Total Base Number
Encyclopedia
Total base number is a measure of a lubricant
's reserve alkalinity
. It is measured in milligrams of potassium hydroxide
per gram (mg KOH/g).
TBN determines how effective the control of acids formed will be during the combustion process. The higher the TBN, the more effective it is in suspending wear-causing contaminants and reducing the corrosive effects of acids over an extended period of time. The associated measurement ASTM
D2896 and ASTM D4739-06 generally range from 6-80mg KOH/g in modern lubricants, 7-10mg for general automotive use and 10-15 for Diesel operations.
Marine grade lubricants generally will run from 15-50mgKOH/g, but can be as high as 70 or 80mg KOH/g as is the case of Exxon’s MobileGuard 570 or respectively Castrol’s Cyltech 80AW this high level is designed to allow a longer operating period between changes, under harsh operating conditions. When the TBN is measured at 2mg KOH/g or less the lubricant is considered inadequate for engine protection, and is at risk for allowing corrosion to take place. Higher sulfur fuel will decrease the TBN faster due to the increased formation of sulfuric acid
.
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
's reserve alkalinity
Alkalinity
Alkalinity or AT measures the ability of a solution to neutralize acids to the equivalence point of carbonate or bicarbonate. The alkalinity is equal to the stoichiometric sum of the bases in solution...
. It is measured in milligrams of potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
per gram (mg KOH/g).
TBN determines how effective the control of acids formed will be during the combustion process. The higher the TBN, the more effective it is in suspending wear-causing contaminants and reducing the corrosive effects of acids over an extended period of time. The associated measurement ASTM
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
D2896 and ASTM D4739-06 generally range from 6-80mg KOH/g in modern lubricants, 7-10mg for general automotive use and 10-15 for Diesel operations.
Marine grade lubricants generally will run from 15-50mgKOH/g, but can be as high as 70 or 80mg KOH/g as is the case of Exxon’s MobileGuard 570 or respectively Castrol’s Cyltech 80AW this high level is designed to allow a longer operating period between changes, under harsh operating conditions. When the TBN is measured at 2mg KOH/g or less the lubricant is considered inadequate for engine protection, and is at risk for allowing corrosion to take place. Higher sulfur fuel will decrease the TBN faster due to the increased formation of sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
.