Oil analysis is an essential tool in predictive and preventive maintenance of industrial equipment. It allows monitoring the condition of the oil and detecting potential issues in machines before they turn into catastrophic failures. In this article, we will explore in-depth the various oil analysis techniques, their applications and benefits, and how these techniques contribute to improving the efficiency and lifespan of equipment.

 

Oil Analysis Techniques

Oil analysis is an essential tool in predictive and preventive maintenance of industrial equipment. It allows monitoring the condition of the oil and detecting potential issues in machines before they turn into catastrophic failures. In this article, we will explore in-depth the various oil analysis techniques, their applications and benefits, and how these techniques contribute to improving the efficiency and lifespan of equipment.

Importance of Oil Analysis

Oil analysis is crucial for ensuring the proper functioning and longevity of mechanical equipment. The main benefits include:

• Early Detection of Problems: It allows the identification of contaminants and abnormal wear before they cause severe damage.
• Cost Reduction: It helps to avoid costly repairs and unplanned downtime.
• Maintenance Optimization: It facilitates scheduling maintenance based on the actual condition of the equipment, rather than fixed time intervals.
• Prolonged Equipment Lifespan: Keeping oil in good condition extends the lifespan of equipment components.

Oil Analysis Techniques

Several oil analysis techniques are used to evaluate different aspects of the oil and the condition of the equipment. Below are the most common techniques:

Viscosity Analysis

• Description: Viscosity is a measure of the oil's resistance to flow. It is a critical property that affects lubrication performance.
• Technique: Viscosity is measured using a viscometer, which can be capillary, rotational, or falling ball type.
• Applications: Changes in viscosity may indicate contamination, oil degradation, or mixing of different types of oils.

Atomic Absorption Spectroscopy (AAS)

• Description: This technique is used to detect and quantify the presence of wear metals and contaminants in the oil.
• Technique: The oil is atomized and exposed to a light source. The amount of light absorbed at different wavelengths indicates the concentration of specific metals.
• Applications: Identifies metals like iron, copper, aluminum, and lead, which can indicate wear of components like bearings, gears, and pistons.

Particle Analysis

• Description: This analysis detects and quantifies solid particles present in the oil.
• Technique: Optical or electronic microscopes are used to count and classify particles by size and shape.
• Applications: Helps identify sources of contamination and mechanical wear, allowing early detection of problems.

Infrared Spectroscopy (FTIR)

• Description: FTIR is used to identify chemical compounds in the oil.
• Technique: The oil is exposed to infrared light, and the amount of light absorbed at different wavelengths is measured. Each compound has a unique absorption spectrum.
• Applications: Detects the presence of additives, oil degradation products, water, and contaminants.

Total Base Number and Total Acid Number Test (TBN/TAN)

• Description: These tests measure the oil’s ability to neutralize acids and its total acidity, respectively.
• Technique: An oil sample is titrated with a standard solution, and the endpoint is measured using pH indicators or potentiometrically.
• Applications: Indicate oil degradation and the need for oil change, as well as the presence of combustion and oxidation products.

Gas Chromatography (GC)

• Description: GC is used to separate and analyze volatile compounds in the oil.
• Technique: An oil sample is injected into a chromatography column, and the compounds are separated and detected by an appropriate detector.
• Applications: Identifies contaminants such as fuels, coolants, and oil degradation products.

Water Analysis

• Description: The presence of water in the oil can cause corrosion and deterioration of lubrication performance.
• Technique: Methods such as Karl Fischer, distillation, and microwave moisture analysis are used to measure the water content in the oil.
• Applications: Detects leaks in cooling systems and condensation of moisture in equipment operating in humid environments.

Demulsibility Test

• Description: Evaluates the oil’s ability to separate water.
• Technique: An oil sample is mixed with water, and the separation time is observed.
• Applications: Important for hydraulic and circulation systems where water presence is common.

Oxidation Test

• Description: Measures the oil’s resistance to oxidation.
• Technique: The oil is subjected to elevated temperatures, and the increase in oxidation products is measured.
• Applications: Indicates oil stability and expected lifespan.

Implementation of Oil Analysis

Sample Collection

It is crucial to collect representative oil samples to obtain accurate results. Samples should be taken from designated sampling points while the equipment is in operation or shortly after it stops.

Sampling Frequency

The frequency of sampling depends on the criticality of the equipment and operating conditions. Critical equipment may require monthly sampling, while others can be monitored quarterly.

Interpretation of Results

Oil analysis results should be interpreted by trained personnel, considering trends and the manufacturer’s equipment specifications. Abnormal trends should be investigated and addressed immediately.

Corrective Actions

Based on the oil analysis results, various corrective actions can be taken, such as adjusting oil change intervals, additional filtration, repairing worn components, and adjusting operating conditions.

Case Studies

Automotive Industry

An automobile manufacturing plant implemented an oil analysis program in its production equipment. They detected high levels of metallic particles in the oil of an assembly line, indicating abnormal wear. A detailed inspection revealed that a bearing was failing. By replacing the bearing before catastrophic failure, the plant avoided costly downtime.

Power Plant

A power plant used FTIR analysis to monitor the presence of contaminants in the oil of its turbines. They detected a buildup of oxidation products, indicating that the oil was starting to degrade. By changing the oil before it fully degraded, they improved turbine efficiency and extended its lifespan.

Food Processing Industry

A food processing company used base number and acid number tests to monitor the oil condition in its hydraulic systems. They detected an increase in acid number, indicating the presence of combustion products. Upon investigation, they discovered leaks in the system seals, allowing contaminants to enter. They repaired the leaks and changed the oil, improving system performance.

Oil analysis is an invaluable tool for predictive and preventive maintenance of industrial equipment. The various analysis techniques provide detailed information about the oil condition and the state of the equipment components. By implementing a robust oil analysis program, industries can detect problems early, reduce maintenance costs, optimize maintenance scheduling, and prolong the lifespan of their equipment. Investing in oil analysis translates to more efficient, reliable, and profitable operations.