Oil Analysis - Contaminents
In addition to wear metals, ferrous debris, and combustion products in lubrication oils, other contaminants can include:
A major cause of engine or machine failure is dirt contamination. It acts as an abrasive on most metallic surfaces and can cause severe problems. The presence of excessive dirt contamination can be picked up by a visual appearance of a sample but can also be seen in the spectrometric (ICP-OES) analysis of the samples.
The type of dirt found depends on the material being handled and the working conditions of the equipment, but generally dirt is silicon based. Off-highway plant machinery and road vehicles are generally in contact with silicate dirt or grit from roads and concrete. Special processes, however, may also include titanium oxides, limestone or coal etc as the major dirt component, whilst marine vessels will of course include cargo debris, sand and salt.
It is essential to be aware of these factors during the diagnosis of results. We therefore base our interpretations on the analysis of over 20 elements, which cover most, if not all of these possibilities.
A ratio of 3:1 of Silicon to Aluminium on a sample report is indicative of environmental dirt.
Fuel Dilution is measured by various methods namely, viscosity, FTIR (Fourier Transform Infra-Red Spectrometry), flash point, fuel sniffer and Gas Chromatography. These tests are essential to detect over rich mixtures, faulty injector systems and leaking pipework. An excess of fuel dilution can lead to poor lubrication and excessive wear or failure.
Abnormal - More than 2% fuel
Serious - More than 4.5% fuel
Glycol is one of the worst enemies of lubricating oils. Found in most antifreeze solutions, glycol can enter oil supplies in many of the same ways water does. When mixed with oil at operating temperatures, the glycol/oil mixture changes chemically to form highly corrosive sludge deposits.
Rapid deposit formation causes a marked increase in oil viscosity (thickness) impairing the oil´s flow characteristics, totally plugging up component systems, causing lubricant starvation. The resulting excessive wear problems are sometimes catastrophic.
If present for any length of time, these deposits will readily bond themselves to moving parts, totally displacing the oil and in extreme cases, causing components to seize.
If a coolant leak is the source of the water contamination, then glycol may be present.
To check for glycol we can analyse the samples with FTIR (Fourier Transform Infra-Red Spectrometry) or Gas Chromatography.
Water can be found as a contaminant in any lubricated system and can rapidly reduce the lubricants’ quality as well as increasing the levels of wear debris in the equipment.
Water can be introduced into a system via poor sampling or storage procedures, or can be derived from the atmosphere, sea or rainwater and can be introduced by leaking seals, and air breathers with no desiccators. Water is also a problem with machinery which has cooling system problems.
Water can readily be detected by the simple crackle test. Indeed, qualitatively, the crackle test is an extremely reliable test. Simply by dropping an oil onto a hot plate at over 100oC will cause the water if present, to crackle (just like dropping your chips into a chip pan!)
No crackling noise confirms the there is less than 500ppm of water present. However it does not mean that there is no coolant leak: the water may have evaporated off from the hot oil.
If water is present, it is then quantified by various laboratory methods to determine the concentration. In some larger turbine systems it is necessary to measure the water down to single figures of parts per million. Such samples are analysed using a Karl Fischer instrument.
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