Oil analysis should be the primary Condition Monitoring Tool for Diesel Locomotives. The major benefits are in detecting fuel leaks and coolant leaks.
A number of other benefits associated with Equipment Life and Reliability are available from an effective Oil Analysis program.
Many rail operators and the OEMs, specify drops in viscosity to determine if a fuel leak is present. The risk of fuel leaks are if the concentration in the sump of fuel gets too high the engine can explode.
Viscosity as a measure of fuel dilution is a problem as the age of the oil affects the readings. Standard tables of fuel dilution vs viscosity are established for virgin or new oil. The ratios are different for used oil. The fleet operator / maintainer really needs to understand the levels of changes in viscosity that actions are generated at. Techenomics has experience in this area and can help you understand this problem.
Oil analysis will tell you the severity of a coolant leak where coolant is leaking into the internals of the engine. Both rate of change and absolute values should be considered to determine severity. Actions need to be equipment / class specific as different engines respond differently to water leaks and repair methods.
Compressor life is directly related to oil cleanliness. Compressor oil should be measured to ISO Cleanliness grades. These readings can them be used as a basis of an oil cleanliness program designed to extend compressor life.
Base on the results of Oil Analysis specific inspections can be identified to improve the inspection process. Eg if Iron high then do inspection 1 if both Iron and Copper high then slightly different inspection is required.
The only hydraulic machine on some older locomotives is the Hydraulic governor. It is critical oil is very clean in the governor as debris can block valve ports and spindles and cause the governor to not operate correctly. Oil cleanliness can be measured for the governor oil but the root cause is often incorrect top up of governor oil. Techenomics has experience of working with customers to set in place an oil cleanliness program for governor oil.
Spectrographic Element Analysis
Understanding the wear metals in an engine is used to highlight internal problems. Specific actions / inspections can be generated based on the wear metals identified which are above alarm. One Techenomics customer is working towards not even doing the full engine inspection unless warranted by oil analysis.
- Engine life extension. Some operators are choosing to not overhaul engines at the intervals defined by the OEM. Instead they have an inspection based program with oil analysis as a core ingredient to determine which locomotives warrant overhaul.
- Acceptance testing of new and overhauled locomotives. When a new locomotive goes into service samples of the new oil added and after run in should be taken and sent to the operator to give base line readings for the engine and ensure the engine is in good condition.
Oil Life Measuring.
Modern 2 stroke engines (Tier 3) do burn oil like earlier locomotives. They require sweetening / oil changes that previous classes of engines did not. TBN (Total Base Number) is the best measure for determining oil life. TBN is also the best measure for 4 stroke engines oil life.
The TBN alarm levels are dependent upon the oil additive pack used. Currently some operators are experiencing problems of Fire Face and Turbo Charger build-up, one of the most likely causes is the additive pack for the oil is not aligned with the Sulphur content of the fuel. With the advent of Ultra Low Sulphur Fuels in some markets the additive pack needs to be adjusted to lower TBN levels. Techenomics has worked with one customer already to help resolve these issues.
Virgin Oil Sampling
Best practice is to regularly sample your bulk oil facilities to ensure the oil you are putting into your locomotives is up to spec. Recently Techenomics worked with a customer to help resolve issues where one bulk oil tank had been contaminated with water and separately a supplier of oil sent some tetra packs that had oil that had slightly lower viscosity readings then those recommended. Once an Oil Analysis program is in place Virgin Oil sampling is one of the steps on the journey to best practice.
Techenomics has developed a lot of knowledge specific to the Rail Industry from building relationships working with our customers. This knowledge is available to improve the whole performance of your oil analysis program.
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