When you need to replace your lubricating oil? If you have a large quantity of lubricating oil to change, it will burn a hole in your pocket. Therefore, most plant operators try to preserve the properties of lubricating oil, while possible.
One of the most important functions of lubricating oil is to reduce the friction between the moving parts of machinery. But there are other features to look at.
When you know that the oil should be changed? Below is a rough guide:
1. Viscosity has changed by 10%
2. Flash Point fell to 150 degrees Celsius
3. Content water reached 2%
4. TBN, or Base Total number has reduced by 20%
5. Insoluble Content increased to 5% of oil
Due the oxidation of the oil, when exposed to heat and oxygen, the viscosity of oil tend to fall. With the reduction in viscosity, the oil film friction between metal surfaces becomes more difficult to maintain. This results in metal to metal contact, micro seizures that leads to scuffing, abrasion and other damages.
In large diesel engines, fuel oil drip injected or fuel pumps, sometimes find their way to the lubrication oil sump. This has the tendency to reduce the flash point of the lubricating oil. Besides reducing the viscosity which is detrimental to lubrication, this contamination with fuel oil can be very dangerous. If there is a hotspot in any friction of cuts, this may lead to a crankcase explosion.
Water can also find its way to the lubricating oil to leak in the cooling system of water o-rings or gaskets. Besides reducing the properties of lubricating oil, the presence of water in the oil can lead to bacteria or fungi growth, which will harm the speed oil properties, as well as contribute to acid corrosion and oxidation of the oil, changing the chemical composition of oil itself. However, if the water content is less than 0.5%, it can still be removed by centrifugal purifiers.
The total base number is especially necessary for lubrication of the cylinder liner engines that operate on the basis of poor quality fuel with high - sulphur content. The base additive is used to reduce the corrosive effect of sulfuric acid fumes in cylinder.
With large diesel engine plant, lubricating oils are continually filtered and purified to reduce the insoluble particles in the oil. Special strainers containing magnets are used to trap particles of iron or carbon particles. In large diesel engines, the carbon particles are by-products of combustion while the iron particles comes from the friction gears, cams or other parts where wear down even occur.
The presence of these particles interferes with the lubrication of the bearings, most of which contain soft white - metallic coating. The particles can become embedded in the soft metal and cause the metal abrasion parts.
The content of this page are part of a page of my e-book " " General Knowledge Engineering Notes, which will help prepare candidates for the Navy Certificate of Competency Examinations. This e-book is available for free download at http://www.free-marine.com/ebook.htm
Until next time ...
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Many years of professional experience in the Navy, Facilities, Construction gave the author material for writing e-books and articles related to engineering and management. Subscribe to facworld ezine Mailto: facworld-subscribe@yahoogroups.com More information on http://www.free-marine.com and http://www.free-engineering.com
joey freeman
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