How to Analyze Oil Analysis Reports

Published: 08th June 2007
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The oil analysis report is a vital tool for a smooth running operation. Going deeper than the report summaries and knowing how to analyze the oil analysis report can help prevent equipment breakdown and unnecessary equipment teardowns.

Interpreting an Oil Analysis Report
When all else fails, read the instructions. This is the well established rule of last resort; whether we are putting together a child's toy or trying to operate the latest electronic device. The oil analysis reports are the instructions for smooth running equipments.

Instruction manuals written today are reduced to five quick start steps with big pictures. Oil analysis reports begin with problem summaries and red-letter critical alerts. An oil analysis interpreter immediately glances at the top right hand box for lubricant and machine condition on oil analysis reports. Eyes then graze the summary of the oil sample and the problems found during oil analysis. Then oil analysis report readers grab what they can from the graphs of individual elemental tests.

The oil analysis report, however, has much more to say than a quick diagnosis can offer by scanning for red letters and glancing at colorful graphs. Reading an oil analysis report can be daunting and dull unless you know what you are reading. You must overly analyze the oil analysis report, know your equipment and correctly interpret the results.

Here are some checkpoints to cover when you are reading an oil analysis report.

Read the Name
When you open your reports, make sure they are just that, your reports. Mistakes can be made; be certain the oil analysis report has your name, the company name, the Unit ID, the manufacturer, the model, and the unit type or component. Look for the lubricant manufacture and type, viscosity grade of the oil in the unit, note the time the unit was serviced, and if the oil was changed or makeup oil added.

Now you that you know that the analysis reports belong to you, it is time to know what is circulating around your unit. It is time to read the oil analysis report.

Read the Oil Analysis
You should be able to see a quick summary of the condition of your oil with a cursory glance at your oil analysis report. You should be able to see quickly the problem area in your unit, how bad the problem is, and a suggested course of action from the summary information provided in your oil analysis report.

Take a closer look at your oil analysis report. Understand that the oil analyst is looking at hundreds of samples every day and might become confused or misinterpret some details of your unit and its particulars. Knowing how to read your oil analysis report and knowing your machine will eliminate confusing results. When all else fails, read the oil analysis report carefully.

Analyzing the oil analysis report involves understanding the elements flowing in your oil and at what level. You will read the viscosity level of the oil sample; the water found in the oil; and the acid number (TAN) in your oil analysis report.

Read the Elements
Read the elements circulating in your oil. Some elements are supposed to be there. Other elements found in oil are picked up as the oil circulates and splashes on different components and surfaces of the machine. Some oil trash simply falls into the sump. No matter how the contaminates enter the oil, they are carried along within the oil and cause metal wear.

The key to oil analysis reports is the elemental analysis. There is a wealth of information on your oil analysis report about wear behavior, contaminates entering the system, and the service needed.

You should be asking questions as you read your oil analysis report: What does it all mean? Where is contaminant debris coming from in your unit? What am I looking for that will help me see what is happening inside my unit? Am I looking at suspended particles that are from the additives or from elements being picked up as the oil circulate, or from debris falling into the unit?

These elements are commonly the cause of component wear: iron, chromium, aluminum, copper, lead, tin, nickel, molybdenum, antimony, silver, titanium, and manganese. On your oil analysis report, some elements are single out such as copper or iron and given special attention.

Elements found in your oil sample are measured in parts per million (PPM) - a very small amount. A single PPM is equivalent to 0.0001%. To put that in perspective, it takes 10,000 PPM to equate to 1.0%. Concentrations seen in oil analysis reports will be from one PPM to several hundred PPMS.

Tests performed during an oil analysis to find the elements floating in your oil include an ICP Spectroscopy, Particle Count, FT-IR, and Analytical Ferrography.

The ICP Spectroscopy
This measures the concentration of wear metals, contaminant metals and additive metals. In a repeatable oil analysis test, a diluted oil sample is pulverized by inert gas (argon) to form an aerosol. This is magnetically induced to form plasma at 9000 degrees C. The high temperature causes metal ions to take on energy and release new energy in the form of photons. A spectrum with different wavelengths is created for each element. The instrument quantifies the amount of energy emitted and determines the concentration in parts per million (ppm) of 20 elements present in the sample

The Particle Count
This measures the size and quantity of particles in the oil sample and measured in microns using the Fluid Flow Decay Principle. Fluid Flow Decay Principle means oil is passed through a screen of known mesh size (10 microns) and the time taken to plug the screen is measured.

Wear on the machine, measured in microns, points to the amount of ferrous wear metals present in a sample. Large Ferrous is a measure of particles greater than 5 microns and represents abnormal wear. Small ferrous is a measure of particles less than 5 micron and represents normal rubbing wear.

The FT-IR
This measures the chemical composition of the oil sample and gives an overall degradation of oil. Every element has a unique infrared signature. The key signature of oil is monitored by using a Fourier Transform Infrared (FTIR) Spectrometer. These signatures are usually common contaminants and degradation by-products unique for a particular lubricant.

Analytical Ferrography
This allows an oil analyst examine wear particles present in a sample visually. Oil samples are passed over a glass slide where ferrous wear particles in the oil come to the surface because of the magnetic plate that attracts the ferrous particles. The particles line up forming a ferrogram. A trained oil analyst can visually determine the severity of wear on the unit using a microscope to classify the particles according to size, shape, and metallurgy.

Read the Viscosity
Viscosity is the most important physical property of oil. Viscosity testing measures oil's resistance to flow at a particular temperature. A viscometer is the measuring tool. A "U" Shaped tube holds the oil. The tube is submerged in a steady temperature bath. As the oil warms, it flows down the tube and up the other side. The number of seconds the oil takes to flow through is measured.

Viscosity in centistokes (cSt) is the seconds multiplied by the tube factor. An abnormal viscosity of (+-15%) is a sign there is a problem.
Increases in oil viscosity may be due to the effect of oxidation, contamination, or an addition of a higher viscosity product. Increases in viscosity are a concern, but decreases in viscosity are a greater concern. Decreases in viscosity may occur due to some type of diluting contamination, mechanical shearing of viscosity index or the addition of viscosity products. Decreases in viscosity are critical because they will rapidly produce wear. Lower viscosity levels may be due to water contamination.

Read the Water
Water contamination is a common problem in many systems. This is a rare problem in engines due to high temperatures. In non-engines however, water is a frequent problem.

The Karl Fischer Water Test is used in oil analysis because of its precision. Water contamination is often visible because of the cloud or milky composition caused by oil and water emulsion.
Water problems may come from cooling systems, condensation, environmental issues, or cleaning solutions. Measuring moisture content in some oils with metallic additives causing false reports when there is little or no water present. When in doubt use another test.

Read the Acid
The acid number is useful in monitoring acid build up in oils due to oxidation degradation. An oil analyst must know that the baseline acid value is of the new oil used to determine when the acid number (TAN) has increased to a point where it is time for an oil change. When your oil analysis is red flagged for high acid levels, the oil must be changed or "sweetened" with an addition of a new product. High acid will promote oxidation and eventually corrode metal.

Understanding your oil analysis reports will allow you to get the most out of your Oil Analysis Program. When all else fails, read oil analysis report, the name, the elements, the viscosity, the water, and the acid number to keep your equipment fully functioning. A smooth running operation requires some knowledge of your oil analysis report.

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