Organic oils & trend analyses
Year of publication: 1999
To protect the environment, so-called organic oils are often used in water protection areas. The proportion of synthetic hydraulic oils in particular, which are biodegradable more quickly than comparable mineral oils, is steadily increasing. Their technical performance has been consistently improved in recent years, and their oil life is now superior to that of conventional mineral oils. Nevertheless, organic oils and the aggregates operated with them must be controlled more carefully. Many machine manufacturers and operators document the condition of oil and machine with trend analyses, especially in the case of organic oils.
No other control measure is as simple and inexpensive as oil analyses. Trend analyses provide reliable information on the oil's continued usability, the condition of the machinery, and indicate impending wear or deteriorated degradability in good time. Machine and oil manufacturers usually only test fresh oils before they are officially approved for use. However, such fresh oils are absolutely free of mineral oil and are not contaminated. Their water content is below the practical values.
However, this ideal condition is hardly ever achieved in use. This is due to the following reasons, among others:
- many devices were originally filled with mineral oil, were not sufficiently flushed and contain residual amounts of it.
- often, even new equipment that was filled with organic oil at the factory is not completely free of mineral oil, because hydraulic components are tested with mineral oil.
- due to maintenance errors or attachments coming from plants where mineral oil is used, the organic oils may be mixed with mineral oils.
- water content increases due to condensate formation, especially when operating temperatures fluctuate widely.
- dust and other contaminants enter the operating system from the outside.
The same applies to organic oil: The biggest enemy of hydraulic systems is contamination. Comprehensive damage statistics from ALLIANZ show that about 80% of all hydraulic failures are caused by contaminants.
Solid contaminants, such as mainly dust from the environment, enter the system through the filler vent and cause abrasive wear. Wear particles and aged oil molecules are also typical representatives of solid contaminants. They can clog filters and block valves.
Liquid contaminants are mainly water and mineral oil. They frequently cause corrosive wear. An increased water content of more than 0.1% can lead to the formation of free acids through hydrolysis (splitting of the ester oil). These attack non-ferrous metals in particular. However, hoses, seals and paint coatings are not safe from them either.
If an excessive amount of mineral oil is contained in the organic oil, this can cause severe foaming or a high proportion of dissolved air in the oil. This dissolved air is often the cause of cavitation. Strong pumping noises are usually a typical sign that a cavitation-related total pump failure is not far off.
But it does not have to get that far. Before it is too late, contamination can be detected at an early stage with lubricant analyses. This is why many machine manufacturers prescribe regular lubricant analyses, especially when using organic oils. They can be carried out quickly and easily, and their low cost pays for itself within a very short time. The principle of these lubricant analyses is easy to understand. Regular analyses, in the case of construction machinery every 500 operating hours, show a trend. Slightly increased running-in wear is normal at the beginning of a component's service life. This wear rate drops immediately after the machine elements have "settled in" and the surface roughness peaks have smoothed out.
From this point on in the service life, the wear curve usually shows a typically uniform course. When the actual service life limit is reached, this course changes again to a sharp increase in the wear rate. The curve rises steeply.
An atypical increase in the wear metals during the normal service life immediately indicates an irregularity and thus imminent damage. Such anomalous values for wear, water, dust and mineral oil content are detected by the trend analyses. They provide early warning of the onset of damage. If the oil care or maintenance measures recommended by OELCHECK are then carried out, cost-intensive repairs can usually be avoided.
The use of trend analyses not only reduces maintenance costs. One of Germany's leading property insurers offers reduced premiums for insuring machinery if regular lubricant analyses are carried out when using organic oils. This is a double bonus for the wallet.
