TBN Analysis in Lubricants: Oil Acidicity and Performance Evaluation

What is the Total Base Number (TBN) in Lubricants?

What is TBN (Total Base Number)?

Total Base Number (TBN) is a measure that determines the acid neutralizing capacity of a lubricant. TBN refers to the concentration of base (alkaline) substances in the oil and is usually measured in mg KOH/g (milligran potassium hydroxide/g). The TBN test determines how effectively the oil contains neutralizing bases against acidic substances that have accumulated in the oil.

Oils oxidize over time when working in engines or machinery, leading to the formation of acidic compounds. These acidic compounds can damage metal surfaces, causing wear and corrosion. TBN analysis measures how much alkaline the oil contains to protect against these acidic compounds.

TBN Test: How Is It Performed?

TBN analysis is usually performed by the titrimetric method. In this test, a certain amount of fat is sampled and titrated to neutralize the acidic components. The process consists of the following steps:

Sample Preparation: The lubricant sample is made suitable for titration. Usually, the sample is soluble in a specific solvent.
Addition of Titrant: A specific alkaline solution (e.g. potassium hydroxide - KOH) is added to the oil sample to neutralize the acidic compounds.
Titration: By adding the titrant, the acidic components in the oil are neutralized. During the titration, the pH change is monitored.
Calculation of Results: The amount of titrant added until the end of the titration is measured and recorded as the TBN value of the oil.

What Does TBN Value Mean?

The TBN value reflects the neutralizing capacity of the oil against acidic compounds. A high TBN indicates that the oil has a high capacity to fight acidic compounds and that this oil can last longer. Below is a general guide to what TBN values mean:

High TBN (≥ 10 mg KOH/g): The oil has an abundance of bases, indicating a high capacity to neutralize acidic compounds. This type of oil can cope with oxidation and acidic contamination and is often used in heavy duty engines or high temperature conditions.
Medium TBN (6-9 mg KOH/g): Oils with a medium base content are adequate when operating under normal conditions. These oils are suitable for daily use and generally for light-duty engines.
Low TBN (≤ 5 mg KOH/g): The oil contains a low amount of base and such oils can neutralize fewer acidic compounds. These oils are generally suitable for shorter-term use and may need to be replenished quickly.

Importance and Uses of TBN Analysis

TBN analysis plays a critical role in the maintenance and performance evaluation of lubricants. The TBN value is an important quality indicator, especially for motor oils and industrial lubricants. Here are the most common areas where TBN testing is used:

Automotive Industry: Engine oils must have sufficient neutralization capacity against acidic compounds for long life. For this reason, the TBN value of oils used in automotive engines is regularly tested.
Industrial Applications: Since heavy industrial machinery operates under high temperatures and oxidation conditions, the TBN value of the oils used in these machines increases the life and efficiency of the machines.
Marine: Marine engines are more sensitive to extreme oxidation and acidic fouling. Therefore, the TBN level of oils used in the marine industry is monitored.
Oil and Gas Industry: TBN levels of oils used under high temperature and intensive operating conditions are monitored for the effectiveness of their protective properties.

Benefits of TBN Analysis

Oil Life Monitoring: TBN analysis determines how long the oil can be used effectively. If the TBN level of the oil drops, this is an indication that the oil needs to be changed.
Improving Engine Performance: Monitoring the capacity of oils to neutralize acidic components ensures efficient operation of engines and machinery. A low TBN level can increase the risk of wear and corrosion in engines.
Early Intervention: A drop in TBN levels is an indication that the oil is beginning to oxidize. This allows early intervention to change the oil and protect the engine.
Cost and Time Savings: Regular monitoring of oils allows optimizing the frequency of oil changes and thus reducing maintenance costs.

Nanolab Laboratories Group continues to provide services within the scope of TBN Analysis in Lubricants. We also provide services on Total Oil Number (TAN) Analysis in Lubricants.

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