Coal Age

MAY 2017

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40 www.coalage.com May 2017 operating ideas Off line Filtration Can Cut Oil Consumption and Reduce Maintenance It's difficult to name any type of prima- ry mine production and comminution equipment that doesn't require lubrication in some form. Trucks, shovels, crushers, mills, conveyors and even electrical trans- formers need oil — and generally, lots of it. Add to that the various tanks, barrels and other containers used for oil storage and transfer, and it's easy to see why a mine or plant's productivity and cost-of-operation figures can slide smoothly upward — or quickly downward — on the presence or absence of a thin film of oil. According to oil filtration special- ist C.C. Jensen A/S (CJC), contamination causes 80% of all oil system failures. Palle Maschoreck, head of the Danish compa- ny's mining business segment, recently described his company's approach to con- tamination control and prevention to Coal Age: "We have taken technology, which is widely known and used in the global wind [turbine] industry and applied it to mining. We employ a different filtration technolo- gy — offline filtration — than the standard inline filters, which enables us to clean and keep oil very clean during operation." Maschoreck showed two photos and said, "[Here's] a clear indication of this. These are microphotos of used engine oil. The first picture is oil after only nine hours of operation — the oil is clearly dark and al- ready contaminated. This is under normal operating conditions without CJC filtration. The second picture is the same oil after 963 hours of operation using CJC filtration. There is a clear, visible difference. Imagine the impact this has on the equipment." Overall, CJC's approach for avoiding oil system failures rests on the premise that the best way to control oil contamination is to stop the contaminants from entering the system in the first place. This entails ensur- ing that all machine components are clean when installed and that oil systems are thoroughly flushed before operation. The oil system should be sealed from the en- vironment as thoroughly as possible with seals and gaskets, as well as with high-qual- ity tank breathers that provide fine particle and moisture-retention protection. The oil should be pre-filtered before coming in contact with any machine com- ponent, preferably by continuous filtration in the lube room/storage area or when transferred to machines. Proper oil con- tamination control also includes main- tenance procedures for topping up with oil, replacing parts, taking oil samples, etc. Solid particles account for the majori- ty of all failures in an oil system. The most harmful are particles of similar size or slightly larger than the dynamic tolerance between the moving parts in the oil sys- tem. Dynamic tolerances in an oil system are extremely fine. How fine? Take a look at the figures in the table below. Other modes of contamination that may play a role in system failure include water contamination, oil degradation and acidity contamination — any or all of which can reduce the protection offered by even premium oils against machine damage. CJC noted that determining whether to replace oil on the basis of time or operating hours is expensive and unnecessary. Bas- ing oil changes on its condition is the best approach — and this is where oil analy- sis can help. A good oil analysis report will answer key questions: • Is the oil suitable for further use? • Has a critical wear situation developed? • What level of contaminants is evident? • Is oil degradation speeding up? Could a severe varnish problem occur soon? The company maintains that the best method for capturing and retaining fine particles as well as water and varnish is by installing an offline filter. An offline fil- ter operates continuously, circulating the oil volume in the system many times per day. CJC said its offline oil filters remove oil degradation products such as sludge and varnish through polar attraction to the fil- ter medium. A combination of adsorption These microphotographs show engine oil after only nine hours of operation using conventional inline filtration (left), and after 963 hours with offline filtration technology. Dynamic Oil Film Component Oil film thickness in micron (μm) Journal, slide and sleeve bearings 0.5-100 Hydraulic cylinders 5-50 Engines, ring/cylinder 0.3-7 Servo and proportional valves 1-3 Gear pumps 0.5-5 Piston pumps 0.5-5 Rolling element bearings/ball bearings 0.1-3 Gears 0.1-1

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