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Cleaner oil brings clear benefits: the cost of industrial processes can be cut considerably by using the latest filtration and condition monitoring technology, explains Shaun Skilton, condition monitoring product sales manager for Parker Hannifin.


In the current economic climate, with rapidly rising raw material and energy costs resulting in ever tighter margins, industrial organisations must optimise the efficiency of all aspects of their operations to ensure that unnecessary costs are avoided. One area that can consume considerable resources if not properly addressed is the use of oils and lubricants. This is because, all too often, hydraulic and lubrication systems go unmonitored, allowing them to be contaminated with particles or moisture, leading to a gradual reduction in the performance of equipment and, eventually, premature failure.

Although this may be a gradual process it will inevitably increase operating costs. For example, a loss of lubricating properties will increase wear and, therefore, power consumption in high speeds shafts and bearings; this is especially pertinent in more modern equipment where tolerances can be extremely small. Once oil has become contaminated, it has to be replaced and then disposed of using approved contractors, both of which add to costs. Similarly, if machinery fails as a result of oil contamination, repair costs and the associated production downtime can have a significant impact on profits.

Although it is impossible for oils and lubricants to last forever, it is possible to use simple condition monitoring equipment, combined with a practical approach to filter replacement, to maximise the operating life of oils and lubricants. While condition monitoring is often misconceived as a complex and expensive process, in relation to hydraulic oils and lubricants, where the objective is to detect particles and moisture, it is possible to use products that are available at relatively low cost and are easy to install and use, while still providing a high level of accuracy.

For example, handheld devices are now available that can detect and measure the dielectric constant of oil, highlighting changes in the oil condition brought about the ingress of water, particle contamination, metallic content or oxidation. By using these instruments, engineers can achieve early warning of an impending system failure and, as a result, increase the operating life of machinery. While, previously, hydraulic oils and lubricating fluids needed to be analysed in a laboratory for contamination levels to be measured, requiring time, money and resources, this can now be done quickly, easily and accurately at the point of use.

Similarly, online monitoring can be carried out using a new generation of condition monitoring instruments. These devices have been designed to be fitted directly into oil lines, with a simple LED readout giving a continuous indication of particle and moisture content, together with appropriate alarm conditions. The latest online contamination monitoring instruments use extremely precise laser based technology, which is linked to integrated sensing cells to measure particles down to a few microns in size. Developed for use in industrial applications, the small self contained units are extremely robust and able to be connected to a range of hydraulic and lubrication systems.

For applications where accurately monitoring contamination levels is critical, automatic particle counters can be used to replace subjective visual test methods. Particle counters use a process called light obscuration, light blockage or light extinction. The hydraulic oil or lubricating fluid being tested is passed through a light source and the shadow of any particle suspended in the fluid is measured by way of a voltage drop across a light sensitive diode. The signal generated as a result of the shadow is dependant on the size of the particle and the speed at which it passes through the light. There are other types of particle counting but the light obscuration method is a more common and accurate method and is well regulated through ISO standards and practices.

The latest automatic particle counters are robust and portable, suitable for a wide range of industrial applications. Particle counting is a particularly efficient method of condition monitoring as it provides results in minutes, enabling action to be taken quickly if oil is found to be contaminated. The portable nature of the technology makes it suitable for use on site, while explosion-proof versions of the technology have also now been developed, allowing the counters to be used in areas where previously a hot work permit or gas detector was required.


In addition to detecting particulate contamination, particle counters can also reveal moisture in fluid systems, providing operators with a percentage volume distribution of the contamination present. Furthermore, the latest instruments feature a memory function capable of holding hundreds of test results, which can be read from the handset, printed as hard copies, or downloaded to a PC for simple analysis and distribution.

Implementing this latest generation of condition monitoring technology can enable engineers to optimise the performance, efficiency and service life of machinery, by providing them with an early warning that the condition of other system components is changing; for example, an increase in moisture content may highlight the fact that seals on cooling units are failing, while high concentrations of metallic particles can indicate that bearings are beginning to wear. However, it is important to note that monitoring oil condition to identify potential problems is only part of the process. Equally important is the ability to prevent problems occurring in the first place, by ensuring that contaminants are removed before they can cause damage.

This requires an effective proactive filter maintenance strategy. Where filter elements are fitted and subsequently forgotten about until a system malfunction occurs or a major service is carried out, the performance of industrial equipment can be significantly reduced, as the efficiency of the filter element will have fallen below its optimum level long before it is replaced. Partially clogged or blocked filters can both reduce oil circulation, making pumps consume more energy, and fail to remove potentially harmful particles effectively. At present, with the cost of a litre of oil higher than that of a filter element, it makes sense to use condition monitoring systems to identify a decline in oil quality and then to replace filters proactively.

Implementing a low cost yet effective approach to condition monitoring and filtration can have a considerable effect on a company's bottom line, reducing operating costs and optimising the performance of equipment. With increasing pressure on industrial businesses to increase the efficiency of all aspects of their operations, paying attention to the condition of hydraulic oil and lubricating fluids is arguably more important than ever.

* For further information please visit: MAINTENANCE MATTERS
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Publication:Plant & Works Engineering
Date:Sep 1, 2008
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