Ships are provided with an independent diesel or electric or air operated emergency fire pump.

• In a separate compartment outside the main machinery space (e.g. in a dedicated emergency fire pump room, often forward or in a separate space), so that a fire in the engine room does not disable the pump. Reason: the emergency fire pump must be independent of the main machinery space so it can supply the fire main even if the engine room is on fire.
• In a space above the waterline (e.g. on a deck or in a compartment above the bulkhead deck), so that the pump can take suction and is not flooded. Reason: the pump must be able to operate even if the lower spaces are flooded.
• In a space protected from fire and weather, with its own power source (a diesel engine, or an electric motor supplied from the emergency generator, or an air-operated pump). Reason: the pump must have an independent power source so it can operate when the main power is lost.

Sketch: A priming arrangement for a centrifugal fire pump situated above the waterline consists of a priming pump (a small air pump or a vacuum/eductor) connected to the pump casing. The priming pump draws the air out of the pump and the suction line, creating a vacuum, so that the water is drawn up into the pump (the atmospheric pressure forces the water up the suction line). Once the pump is primed (full of water), the main pump can discharge. The priming pump may be a small reciprocating air pump, a rotary vacuum pump, or an eductor (venturi) operated by a water supply.

Suction lift: A single-stage centrifugal pump can normally achieve a suction lift of about 3-4 metres (the practical limit for a self-priming centrifugal pump is about 3-4 m, though the theoretical maximum is about 10 m at sea level; in practice 3-4 m is the reliable figure for a single-stage pump). The pump must be located so that the suction lift is within this limit.

The emergency fire pump must be capable of delivering at least two jets of water (two fire hoses) simultaneously, each of the required pressure and flow, to the required parts of the ship. Per SOLAS, the emergency fire pump must be capable of delivering a total of at least 25 m3/h (for cargo ships) at the required pressure (e.g. a nozzle pressure of at least 0.25 MPa/2.5 bar at the hydrants), and must be able to supply the fire main. The exact capacity depends on the ship's size and the number of jets required.

• Regular testing: the emergency fire pump is tested periodically (e.g. weekly/monthly) by starting it and running it, and by operating it on the fire main to confirm it delivers the required pressure and flow.
• Maintenance: the pump, its engine/motor, the priming system, the valves and the suction/discharge lines are maintained per the planned maintenance system; the fuel (for a diesel pump) is kept topped up, the battery/starting system is maintained, and the pump is kept clean and free of corrosion.
• The pump is operated during the fire drills and the tests are recorded.
• The pump is inspected at the surveys (e.g. the Safety Equipment survey) and any defects are rectified.

In sub-zero temperatures, the emergency fire pump and its suction/discharge lines and the fire main can freeze, which would disable the pump. Precautions include:

• Keeping the pump room/compartment heated (or the pump and lines protected from freezing).
• Draining the pump and the lines after use, or keeping them warm, to prevent freezing.
• Using a suitable antifreeze or keeping the water circulating.
• Ensuring the pump can be started and the suction is not frozen.
• The fire main and the hydrants are protected from freezing (drained or heated) so they are available in an emergency.

Sketch: The emergency fire pump takes suction from the sea (a sea chest/suction) and discharges through a discharge line to the fire main. The discharge line is connected to the fire main through an isolation valve (a non-return valve and an isolating valve), so that the pump can supply the fire main. The international shore connection is fitted to the fire main (usually on the main deck, at a suitable location) so that the ship's fire main can be connected to the shore firefighting water supply (or the ship can supply the shore). The international shore connection is a standard flange/connection that allows the shore fire hoses to be connected to the ship's fire main.

Reasons: The isolation valve allows the emergency fire pump to be isolated from the rest of the fire main (e.g. for maintenance, or to prevent backflow), and the non-return valve prevents water from flowing back into the pump. The international shore connection allows the ship to receive water from the shore (or supply the shore) in an emergency, providing an additional water supply for firefighting. The connection is located so that it is accessible and can be used by the shore fire service.