How to prevent contaminants in lubricating oils

One of the main functions of lubricating oils is to clean the systems in which they are used, that is to say, to eliminate both the contamination that is generated inside the machinery and any that may be introduced from outside. The loss of properties of the oil caused by the contamination is, therefore, an intrinsic and inevitable aspect for fulfilling this paramount task, but for the oil to be capable of handling this function of cleaning the systems throughout its useful life it is fundamental to keep its levels of contamination to a minimum

Good practices against the contamination of oil in its life cycle

Lubrication oil is a fluid that is sensitive to contamination during the different stages of the product, from the process of manufacture up to the moment when it is replaced.

Although the oil is bound to “get dirty” in the interior of the machinery, an excess of contamination can overload its capacity for cleaning the systems in which it is introduced, a factor that also affects the useful life of the of the oil itself and the correct operation of the machine and can in turn increase the generation of wear particles. In order to prevent this, it is as necessary to protect the oil from all kinds of external contamination as it is to apply technologies for keeping it really clean when it is in operation.

1. Choosing the right oil

A first step that is recommended for keeping the contamination of the oil under control is to invest time in choosing the most suitable type of oil for each piece of machinery and selecting a manufacturer that offers guarantees over the quality of its product.

One of the maxims that must not be overlooked is that a new oil is not a clean oil . In the process of producing the lubricating oil, in which its different components are mixed together, there are conditions that might lead to contamination by water or dust.

It is important to be aware that this kind of contamination can exist, and so it is necessary to check the colour of the new oil and subject it to tests for some of its basic properties when it is received. The timing is important here in order to be able to claim under the manufacturer’s guarantee if the oil does not meet the conditions of quality that have been promised.

2. Storage in controlled conditions

The storage conditions of the lubrication oil could be the origin of entry by water or other contaminant particles.

The usual practice for storing the oil until the time comes to use it is to keep it in metal drums, with caps of the same material, which are sensitive to variations in temperature. If the drums are stored in the open, the caps can expand and contract leaving gaps through which the contamination can penetrate.

Even when logistical difficulties make it impossible to keep the oil drums in ideal storage conditions i.e. in clean dry places, well labelled and protected from extreme weather conditions, there are measures that can be taken easily to prevent or minimise the possibilities of external contamination. For example, instead of the usual vertical positions, the drums can be stored leaning slightly so that water cannot accumulate on the caps.

3. Cleanliness of items in filling

As a general rule, in the filling, or distribution of the oil in the plant, the lubricant is not poured directly from the barrel but tools are used for its insertion, such as hoses, pumps or guns. In this process, the cleanliness of all the items that are involved is fundamental to avoid contamination.

The mere fact of having the right specific tools for every type of oil does not remove the necessity of being scrupulous in keeping it clean. The waste oil that is deposited in them is a focus of attraction for dust, and if it is not cleaned properly, it would be introduced in the machinery during the following filling operation.

4. Extraction of the used oil

Changing the oil is also a very sensitive operation, not so much because of the oil that is discarded, but because of the conditions in which the new oil will be introduced.

At the moment of replacement, the used oil presents a high degree of oxidation that acts as a catalyst for the deterioration of the new oil, negatively affecting its useful life. For that reason it is necessary to extract the largest possible quantity of old oil before introducing the new oil.

When the oil is changed and a new type is used, it will be necessary to assess the compatibility between the fluids, as small amount of contamination between non-compatible fluids can lead to a large number of problems such as accelerated oxidation and the generation of solid waste matter that can block the filtering systems.

The filtering of the oil is also usually a common practice to prevent dirt from these oils entering the machine.

5. Investment in technology to identify the type of contamination

As has been pointed out above, one of the functions of the oil in the operation is to eliminate contamination from the systems, by “dragging” the particles that are generated or are introduced in the interior of the machine. Depending on their quantity and nature, the presence of these particles may correspond to patterns of wear that are common on the operation or, on the other hand, they may be symptomatic of a potential critical failure of the machinery.

Investment in technologies that provide knowledge of the type of contamination that is caused in the oil in operation, such as the sensor systems for monitoring the oil, make it possible to adopt proactive measures that improve the condition of the machinery.

Having detailed information about the contaminating particles that are present in the lubrication oil offers the possibility of optimising the use of the cleaning and filtration systems thereby reducing the costs that arise from its replacement, cleaning and maintenance. It also makes it possible to detect the root cause of contamination problems and to diagnose the cause of a potentially critical failure for the machinery before it occurs.