear Resistance

Characteristics

Contains 10% tin and 1% lead, tensile strength ≥350MPa, corrosion rate <0.03mm/year in oily seawater (oil concentration ≤15ppm), solid particle (≤1mm sediment) wear resistance 5 times higher than cast iron, surface oxide film resists bilge water microbial corrosion (such as sulfate-reducing bacteria).

Thermal conductivity 150W/(m・K), effectively reducing pump body temperature rise from friction and extending mechanical seal life (temperature resistance ≤120℃).

Application Scenarios

Manufactures key components such as impellers and pump shafts, suitable for conventional bilge water (oil and sediment) pumping, resisting long-term bilge water electrochemical corrosion and impurity scouring.

2.Aluminum Bronze (ZCuAl10Fe3) — Benchmark for Impact Resistance and Explosion Protection

Characteristics

Contains 10% aluminum and 3% iron, tensile strength ≥600MPa, impact toughness ≥35J/cm², can withstand water hammer pressure (1.5 times working pressure) during rapid bilge water pumping, no sparks during friction (ignition energy ≥50mJ), complies with Ex nA IIC T4 explosion-proof grade, suitable for bilge environments with combustible gases.

In bilge water with fibrous impurities (such as rags and fishing net debris), entanglement resistance is 30% higher than tin bronze, impellers adopt open design (blade spacing ≥5mm) to reduce blockage.

Application Scenarios

Bilge pumps for oil tankers and chemical tankers, resisting trace corrosive cargo residues (such as petroleum coke and chemical residues in bilges), used with explosion-proof motors in flammable and explosive cargo holds.

3.Brass (H68 + Nickel Plating) — Lightweight Auxiliary Application

Characteristics

Contains 68% copper and 32% zinc, density 8.5g/cm³, 4% lower than tin bronze, cost reduced by 30%, salt spray resistance increased by 50% after surface nickel plating (thickness 5-8μm), suitable for non-load-bearing components (such as pump covers and nozzles).

Resistant to fresh water and low-salinity bilge water (Cl⁻≤10,000ppm), stable performance in bilge water with minor lubricating oil (viscosity ≤100cSt).

Application Scenarios

Auxiliary bilge pumps for small ships (such as fishing vessels and yachts), flow ≤50m³/h, adapting to bilge drainage needs of inland ships or offshore workboats.

III. Technical Advantages and Application Limitations

Core Technical Advantages

1. Anti-Clogging Design and Complex Media Adaptability

Impellers adopt large-channel open design (flow channel width ≥15mm), capable of passing ≤5mm solid particles, combined with anti-entanglement blades (rear angle ≥30°) to reduce fibrous impurity entanglement. In oily bilge water (oil content ≤300ppm), separation efficiency ≥90%, preventing oil film adhesion from affecting pump efficiency.

2. Corrosion Resistance and Marine Condition Adaptation

Tin bronze impellers have a service life of 10-15 years in bilge water (pH6-9), 4 times that of cast iron impellers. The pump body uses an elastic support structure (vibration amplitude ≤0.05mm), adapting to ship trim 15° and list 10°, ensuring seal leakage ≤10mL/h.

3. High-Efficiency Drainage and Compliance

Hydraulic efficiency reaches 70%-80%, 12% higher than traditional cast iron pumps, shortening bilge water emptying time for 100,000 DWT cargo ships by 15%. Certified by classification societies, complying with MARPOL Annex I oil content control requirements for bilge water discharge (≤15ppm), pump body materials do not chemically react with bilge water treatment agents (such as polyaluminum chloride).

Application Limitations

1. Strong Corrosion and High-Viscosity Restrictions

Prohibited from transporting bilge water with strong acids (pH<4) or alkalis (pH>10); brass pumps are prone to stress corrosion in ammonia (NH₃)-containing bilge water. When transporting oily sewage with viscosity >200cSt, preheat to viscosity ≤100cSt (otherwise efficiency decreases by 25%).

2. Cost and Weight Challenges

Tin bronze pumps cost 3-4 times more than cast iron, density 8.9g/cm³ is 3 times higher than aluminum alloy (e.g., 100mm diameter pump weighs about 28kg), requiring reinforced ship foundations during installation. Large-flow models (≥200m³/h) have 8%-10% higher energy consumption than stainless steel pumps.

3. Impurity Sensitivity and Maintenance Requirements

Sensitive to solid particles >5mm (such as bolts and rust blocks), mandatory basket filter configuration (aperture ≤10mm); otherwise, impeller wear rate increases to 0.08mm per thousand hours. Oily bilge water easily forms oil films on copper surfaces, requiring regular chemical cleaning (quarterly).

IV. Typical Application Scenarios

1. Conventional Bilge Drainage for Merchant Ships

Container Ships/Bulk Carriers: Tin bronze pumps drain engine room bilge water (containing lubricating oil and coolant), flow 80-150m³/h, head 20-40m, used with oil-water separators (SEP) for compliant discharge, meeting IMO MEPC.107(49) resolution requirements.

Cruise Ship Sanitary Bilges: Aluminum bronze pumps drain bilge water with domestic sewage (COD≤500mg/L), impellers electrolytically polished (Ra≤0.8μm) to prevent microbial adhesion, adapting to sanitary bilge systems.

2. Oil Tanker and Hazardous Cargo Bilges

Crude Oil Tanker Cargo Bilges: Aluminum bronze pumps drain bilge water with crude oil residues, anti-static design (pump body grounding resistance ≤1Ω) to prevent oil gas explosions, combined with steam tracing (temperature 60-80℃) to avoid high-viscosity crude oil solidification blocking flow channels.

Chemical Tanker Bilge Emergency: Duplex copper alloy pumps (aluminum bronze + tin bronze composite material) drain residual corrosive chemicals (such as methanol and styrene), requiring prior confirmation of material compatibility (e.g., nickel-containing aluminum bronze for styrene).

3. Special Ship Bilge Systems

LNG Ship Low-Temperature Bilges: Tin bronze pumps operate in -10℃ low-temperature bilge water, copper alloys maintain ≥90% mechanical properties at low temperatures, combined with fluororubber seals (temperature resistance -40℃~120℃) to prevent low-temperature leakage.

Research Vessel Bilge Sampling: Brass pumps serve as bilge water sampling pumps, flow 10-20m³/h, materials comply with ISO 16232-12 requirements for ship pollutant sampling to avoid sample contamination.

V. Usage and Maintenance Specifications

1. Bilge Water Condition Adaptation

Pretreatment Requirements:

Bilge water with solid particles must first pass through a grating filter (≥10mm); oily bilge water must confirm oil concentration (>15ppm requires prior oil-water separator treatment). When pH<6 or >9, add neutralizing agents to adjust to neutral.

Temperature Control:

When bilge water temperature >60℃, inspect mechanical seal cooling effect (recommended to configure external flushing lines, flow 8-12L/min) to avoid seal aging due to high temperature.

2. Maintenance Key Points

Daily Monitoring:

Record inlet and outlet pressure daily (deviation ≤±5%), bearing temperature (temperature rise ≤35℃), equipped with oil content sensors (accuracy ±5ppm), automatic alarm for abnormal bilge water oil content;

Check pump body vibration value weekly (threshold ≤2.5mm/s), stop for impeller dynamic balance inspection (residual unbalance ≤5g・mm) in case of abnormalities.

Regular Maintenance:

Clean the filter every voyage (replace the screen when pressure difference >0.1MPa);

Disassemble and inspect impeller wear semi-annually (blade thickness wear ≤1mm), remove pump cavity oil scale with trichloroethylene solution (soaking time ≤15 minutes);

Replace mechanical seals when leakage >15 drops/minute, replace seal O-rings quarterly in oily bilge water (material preferably perfluororubber FFKM).

3. Compliance Requirements

Products must pass classification society certification (such as CCS Rules for the Statutory Survey of Ships and Offshore Installations), providing copper alloy bilge water corrosion resistance test reports (ASTM G48 standard, no pitting after 72-hour immersion);

Bilge pump performance must comply with IMO MARPOL Annex I Regulation 15 requirements for bilge water discharge systems, pump displacement should ensure bilge water is pumped out within a reasonable time (e.g., bilge pump displacement ≥40m³/h for ships over 500 GT).