Marine Diaphragm Freshwater Pump

I. Product Overview

Marine diaphragm freshwater pumps are the "sanitary-grade conveying experts" of ship freshwater supply systems, designed specifically for conveying clean freshwater for crew domestic use, medical purposes, and equipment cleaning. Through the reciprocating deformation of food-grade rubber diaphragms to create volume changes, they achieve negative pressure suction and low-pressure conveyance, fundamentally solving the problem of water contamination caused by metal contact in traditional impeller pumps. Constructed with stainless steel (304/316L), engineering plastic (PP + glass fiber), or cast iron (HT200 + food-grade coating) as the main material, and diaphragms made of food-grade nitrile rubber (NBR) or silicone rubber (VMQ), they are compatible with media such as drinking freshwater containing trace minerals and softened water (turbidity ≤1NTU). The pump body undergoes sanitary-grade treatment and precision sealing, with a service life of ≥8 years in -5℃~60℃ environments. It meets IMO Ship Accommodation Specifications (SOLAS Chapter II-1) and freshwater system certification requirements of classification societies such as RS, LR, ABS, and CCS, widely used in freshwater supply systems of passenger ships, research vessels, and luxury cruise ships with strict water quality requirements.

II. Core Technologies and Material Characteristics

1.Material Selection and Performance

2.Key Technical Parameters

Flow range: 3-30m³/h, suitable for ships with 50-500 personnel (e.g., 200-person passenger ships require flow ≥8m³/h)

Head coverage: 8-25m, meeting water supply pressure requirements from freshwater tanks to high-rise cabins (including pipeline elbows and filter resistance losses)

Medium compatibility: Capable of conveying drinking freshwater (meeting GB 5749 standards), softened water (hardness ≤0.03mmol/L), and medical ultra-pure water, with temperatures ranging from -5℃ to 60℃ and pH 6-8

Self-priming performance: Self-priming height ≥3m, priming time ≤30 seconds (for 20℃ clean water), capable of directly drawing water from low-level freshwater tanks without manual filling

Sanitary indicators: Flow component inner wall roughness Ra≤0.8μm, bacterial retention rate ≤0.1%, effluent colony count ≤10CFU/mL, meeting food contact standards

3.Safety and Sanitary Design

Food-grade certification: Flow components comply with GB 4806.9 (stainless steel) and GB 4806.7 (plastic) standards; diaphragms have passed FDA and LFGB food contact certifications

Anti-recontamination: A sanitary check valve installed at the outlet prevents residual water in pipelines from flowing back to freshwater tanks after shutdown, ensuring water quality remains uncontaminated

Silent operation: Flexible contact between diaphragms and pump chambers results in operating noise ≤55dB (at 1 meter), meeting noise requirements for crew living areas and medical cabins

III. Technical Advantages and Innovative Design

1. Sanitary Conveying Guarantee

Fully enclosed flow channel structure: Diaphragms and pump chambers form a completely enclosed conveying space, preventing freshwater from contacting any driving components and avoiding contamination from mechanical seal leakage in traditional pumps.

CIP online cleaning function: Integrates cleaning interfaces, enabling online flushing of flow channels with high-temperature hot water (80℃) or chemical cleaners (e.g., 0.5% nitric acid solution) for disinfection without disassembly, improving cleaning efficiency by 60%.

Dead-angle-free design: Flow channel corners use R≥5mm arc transitions, with no grooves on diaphragm and pump cover sealing surfaces, completely eliminating sanitary dead angles and meeting GMP cleanliness standards.

2. Operational Stability Enhancement

Dual-diaphragm balance design: Adopts left-right symmetric dual-diaphragm structure, with axial forces canceling each other during operation. Vibration amplitude ≤0.1mm, reducing noise by 15dB compared to single-diaphragm pumps.

Flexible drive system: Uses eccentric wheels + connecting rods to drive diaphragms, avoiding rigid impact. Diaphragm service life reaches 10,000 hours (approximately 1.5 years), doubling that of traditional plunger pumps.

Pressure compensation function: Equipped with pressure sensors and variable frequency motors, automatically increasing rotational speed (flow increases by 20%) when multiple water points are used simultaneously to ensure outlet pressure fluctuation ≤±0.02MPa.

3. Ship Operating Condition Adaptability

Lightweight and compact design: Single unit weight ≤80kg (10m³/h model), 30% smaller in volume than centrifugal pumps of the same flow, suitable for installation on engine room tops or in living cabin mezzanines.

Tilt resistance: Flow attenuation ≤3% under ship heel ±15° and trim ±10°, ensuring stable water supply in severe sea conditions.

Low-temperature anti-freezing design: In -5℃ environments, pump body interlayers can be filled with hot water (from ship heating systems) to prevent freshwater from freezing inside the pump, ensuring normal startup in winter.

IV. Typical Application Scenarios

1. Domestic Drinking Water Supply

Passenger ship centralized water supply: 500-person luxury cruise ships use 304 stainless steel diaphragm freshwater pumps (flow 15-20m³/h, pressure 0.8MPa) to pressurize and convey clean water from freshwater tanks to guest room faucets. Outlet pressure stabilizes at 0.3-0.5MPa, meeting washing and drinking needs, with water quality complying with EU EC 10/2011 standards.

Fishing boat crew water use: 100-person ocean-going fishing boats use 316L stainless steel diaphragm pumps (flow 5-8m³/h, pressure 0.6MPa) to convey desalinated water (salt content ≤500ppm) from seawater desalination equipment to kitchens and showers. Diaphragm chlorine ion corrosion resistance ensures 3 years of leak-free operation.

2. Medical and Special Water Use

Medical ship ultra-pure water conveyance: 50-bed medical ships use engineering plastic diaphragm pumps (flow 3-5m³/h, pressure 0.5MPa) to convey ultra-pure water (resistivity ≥18.2MΩ・cm) to operating rooms and laboratories. Metal-free flow channels meet medical water purity requirements.

Laboratory precision water supply: Research vessel laboratories use 316L diaphragm pumps (flow 2-3m³/h, pressure 0.4MPa) to provide stable water flow for water quality analysis instruments, with pressure fluctuation ≤±0.01MPa ensuring accurate detection data.

3. Emergency and Special Scenarios

Freshwater system failure emergency: When main freshwater systems fail suddenly, portable 304 stainless steel diaphragm pumps (flow 3-5m³/h) connect to backup freshwater barrels via food-grade hoses to supply emergency water to medical rooms and bridges, with of ≥12 hours.

Polar low-temperature water supply: -5℃ polar expedition ships use 316L diaphragm pumps with insulation layers (flow 8-10m³/h) to convey warm water (10℃) from freshwater tanks to living areas. Pump bodies remain free of ice blockages, with outlet water temperature ≥8℃.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Water quality requirements: 304 stainless steel pumps for ordinary drinking freshwater; 316L stainless steel pumps for desalinated water and high-salt freshwater; engineering plastic pumps for ultra-pure water and medical water

Flow calculation: Configure according to 200L daily water consumption per person (including losses); e.g., a 300-person ship requiring 60m³ water daily needs flow ≥10m³/h (based on 6 hours of operation)

Pressure requirements: 0.3-0.6MPa for low-rise cabins; 0.6-1.0MPa for high-rise cabins (≥5 floors)

2. Maintenance Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.03MPa) and leaks weekly; sample and test water quality (colony count, heavy metal content) quarterly

Regular maintenance: Replace diaphragms (food-grade NBR service life 8000 hours/silicone rubber 12000 hours) every 1000 hours; clean inlet filters and apply food-grade grease to transmission parts

Disinfection maintenance: Rinse pump bodies with 80℃ hot water for 30 minutes monthly; disinfect with 0.1% peracetic acid solution every six months to ensure sanitary indicators meet standards

3. Compliance Inspection

Annual classification society inspection focusing on verifying water quality safety (heavy metal content ≤0.001mg/L), flow stability, and sanitary compatibility

Meets SOLAS Convention requirements for ship domestic water systems, ensuring emergency diaphragm pumps can restore water supply to key areas within 30 minutes after main system failure

VI. Compliance and Certification

International standards: Complies with ISO 8316 marine manual pump performance standards and IMO Ship Drinking Water System Hygiene Specifications (MEPC.159(55))

Classification society certifications: Obtained type approval for diaphragm freshwater pumps from RS, LR, ABS, and CCS (including 500-hour sanitary performance tests)

Material compliance: Flow components meet FDA 21 CFR 177 (US food-grade standards) and EU 10/2011 (EU food contact material standards)