Excess lubricant contamination can have two origins: internal and external. There are a number of contaminants such as external dust, water or humidity that are generated outside the machine and can cause the lubricating oil to become contaminated.
Other contaminants are of an internal origin, inherent to the functions fulfilled by the lubricating fluid inside the machine, and which cannot be avoided during operation. These include degradation products or wear particles that come from the machine itself. Even refrigerants can cause unwanted contamination.
Therefore, there are a number of processes that can add contaminants that are external to the actual functioning of the oil, while other contaminants are derived from the production process itself.
The industrial process in and of itself is a source of contamination for the lubricant.
One of the oil’s functions is to clean the work areas in the machinery. In this process, the oil removes impurities that can affect the components of the machinery, but it also drags and transports them to the filters in order to completely eliminate them from the lubrication system. These particles not only get the machinery dirty, but they also enter into circulation throughout the system and can cause an accelerated wear and tear of the components and, as a result, breakdowns.
This is the case, for example, of diesel engines. In addition to wear particles, the oil must also face the soot that is inherently generated during its operation. This is not an external agent that comes from a malfunction, rather it is generated as part of the engine’s own operation.
In the case of water-cooled equipment, they can also be a source of contamination, because the water and oil are in very close contact with each other in the work area. Contrary to popular belief, water and oil can mix, if there is a leak from one compartment to the other. For example, in the paper industry, water contamination is an inherent element of the production process.
Machinery located in hostile environments, with a greater amount of dust or moisture, is more susceptible to external contamination. In these cases, any operation performed with the machine, including everything from changing the lubricant or checking its levels and components, to routine maintenance tasks, can cause external agents to get into the lubrication system, adding abrasive particles or water that negatively affect the useful life of the oil and the condition of the machinery itself.
In this regard, the slightest deterioration of the sealing components, such as the poor condition of a joint, can act as the access route for these particles that then have a negative impact on the lubricant’s ability to clean.
Inadequate fillers are another common source of contamination. By introducing the wrong oil, its physicochemical conditions are altered, such as its viscosity. If the components of the oils are incompatible, they produce chemical reactions that attack the surfaces, generating sludge that clogs the machine, which in turn leads to a critical failure.
External contaminants are a common problem but, as we’ve seen, they are no less important. That’s why it’s necessary to take the appropriate measures to minimise their presence and thus avoid high costs and unforeseen events.