Cast Iron Ejector Freshwater Pump

I. Product Overview

Marine cast iron ejector freshwater pumps are core equipment specifically designed for ship freshwater supply systems. Made of gray cast iron (HT250) or ductile iron (QT400-18) as the main material, they achieve efficient freshwater transportation and circulation based on the ejector pump principle (Venturi effect). Their working principle involves using high-pressure water to form a high-speed jet flow through a nozzle, creating a vacuum negative pressure in the suction chamber. This draws in freshwater, which is then transported through a diffuser to various systems on the ship, including the domestic water supply system, main engine freshwater cooling system, and boiler feed water system. After surface treatment with an epoxy resin coating, the cast iron material can operate stably in fresh water with a pH range of 6-8, offering excellent corrosion resistance and mechanical strength. These pumps meet IMO maritime regulations and certification requirements of classification societies such as CCS, ABS, and DNV, and are widely applicable to various ship types, including cargo ships, passenger ships, and engineering vessels.

II. Core Technologies and Material Characteristics

1.Cast Iron Material Selection and Performance

2.Key Technical Parameters

Flow range: 10 - 200m³/h, suitable for ships with a tonnage of 500 - 15,000 tons

Head: 15 - 40m, self-priming height ≥7m, no priming required at startup

Efficiency index: Ejection efficiency ≥65%, 12% - 18% more energy-efficient than traditional centrifugal pumps

Corrosion resistance design: The cast iron surface is coated with epoxy powder (thickness ≥200μm) and passes the 2000-hour salt spray test without rust

III. Technical Advantages and Innovative Design

1. High Efficiency, Stability, and Anti-Clogging Capability

Non-rotating component design: Ejector pumps have no vulnerable parts such as impellers and bearings. They can pass solid particles ≤2mm (such as sediment and rust), reducing the clogging risk by 90%, making them especially suitable for freshwater environments with complex water quality.

Constant pressure water supply technology: Adopting a dual-nozzle linkage design, it automatically adjusts the flow rate and pressure to ensure stable water supply when the ship is tilted up to 15° or in a swaying condition.

2. Low Noise and Long Service Life

Quiet operation: Operating noise ≤68dB, 15dB lower than traditional water pumps, meeting the stringent environmental noise requirements of passenger ships and cruise ships.

Extended maintenance cycle: The close combination of the cast iron body and the coating results in a scaling rate 70% lower than that of ordinary metal pumps, extending the maintenance cycle to 18 months.

3. Cost Advantage and Convenient Maintenance

Economic and efficient: The overall cost is 40% - 60% lower than that of stainless steel pumps, suitable for bulk procurement by ships.

Modular structure: The pump body and pipelines are connected with quick-release joints. During maintenance, there is no need to disassemble the entire unit, reducing maintenance time by 60%.

IV. Typical Application Scenarios

1. Ship Domestic Water Supply Systems

Daily water supply: Gray cast iron ejector pumps provide domestic freshwater for inland passenger ships with a flow rate of 30 - 80m³/h, ensuring stable water supply for areas such as kitchens and bathrooms.

Drinking water purification: Paired with filters and disinfection equipment, they supply drinking water that meets WHO standards for ocean-going ships.

2. Ship Power System Cooling

Main engine freshwater cooling: Ductile iron ejector pumps provide high-pressure freshwater circulation for the main engines of ocean-going cargo ships, with a flow rate of 120 - 180m³/h, ensuring that the cylinder liner temperature is controlled between 85 - 95℃.

Generator heat dissipation: They provide forced cooling for auxiliary ship generators, preventing winding overheating and enhancing equipment operation reliability.

3. Special-purpose Water Supply

Boiler feed water: High-pressure ejector pumps (head ≥35m) provide stable feed water for ship boilers, avoiding the risk of dry burning.

Emergency fire-fighting: Linked with the fire-fighting system, they supply high-pressure freshwater in case of emergencies to meet fire-fighting requirements.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Water quality conditions: Choose HT250 for conventional fresh water, and QT400-18 for fresh water containing trace corrosive substances (such as weakly acidic water)

Pressure requirements: Select HT250 for low-pressure systems (≤1.0MPa), and QT400-18 for high-pressure systems (>1.0MPa)

Flow matching: Configure at 1.3 times the actual water consumption. For example, a passenger ship with 1000 passengers is recommended to have a flow rate of 50 - 70m³/h

2. Maintenance Key Points

Daily monitoring: Check the inlet and outlet pressure and pipeline tightness daily to ensure that the pressure fluctuation is ≤±8%

Regular maintenance: Clean the suction filter (accuracy ≤5mm) quarterly, and remove the scale in the pump cavity with a 3% citric acid solution annually

Anti-corrosion maintenance: Reapply epoxy topcoat every two years, and inspect and repair damaged coating areas in a timely manner

VI. Compliance and Certification

International standards: Comply with IMO Guidelines for Safe Ship Drinking Water Operations and ISO 8680 ship water supply system specifications

Classification society certifications: Passed CCS Rules for the Classification of Steel Ships and ABS Rules for Building and Classing Ships

Hygiene standards: Components in contact with fresh water comply with NSF 61 drinking water safety certification to ensure water quality safety