Naniwa FH 50/43

Common issues

• Loss of prime or failure to reach rated pressure from a worn impeller, suction air leaks, or a clogged sea strainer
• Mechanical seal or gland packing leakage
• Bearing wear causing vibration or noise
• Relief/pressure-control valve malfunction causing incorrect pressure at hydrants
• Corrosion of casing or impeller during long standby periods with stagnant seawater
• Coupling misalignment
• Failure of remote/local start on the emergency fire pump, or fuel supply issues if engine-driven

Inspection checklist

• Weekly running test - confirm the pump starts and reaches operating pressure within the required time
• Check pressure at the remotest hydrant against the vessel's approved fire control plan minimum
• Inspect suction strainer/sea chest for blockage
• Check mechanical seal or packing gland for leaks
• Verify isolation valves operate freely and are in the correct position
• Check pressure gauge and relief valve function
• Inspect coupling alignment and guard
• Test remote start of the emergency fire pump from outside the machinery space
• Check for external corrosion or leaks at casing joints and flanges

Service intervals

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Mechanical seal or packing set
• Impeller
• Bearings
• Coupling element
• Suction strainer element
• Relief valve repair kit
• Gasket and O-ring set

Safety

• Discharge is at high pressure - secure hoses/nozzles before opening the valve
• Rotating coupling requires guarding
• The emergency fire pump often has an independent power source - follow its own electrical isolation procedure
• Confirm the seawater suction valve is open before testing to avoid dry-running damage
• Hot surfaces present if the emergency unit is diesel-driven

Class survey

Main and emergency fire pumps are SOLAS-mandated items surveyed for rated capacity (two jets from separate hydrants reaching the specified height/throw) and the independent location/power supply required for the emergency unit. Surveyors typically want records of the weekly and annual capacity tests; failure to demonstrate rated pressure at the most remote hydrant is a common deficiency.