From "Interesting Times"

The case for the effective management of your oils is overwhelming according to Danny Purcell of Rayco Proactive Maintenance Systems*. The breakdown of oil results from contamination by solids or water or from the effects of heat. These conditions can adversely affect the additives and the properties of the oil. This then results in the presence of wear debris, wear metal and corrosion products in the oil. The failure of machine elements and surfaces occurs shortly afterwards.

ISO 4406

ISO 4406, "Hydraulic fluid power -- Fluids -- Method for coding level of contamination by solid particles", describes a method for coding oil according to its level of contamination. This standard details a Range Number for oils based on the number of contaminant particles per millilitre (ml) larger than 5 micron (R_5Microns) and the number of particles per litre larger than 15 micron (R_15Micron). An oil rating in terms of R_5Microns / R_15Micron defines the cleanliness of the oil. An oil that is measured to have 400 particles greater than 5 micron per ml and 65 particles greater than 15 micron per ml has an ISO number of 16/13.

Rayco Proactive Maintenance Systems recommend ISO ratings for particular applications. Examples are: ISO 13/10 for high pressure or servo hydraulic systems and ISO 14/11 for turbines and other rotating equipment.

Potential Benefits

Danny reports that efforts to control oil cleanliness within these limits can result in enormous benefits. Case studies from other industries have shown:

• Significant reduction in oil usage;
• 50% reduction in mechanical downtime hours;
• 90% reduction in incidence of specific failures;
• 850% increase in equipment life.

Effective Filtration

A process of filtration, removal of water contamination, and oil analysis is recommended to ensure that oil is kept in top condition. Danny gives the following tips for managing your oil improvement program:

• Filtration should target particle sizes 5 microns and over (It is particles in the five to ten micron range that cause the most damage to machine elements)
• In some cases particularly hydraulic systems incorporating spool valves etc. protection at 1-3 Micron size is advisable;
• Removal of water contamination in oil is vital to ensuring top oil condition;
• Support your filtration program with regular oil analysis to prove it's effectiveness;
• At least 50% of your reservoir capacity should be processed per hour for both particulate and water contamination removal;
• Analyse and upgrade contamination and exclusion and removal components such as seals, tank vents and caps and filtration;
• Evaluate your filtration systems for their ability to handle high contamination ingress (in the case of seal failure, filter failure, etc.).

Clean oil both indicates and ensures healthy equipment. Oil lubricates, cools, prevents corrosion in and removes impurities from mechanical systems. Attention to oil condition can result in a high standard of equipment performance and deliver returns in terms of lower operating costs and improved equipment reliability.