Reference
Glossary of Marine Lubrication Terms
Short, direct-answer definitions of common marine lubrication terms.
- BN (Base Number)
- A measure of a lubricant's ability to neutralize acidic combustion by-products, expressed in mg KOH/g. Higher BN oils are typically used with higher-sulphur fuels.
- TBN (Total Base Number)
- Another term for Base Number, used interchangeably in marine lubricant specifications.
- TPEO (Trunk Piston Engine Oil)
- A lubricant designed for medium-speed trunk piston diesel engines, used in generators and some propulsion systems.
- EAL (Environmentally Acceptable Lubricant)
- A lubricant formulated to be biodegradable and minimally toxic, used at oil-to-sea interfaces such as stern tubes to meet environmental discharge regulations.
- MARPOL Annex VI
- The International Maritime Organization (IMO) regulation limiting air pollution from ships, including sulphur oxide emissions, which directly affects lubricant selection.
- IMO Tier II/III
- Emission standards set by the IMO for marine diesel engines, influencing which lubricants are compatible with newer, lower-emission engine designs.
- Viscosity Grade (SAE/ISO)
- A classification indicating a lubricant's thickness and flow characteristics at specific temperatures, used to match oil to engine and equipment requirements.
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