Cast Iron Ejector Bilge Pump

I. Product Overview

Cast iron ejector bilge pumps are high-efficiency drainage devices designed for marine bilge water discharge systems. Made of gray cast iron (HT250) or ductile iron (QT400-18), they enable rapid pumping of bilge water (mixed media containing oil, sediment, rust, etc.) based on the ejector pump principle (Venturi effect). The core principle is that high-pressure water flows through a nozzle to form a high-speed jet, creating vacuum negative pressure in the suction chamber to draw in bilge water and discharge it through a diffuser. After surface anti-corrosion treatment (such as zinc-based plating or epoxy coating), the cast iron material can operate stably in seawater with Cl⁻≤20,000ppm and bilge water with pH 5-9, suitable for bilge water discharge in cargo ships, passenger ships, special vessels, etc., meeting IMO MARPOL Annex I anti-pollution conventions and classification society (CCS/ABS/DNV) certification requirements.

II. Core Technologies and Material Characteristics

1.Cast Iron Material Selection and Performance

2.Key Technical Parameters

Flow range: 10-150m³/h, suitable for ships of 500-10,000 tons

Head: 15-30m, self-priming height ≥7m (no priming required)

Efficiency index: Ejection efficiency ≥65%, 8%-12% higher than traditional centrifugal pumps

Corrosion resistance design: Cast iron surface with Ni-P alloy plating (thickness 25-35μm), passing 1,500-hour salt spray test (GB/T 10125) without pitting

III. Technical Advantages and Innovative Design

1. Anti-Clogging and Complex Media Adaptability

Non-Rotating Component Design: Ejector pumps have no rotating parts such as impellers or gears, capable of passing ≤5mm solid particles (e.g., rust, rags), reducing clogging risk by 90% compared to centrifugal pumps.

Oil-Water Separation Capability: In oily bilge water (oil content ≤300ppm), the velocity gradient design of the diffuser enables oil-water stratified discharge, improving the efficiency of oil-water separators by 30%.

2. High Reliability and Marine Condition Adaptation

Anti-Tilt Performance: Stable drainage under ship trim 15° and list 10°, adapting to ship swaying environments.

Explosion-Proof Safety Design: Cast iron material generates no sparks during friction. Combined with explosion-proof motors (Ex d IIB T4), it is suitable for hazardous bilges containing combustible gases (such as cargo bilges of oil tankers).

3. Convenient Maintenance and Cost Advantage

No-Disassembly Cleaning: Smooth flow channel of ejector pumps (roughness Ra≤12.5μm), scaling rate 70% lower than centrifugal pumps, reducing annual cleaning frequency by 50%.

Cast Iron Cost Advantage: Overall cost is 40%-60% lower than stainless steel ejector pumps, suitable for mass installation on ships.

IV. Typical Application Scenarios

1. Bilge Drainage for Merchant Ships

Cargo Ship Engine Room Bilge: HT250 ejector pumps drain engine room water containing lubricating oil, flow 50-100m³/h, combined with oil-water separators to achieve compliant discharge (oil content ≤15ppm).

Passenger Ship Sanitary Bilge: QT400-18 ejector pumps handle bilge water containing domestic sewage, self-priming height 8m, adapting to multi-deck bilge drainage needs.

2. Emergency Drainage for Special Vessels

Offshore Engineering Vessels: Dual ejector pump parallel design (flow ≥150m³/h) enables rapid drainage under drilling platform tilt conditions, meeting SOLAS convention emergency drainage requirements.

Fireboat Bilge: High-temperature resistance design (temperature ≤80℃), capable of draining high-temperature bilge water after fire fighting, 联动 with fire protection systems.

3. Oil Tankers and Hazardous Cargo Vessels

Oil Tanker Cargo Bilge: QT400-18 ejector pumps with anti-static design (grounding resistance ≤4Ω) drain bilge water containing crude oil residues, avoiding spark risks.

Chemical Tanker Bilge: Cast iron surface with Teflon coating (thickness 50μm) resists minor chemical corrosion (such as methanol, styrene).

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Water Quality Conditions: Choose HT250 for oil content ≤15ppm, QT400-18 for particulate/high-salt water

Ship Tilt Requirements: Ocean-going ships should select QT400-18 (superior anti-tilt performance)

Flow Matching: Configure at 1.5 times the maximum bilge water generation, e.g., 5,000-ton cargo ships recommend flow 80-120m³/h

2. Maintenance Points

Daily Monitoring: Check nozzle wear (allowable diameter wear ≤0.5mm) and vacuum pressure (≥0.04MPa) daily

Regular Maintenance: Clean the suction grille (filtration accuracy ≤10mm) quarterly, remove pump cavity scale with 5% dilute hydrochloric acid (soaking ≤15 minutes) annually

Anti-Corrosion Maintenance: Reapply epoxy glass flake paint every two years (dry film thickness ≥200μm)

VI. Compliance and Certification

International Standards: Complies with IMO MARPOL Annex I Regulation 15 for bilge water discharge

Classification Society Certification: Passed CCS Rules for the Classification of Steel Ships and ABS Rules for Building and Classing Ships

Environmental Requirements: Oil content in ejected water ≤15ppm, solid particles ≤50mg/L