15 ppm Bilge Alarm and Oil Content Meter Calibration Guide
Plan calibration and functional testing of 15 ppm bilge alarms and oil content meters, with practical checks for sampling lines, records, seals and automatic stopping devices.
The 15 ppm bilge alarm monitors treated bilge-water discharge from oily-water separating equipment. Under MARPOL Annex I and the approval framework in MEPC.107(49), the monitoring and automatic stopping arrangements help prevent discharge above the permitted oil-content limit. Calibration alone cannot compensate for blocked sample lines, incorrect valves or poor oily-water separator operation.
Identify the complete system
Provide monitor maker, model, serial number, approval certificate, software version where relevant, measuring-cell type, last calibration and separator details. Confirm the arrangement of sampling, flushing, overboard diversion and automatic stopping devices against approved drawings.
What attendance should cover
The scope may include visual examination, zero and span verification with accepted standards, alarm-point testing, response-time checks, recorder and data verification, automatic stopping-device demonstration, seal inspection and review of sample flow. Maker procedures and flag/class instructions define whether adjustment, calibration or maker-authorised service is required.
Prepare before the technician arrives
- Clean the measuring cell according to maker instructions.
- Check sample and fresh-water lines for blockage, leakage and incorrect connections.
- Make the separator available for safe functional testing.
- Provide calibration certificates, manuals and previous reports.
- Confirm access to valves, stopping devices and data records.
- Arrange class or flag witnessing if required.
Common deficiencies
Inspectors may find expired calibration evidence, broken seals, unreadable displays, non-functioning alarms, incorrect date and time, missing historical data, bypassed stopping devices, contaminated optical cells, inadequate sample flow or undocumented replacement sensors. Unexplained piping modifications can raise serious concerns about bypass arrangements.
Calibration standards and traceability
Use standards, tools and procedures accepted for the instrument. The report should identify reference materials, serial numbers, results before and after adjustment, alarm response and technician authority. A sticker without measured results or traceability provides limited assurance.
Operational records
Oil Record Book entries, alarm-recorder data, separator operation and maintenance records should tell a consistent story. Preserve required monitor records and investigate repeated high alarms. Crew should understand flushing, startup, shutdown and actions following an alarm.
After repair or component replacement
Replacement of a measuring cell, controller or software may affect approval and calibration. Confirm component compatibility and repeat the required functional tests. Restore seals and update drawings or spare-part records where arrangements changed.
Arrange calibration
Review oil content meter and bilge alarm calibration and submit instrument details, certificates, fault history and port schedule through the quotation form.
References
Consult MARPOL Annex I, IMO Resolution MEPC.107(49), the approved installation drawings, flag/class instructions and the equipment manufacturer’s current service manual.
Technical guidance notice. Last reviewed September 3, 2026. Requirements can vary by flag, class, vessel, equipment maker and Administration. Confirm the current authoritative requirements before arranging inspection, testing or repair.