Sketch a simple line diagram showing a shipboard oil-water separator in series with a coalescing second stage and describe its arrangement and operation?

flowchart LR
    A[Bilge tank] -->|Oily bilge water| B[Bilge pump]
    B -->|Oily bilge water| C[First stage\nconical plates]
    C -->|Partially treated water| D[Coalescing\nsecond stage]
    D -->|Treated water| E[Oil content\nmonitor 100 ppm]
    E -->|<100 ppm| F[Overboard]
    E -->|>100 ppm| A
    C -->|Oil| G[Oil tank]
    D -->|Oil| G

• Limit: 100 ppm oil content in effluent (MEPC.51(32))
• First stage: Conical plate pack causes oil globules to coalesce; oil collects in dome; test cocks show oil depth; automated oil-drain valve opens at set level
• Second stage: Coalescing media merges small droplets into larger ones for final separation
• Monitor: Oil-content monitor on overboard line alarms and diverts to bilge tank if >100 ppm
• Pre-use: Must be filled with clean water before first operation; never exceed rated throughput
• Trap: Turbulence from over-throughput re-entrains oil; unit must not run dry
• Record: Discharge logged in Oil Record Book Part I