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Marine Diaphragm Bilge Pump

Date:2025-07-16Views:

Marine Diaphragm Bilge Pump

I. Product Overview

Marine diaphragm bilge pumps are the "flexible conveying experts" of ship bilge water removal systems, designed specifically to handle complex bilge water containing large amounts of impurities, fibers, and oil. Through the reciprocating deformation of rubber diaphragms to create volume changes, they achieve negative pressure water suction and pressurized drainage, fundamentally solving the problems of easy clogging and rapid wear in traditional impeller pumps. Constructed with cast iron (HT250), aluminum alloy (ADC12), or stainless steel (316L) as the main material, and diaphragms made of oil-resistant nitrile rubber (NBR) or fluororubber (FKM), they are compatible with bilge water (containing sediment, wood chips, emulsified oil) with a solid content ≤8% and viscosity ≤500cSt. The pump body undergoes anti-corrosion treatment and enhanced sealing, with a service life of ≥8 years in -10℃~60℃ environments. It meets IMO International Convention for the Prevention of Pollution from Ships (MARPOL Annex I) and bilge pump certification requirements of classification societies such as RS, LR, ABS, and CCS, widely used in bilge drainage systems of oil tankers, chemical tankers, fishing boats, and other vessel types.

II. Core Technologies and Material Characteristics

1.Material Selection and Performance

Material Type

Characteristic Advantages

Typical Application Scenarios

Cast Iron (HT250)

Low cost, high structural strength (tensile strength ≥250MPa); suitable for freshwater bilge water with 少量 impurities; ideal for inland cargo ships (working pressure 0.6-1.6MPa).

Bilge drainage systems of inland cargo ships and barges

Aluminum Alloy (ADC12)

Lightweight (density 2.7g/cm³) with good heat dissipation; suitable for portable mobile drainage; ideal for coastal fishing boats (pressure 0.6-1.2MPa).

Emergency drainage systems for fishing holds and decks of coastal fishing boats

Stainless Steel (316L)

Contains 17% Cr, 12% Ni, 2.5% Mo; resistant to seawater erosion and chemical sewage corrosion; suitable for ocean-going oil tankers (pressure 1.0-2.0MPa).

Bilge water removal systems of ocean-going oil tankers and chemical tankers

2.Key Technical Parameters

Flow range: 10-100m³/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 drainage from bilge to overboard (including filter and elbow resistance losses)

Medium compatibility: Capable of conveying bilge water containing sediment (particle size ≤10mm), oil (concentration ≤10%), short fibers (length ≤50mm), with temperatures ranging from -10℃ to 60℃ and pH 4-10

Self-priming performance: Self-priming height ≥5m, priming time ≤40 seconds (for clean water), capable of direct startup without priming devices

Anti-clogging capability: Flow channel diameter ≥100mm, with flexible diaphragm deformation enabling "wrapping" of impurities for passage. Achieves 98% passage rate for plastic bags and fishing net fragments, with a clogging rate 90% lower than centrifugal pump

3.Safety and Anti-Pollution Design

Explosion-proof certification: Motors adopt Ex d IIB T4 Gb explosion-proof grade, suitable for Zone 2 hazardous areas near engine rooms and cargo oil tanks to prevent oil and gas explosions

Dry running protection: Equipped with liquid level sensors, automatically shutting down after bilge water is pumped dry to avoid diaphragm damage from dry friction (dry running tolerance ≤5 minutes)

Anti-backflow structure: A check valve installed at the outlet prevents seawater backflow into the bilge after shutdown, ensuring drainage results are maintained

III. Technical Advantages and Innovative Design

1. Complex Media Handling Capacity

Dual-diaphragm linkage structure: Adopts main and auxiliary dual-diaphragm alternating design, increasing flow by 60% compared to single-diaphragm pumps with pressure fluctuation ≤±0.05MPa for more stable drainage.

Flexible flow channel: Diaphragms and pump chambers form a fully enclosed flexible flow channel without metal friction pairs, enabling conveyance of sewage containing sharp impurities (e.g., broken glass) without wear, extending service life 3 times compared to impeller pumps.

Automatic exhaust function: Integrates a gas-liquid separation chamber to automatically discharge air when inhaled, avoiding "air binding" and ensuring stable operation in bilge water with high foam content (e.g., containing fire-fighting foam).

2. Wear and Corrosion Resistance Enhancement

Diaphragm material upgrade: Fluororubber (FKM) diaphragms undergo vulcanization strengthening, improving oil and temperature resistance (-20℃~120℃) by 50% compared to ordinary nitrile rubber, with a service life of 8000 hours.

Stainless steel flow channel polishing: 316L flow components undergo electrolytic polishing (Ra≤0.8μm) to reduce oil adhesion, showing no rust after 5000 hours of immersion in 3% salt spray environment, suitable for long-term ocean-going use.

Cast iron pump anti-corrosion coating: Inner walls of HT250 pump bodies are sprayed with a polyurea coating (0.3mm thick) with a Shore D hardness of 80, improving sediment erosion resistance by 60% compared to ordinary cast iron.

3. Ship Operating Condition Adaptability

Modular design: Wear parts such as diaphragms and valve plates use snap-on installation, reducing replacement time to ≤30 minutes, 50% shorter than traditional diaphragm pumps.

Tilt resistance: Flow attenuation ≤5% under ship heel ±15° and trim ±10°, ensuring uninterrupted drainage in severe sea conditions.

Energy-efficient drive: Uses variable frequency motors (1.5-15kW), with flow steplessly adjustable within 30%-100% range, reducing no-load power consumption by 40% compared to fixed-frequency pumps.

IV. Typical Application Scenarios

1. Routine Bilge Drainage

Cargo hold drainage: 10,000 gross ton dry cargo ships use stainless steel diaphragm bilge pumps (flow 30-50m³/h, pressure 1.2MPa) to extract bilge water containing wood chips and packing straps, discharging it overboard through 100mm diameter pipelines with 300 hours of continuous operation without clogging.

Fishing hold dredging: Trawler boats use portable aluminum alloy diaphragm pumps (flow 10-15m³/h, pressure 1.0MPa) to clean fishing hold water containing fish scales, bone fragments, and fishing net fibers. Weighing only 45kg, they can be carried to different holds by 2 people.

2. Special Sewage Removal

Oil tanker slop tank drainage: 30,000 gross ton oil tankers use explosion-proof stainless steel diaphragm pumps (flow 40-60m³/h, pressure 1.6MPa) to convey bilge water containing 5% emulsified oil to oil-water separators, with diaphragms meeting 1000-hour oil resistance without damage.

Chemical tanker tank washing drainage: Chemical tankers use fluororubber diaphragm pumps (flow 20-30m³/h, pressure 1.5MPa) after tank washing to convey sewage containing trace acids and alkalis (pH 5-9) to treatment devices, with pump bodies showing no corrosion or leakage.

3. Emergency Drainage Scenarios

Post-collision water rescue: When ships collide and bilge water enters through hull damage, stainless steel diaphragm pumps (flow 50-80m³/h, pressure 2.0MPa) drain water through temporary hoses, cooperating with equipment to slow sinking and buy rescue time.

Post-fire water treatment: After cargo hold fires, cast iron diaphragm pumps (flow 20-30m³/h, pressure 1.2MPa) extract mixtures of fire-fighting foam and water, with diaphragms showing no swelling or rupture due to chemical resistance.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Bilge water type: Cast iron/aluminum alloy pumps for freshwater + low impurities; stainless steel pumps for oil-contaminated water and seawater; 316L + fluororubber diaphragm models for chemical sewage

Flow calculation: Configure 1.5 times the maximum bilge water accumulation rate; e.g., a hold accumulating 10m³/h requires flow ≥15m³/h

Pressure requirements: 0.6-1.2MPa for short-distance drainage (bilge to overboard); 1.2-2.0MPa for long-distance or high-rise cabin drainage

2. Maintenance Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.1MPa), diaphragm leakage (≤5 drops/minute), and motor temperature (≤80℃) every 400 hours

Regular maintenance: Replace diaphragms (nitrile rubber 8000 hours/fluororubber 12000 hours) and valve plates every 2000 hours; clean inlet filters

Medium switching maintenance: Flush pump chambers with clean water for 10 minutes before switching from sewage to oil-contaminated water to avoid impurity mixing and pipeline blockage

3. Compliance Inspection

Annual classification society inspection focusing on verifying impurity-containing media conveyance capacity (flow attenuation ≤10% with 8% solid content) and explosion-proof performance

Meets MARPOL Annex I requirements for ship bilge water discharge, with oil content ≤15ppm when used with oil-water separators

VI. Compliance and Certification

International standards: Complies with ISO 15749 marine diaphragm pump performance standards and IMO MARPOL Annex I bilge water management regulations

Classification society certifications: Obtained type approval for diaphragm bilge pumps from RS, LR, ABS, and CCS (including 1000-hour solid-containing sewage operation tests)

Environmental requirements: Leak-free sealing at pump and pipeline connections (meeting ISO 18797 standards) to prevent bilge water leakage and marine pollution


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