Emergency Bilge Suction on Ships: SOLAS Requirements and How It Works

The suction is also fitted with a non-return valve.

If the Administration considers the main circulating pump unsuitable, SOLAS permits the emergency suction to be connected to the largest available independent power-driven pump meeting the applicable requirements.

The arrangement therefore varies according to the vessel's approved design.

Why Is a Non-Return Valve Important?

The non-return valve prevents flow in the wrong direction through the emergency suction arrangement.

This is particularly important where a seawater circulating pump is involved because an incorrect flow path could allow seawater to enter the machinery space rather than remove it. Correct valve operation is therefore essential.

Valve Accessibility

During serious flooding, equipment at the lower level of the engine room may quickly become inaccessible.

SOLAS II-1/35-1 therefore requires the spindles of the sea-inlet and direct-suction valves to extend well above the engine-room platform.

This allows the valves to remain accessible as water accumulates below.

How Does Emergency Bilge Suction Work?

A simplified arrangement can be represented as:

Machinery-space bilge → emergency suction valve → main circulating/suitable pump → overboard

When emergency suction is required, the appropriate valves are positioned so the pump draws water directly from the machinery-space drainage level instead of through its normal suction arrangement.

The exact procedure varies between ships.

Seafarers must therefore follow the vessel's approved piping arrangement and operating procedure. Incorrect valve operation can have serious consequences.

What Should Seafarers Know?

Engineering personnel should be familiar with:

• the location of the emergency bilge suction;
• which pump is used;
• the emergency suction valve;
• associated sea-suction valves;
• the non-return arrangement;
• valve operating positions; and
• the ship-specific emergency procedure.

The most important point is knowing the correct valve line-up before flooding occurs.

Emergency Bilge Suction Is Not an Emergency Bilge Pump

This distinction is important.

SOLAS does not simply require a dedicated piece of machinery called an “emergency bilge pump.”

The emergency arrangement uses a suitable pump through a dedicated direct suction arrangement.

Therefore:

Emergency bilge suction = suction arrangement

Pump = main circulating pump or another suitable independent power-driven pump, as applicable

Final Thoughts

Emergency bilge suction provides an important additional means of removing large quantities of water during serious machinery-space flooding.

Under SOLAS II-1/35-1, the arrangement can use the main circulating pump or, where that pump is unsuitable, another suitable independent power-driven pump.

For seafarers, three questions matter most:

Which pump is used? Where is the emergency suction valve? Do you know the correct valve line-up?

Knowing these answers before flooding occurs can save critical time during an emergency.

Reference

International Maritime Organization (IMO). SOLAS Consolidated Edition 2024, Chapter II-1, Regulation 35-1 - Bilge pumping arrangements.