Marine Diaphragm Sewage Pump

I. Product Overview

Marine diaphragm sewage pumps are the "flexible sewage discharge core" of ship sewage treatment systems, designed specifically to convey domestic sewage, kitchen wastewater, and engine room oily sewage containing high concentrations of impurities, fibers, and oil. Through the reciprocating movement of rubber diaphragms to create volume changes, they achieve negative pressure suction and pressurized discharge, fundamentally solving the frequent failure problems of traditional impeller pumps caused by impurity entanglement and wear. Constructed with cast iron (HT250), stainless steel (316L), or engineering plastic (PP + glass fiber) as the main material, and diaphragms made of oil-resistant nitrile rubber (NBR) or perfluoroelastomer (FFKM), they are compatible with complex sewage media (containing feces, food residues, emulsified oil) with a solid content ≤10% and viscosity ≤1000cSt. The pump body undergoes anti-corrosion treatment and enhanced sealing, with a service life of ≥8 years in -10℃~70℃ environments. It meets IMO International Convention for the Prevention of Pollution from Ships (MARPOL Annex IV) and sewage pump certification requirements of classification societies such as RS, LR, ABS, and CCS, widely used in sewage treatment systems of passenger ships, oil tankers, fishing boats, and other vessel types.

II. Core Technologies and Material Characteristics

1.Material Selection and Performance

2.Key Technical Parameters

Flow range: 5-50m³/h, suitable for ships with 100-1000 personnel (e.g., 500-person passenger ships require flow ≥20m³/h)

Head coverage: 8-30m, meeting pressure requirements for transportation from sewage collection tanks to treatment devices (including filter and elbow resistance losses)

Medium compatibility: Capable of conveying domestic sewage (containing feces, toilet paper), kitchen wastewater (containing bones, vegetable leaves), engine room oily sewage (oil content ≤100ppm), with temperatures ranging from -10℃ to 70℃ and pH 3-11

Self-priming performance: Self-priming height ≥4m, priming time ≤60 seconds (for clean water), capable of direct startup without manual priming

Anti-clogging capability: Flow channel diameter ≥80mm, with flexible diaphragm deformation enabling wrapping of long fibers (≤100mm) for passage. Achieves 99% passage rate for plastic bags and hair, with a clogging rate 95% lower than centrifugal pumps

3.Safety and Anti-Pollution Design

Explosion-proof certification: Motors of stainless steel pumps handling oily sewage adopt Ex d IIB T4 Gb explosion-proof grade, suitable for Zone 2 hazardous areas in engine rooms

Overload protection: Equipped with pressure sensors, automatically shutting down and alarming when pipeline pressure exceeds 1.5 times the rated value due to blockage, avoiding pump body damage

Zero-leakage sealing: Diaphragms and pump covers use embedded sealing structures (compression 0.5mm) with leakage ≤0.1mL/h, preventing sewage leakage and cabin pollution

III. Technical Advantages and Innovative Design

1. Complex Sewage Treatment Capacity

Dual-diaphragm synchronous drive: Adopts symmetric reciprocating design of main and auxiliary dual diaphragms, increasing flow by 50% compared to single-diaphragm pumps with pressure fluctuation ≤±0.05MPa, avoiding pipeline vibration.

Dead-angle-free flow channel design: Flow channels feature smooth S-shaped transitions (curvature radius ≥50mm) without right-angle bends, reducing impurity retention and extending cleaning intervals to 300 hours.

Fiber cutting assistance: Import end integrates rotating blades (300rpm) to cut fiber impurities longer than 100mm (e.g., fishing net threads), further reducing clogging risks.

2. Wear and Corrosion Resistance Enhancement

Diaphragm material upgrade: Perfluoroelastomer (FFKM) diaphragms improve oil and chemical corrosion resistance by 3 times compared to nitrile rubber, with volume change rate ≤5% after 1000 hours of immersion in 100℃ engine oil.

Stainless steel surface treatment: 316L flow components undergo passivation + Teflon coating (0.05mm thickness), doubling salt spray corrosion resistance and suitable for high-humidity ocean-going environments.

Cast iron pump anti-corrosion technology: Inner walls of HT250 pump bodies are sprayed with ceramic composite coating (0.2mm thick) with HRC60 hardness, improving sediment erosion resistance by 80% compared to ordinary cast iron.

3. Ship Operating Condition Adaptability

Lightweight modular design: Single unit weight ≤150kg (20m³/h model), 40% lighter than centrifugal pumps of the same flow, easily installed on engine room tops or in narrow spaces.

Tilt and vibration resistance: Flow attenuation ≤8% under ship heel ±20°, trim ±10°, and vibration acceleration 10g, ensuring stable operation in severe sea conditions.

Intelligent control integration: Optional PLC control system, linked with ship central monitoring to automatic start-stop, fault alarm, and remote monitoring (supporting MODBUS protocol).

IV. Typical Application Scenarios

1. Domestic Sewage Treatment

Passenger ship toilet sewage discharge: 1000-person passenger ships use stainless steel diaphragm sewage pumps (flow 30-40m³/h, pressure 1.2MPa) to convey toilet sewage (containing feces, toilet paper) to biochemical treatment devices, with 1000 hours of continuous operation without clogging.

Cargo ship crew sewage treatment: 200-person cargo ships use cast iron diaphragm pumps (flow 10-15m³/h, pressure 1.0MPa) to pump domestic sewage into small integrated processors, with treated effluent COD ≤125mg/L meeting MARPOL Annex IV standards.

2. Kitchen and Engine Room Sewage

Cruise ship kitchen wastewater treatment: Large cruise ship kitchens use engineering plastic diaphragm pumps (flow 20-25m³/h, pressure 0.8MPa) to convey wastewater containing food residues (particle diameter ≤20mm) to oil separators, achieving ≥98% oil removal rate.

Oil tanker engine room sewage discharge: 30,000 gross ton oil tankers use explosion-proof stainless steel diaphragm pumps (flow 25-30m³/h, pressure 1.6MPa) to convey oily sewage (oil content 50ppm) to oil-water separators, with treated effluent oil content ≤15ppm.

3. Emergency Sewage Discharge Scenarios

Sewage pipe blockage emergency: When main sewage pipes are blocked, portable diaphragm pumps (flow 5-10m³/h) connect to sewage wells via hoses for temporary discharge to backup treatment devices, with of ≥8 hours.

Chemical leakage treatment: After chemical tanker tank washing, perfluoroelastomer diaphragm pumps (flow 15-20m³/h) convey sewage containing trace chemicals (pH=3) to incinerators, with pump bodies showing no corrosion.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Sewage type: Cast iron/stainless steel pumps for domestic sewage; 316L + FFKM diaphragm pumps for oily/chemical sewage; engineering plastic pumps for kitchen wastewater

Flow calculation: Configure according to 150L daily sewage discharge per person (including losses); e.g., a 500-person ship discharging 75m³ sewage daily requires flow ≥12.5m³/h (based on 6 hours of operation)

Pressure requirements: 0.6-1.0MPa for short-distance conveyance (≤10m); 1.0-2.0MPa for long-distance/high-head conveyance

2. Maintenance Points

Daily inspection: Check outlet pressure (fluctuation ≤±0.1MPa) and diaphragm bulging every 200 hours to ensure normal operation

Regular maintenance: Replace diaphragms (nitrile rubber 8000 hours/perfluoroelastomer 15000 hours) and clean check valves every 1000 hours; apply food-grade grease

Deep cleaning: Disassemble pump bodies every 3000 hours and rinse flow channels with 5% NaOH solution to remove oil deposits

3. Compliance Inspection

Annual classification society inspection verifying flow attenuation rate (≤10% with 10% solid content) and explosion-proof performance

Meets MARPOL Annex IV requirements for ship domestic sewage discharge, ensuring compatibility with sewage treatment device

VI. Compliance and Certification

International standards: Complies with ISO 15749 marine diaphragm pump performance standards and IMO MARPOL Annex IV sewage treatment regulations

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

Environmental requirements: When used with marine sewage treatment devices, discharged water has COD ≤125mg/L and suspended solids ≤35mg/L, meeting international anti-pollution requirements