FEATURE IMPROVED
ROCOL PRODUCT FORMULA MEANS SAFER FOOD PROCESSING
LUBRICANTS ANALYSIS:
INTRODUCTION In today’s competitive business environment, industrial maintenance professionals are continuously in search of improved machine reliability. One of the means of achieving this is through regular lubricants (or oil) analysis. The philosophy of oil analysis as one of the maintenance techniques has drastically changed over the past few years. Those days are gone when an operator simply looking at the dipstick or through a glass could determine the oil’s remaining useful life in the machine. With the advent of technology, oil analysis has become one of the most effective programs to monitor and improve the reliability of machines or any rotating equipment.
In this article, the author has made an attemt to overview the basic concepts of oil analysis, maintenance methodologies, presence of contaminants and their detrimental effect on machines as well as on the oil and lastly, a brief description of the root cause failure analysis (RCFA).
Delivering even greater improve- ments in the production process for the food industry, ROCOL Lubricants has reformulated its already proven FOODLUBE OVERHEAD CHAIN FLUID to offer enhanced protection against wear on machinery and reduced risk of food contamination.
The new FOODLUBE OVERHEAD CHAIN FLUID, which is independently certified for food use through the globally-recognised NSF HI registration scheme, is designed specifically for the lubrication of overhead chains and rails in food production facilities.
Removal of the food contamination risk is behind the development of the new non-drip formula, which has superior adhesion properties. This ensures that the lubricant will not drip or flake off rails or chains during production, thus avoiding potential food contamination as well as eliminating the serious health and safety risk to personnel through slips and falls.
Maintenance cycles and the longevity of production machinery can be significantly improved with the use of this product thanks to its excellent penetration. The lubricant is designed to penetrate chain links and pins extremely effectively to promote smoother running and reduced wear and tear.
FOODLUBE OVERHEAD CHAIN FLUID offers unrivalled protection and water resistance and has the broad operating temperature range of -20° and 150°C.
LINK
www.rocol.com
6 ISSUE NO. 64 DECEMBER 2004 FIG.1 LUBRICANTS
Lubricating oils that are used in any rotating equipment, basically consist of two parts:
1. Base oil or base stock 2. Additives
BASE STOCK
Most base oils are mineral oils or petroleum oils. These are produced from crude oil using various refining processes. Refining normally starts with fractional distillation to solvent extraction, solvent dewaxing etc. Mineral based lubricating oils consist of millions of different hydrocarbon (compounds containing carbon and hydrogen) molecules.
ADDITIVES
Additives are chemical compounds deliberately incorporated in the base oil to enhance the existing properties and to impart additional superior properties to the oil. These can be inorganic salts, metallo-organic compounds, polymers etc. Different additives have different functions. For example, viscosity index (VI) improvers are high molecular weight polymers. At high temperature these polymers swell and their viscosity increases so that the thinning effect of the lubricating oil under this condition can be properly taken care of.
Additives
Protective Additives
Surface
1 2 3
Antiwear & EP agents
inhibitors Detergents
Rust
4 5
Dispersants
Friction Modifier
BACK TO BASICS: PART 1 Dr D Mukherjee, TIL LTD
Fig.1. shows various additives and their functions. These additives can vary from 1% to 25% in the base oil depending upon the application. Different oil companies have different additive packages but basic ingredients are same in each case. These additives are very carefully and precisely blended into the base oil. This precision is important because blending of one additive might affect proper functioning of the other additives.
It may be noted from FIG.1 that enormous number of additives is required for optimun performance of the lubricant. However, a few of these additives deserve special comments:
Antiwear (AW) and extreme pressure (EP) additives become active only under certain specific temperature and pressure. They have no effect under other conditions, thus largely reducing their costly consumption as well as minimizing other harmful side reactions.
AW additives are typically zinc dialkyl dithiophosphate (ZDDP) compounds, organic phosphates, organic sulphides and disulphides. When active they form protective layer on metal surfaces preventing adjacent asperities to come into contact. AW additives function under moderate environment of temperature while EP additives are effective under environments that are more hostile.
AW additives perform adequately up to temperature 240 - 2500C. Beyond this temperature range these additives become ineffective. Under conditions of excessive or unusually heavy load, oil temperature increases and exceeds the effective range above which the AW agents cannot offer further protection. Lubricants containing additives that protect components under extreme pressure are called extreme pressure additives or EP additives and the oil is known as EP oil. Common formulations of EP additives are compounds containing boron, phosphorous, sulphur or/and their combinations. These compounds are not activated by the pressure itself but by the increased temperature resulting from extreme pressure. These compounds under excessive high pressure release derivatives of phosphorous or sulphur. These derivatives attack the exposed metal surfaces forming iron phosphate or iron sulphide. These phosphates or sulphides then act as protective layers preventing direct contact of the adjacent asperities.
Molybdenum disulphide (commonly known as moly) and graphite are examples of solid EP additives. They are also known as anti-seize compounds. Anti-seize agents function independent of temperature and pressure.
1. Reduce friction & wear and prevent scoring & seizure
2. Prevents corrosion & rusting of metal parts in contact with the oil
3. Keep surface free of deposits 4. Keeps insolubles dispersed in the oil 5. Alter coefficient of the friction
6. Enable lubricants to flow at a low temperature
7. Swell elastomeric seals
8. Reduce the rate of viscosity change with temperature
9. Prevent forming foam
10.Retard oxidative decomposition
11.Reduces catalytic effect of metal on oxidation
Performance Additives
6
Pour point Depressant
8 7
Seal swell Agent
Viscosity modifier
9 Antifoamant 10 Antioxidant
Protective Additives
11 Deactivator Metal
Viscosity index (VI) improvers are added in order to reduce the effect of viscosity change with temperature. They retain satisfactory lubricating performance at elevated temperature. At low tempera- ture viscosity characteristics of the base stock prevails while at high temperature VI improvers retain the viscosity at satisfactory level.
It is worthwhile to mention here that inspite of all these costly additives the oil ages with time and finally needs to be replaced with fresh oil. This happens because additives just delay the break down of the oil. For example, anti- oxidants delay the oxidation process but cannot prevent it.
Additive packages are proprietary items and oil manufacturers never divulge the detailed information about the additives in their product.
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