Responding to customer demand, Techenomics Indonesia recently carried out oil testing that showed with the addition of regular top up, levels of foaming in Hydraulic Oil can be controlled, so as to minimize danger of damage caused by excessive foaming and ultimately reduce costs by reducing oil changes and increasing equipment availability.
Foam is a collection of small bubbles of air that accumulate on or near the surface of the fluid. Foam is an efficient thermal insulator, so the temperature of the oil can become difficult to control. The presence of air bubbles in the fluid can lead to excessive oxidation, cavitation, and the reduction of lubricating properties of the oil and hydraulics system failure.
The causes of foaming are many, but the most common include water contamination, solids contamination, mechanical issues (causing excessive aeration of the fluid), cross contamination of the fluid with the wrong lubricant, contamination of the fluid with grease and too much antifoam additive, either by incorrect formulation or by incorrect reconstruction of the additive package.
Many companies have a problem with foaming in Hydraulic Oil and consequently regularly filter their hydraulic oil to extend lubricant life.
After discovering a lot of their clients were doing just this, Techenomics Indonesia decided to carry out testing to show how to control foaming and to see if aggressive filtration affects foaming tendencies.
Six clients took part in the testing including Hexindo, Pama, Thiess, SIS, Madhani and Liebher.
The following graphs show the impact of topping up with extra oil when the oil is out of spec.
Results show that a 20% top up can reduce the foaming tendency to 87.5% (normal limit).
Future results of this study and subsequent research will be grouped according to:
2. Oil type
3. Oil hours
4. Normal operation condition
This grouping is done to classify the top up and so far the results vary, most likely caused by:
1. Different units of large capacity and small capacity, which affects the load.
2. Type of oil, the additive composition of the various brands is very influential on the oil resistance.
3. Oil hours, use of long-term and short term will have a different impact on the performance of existing additive in oil.
4. Abnormal operation conditions, over-heating, over-load, seal leaks and other.
Overall, testing shows that levels of foaming in lubricants can be controlled by regular top up. This minimises the volume of oil consumption as complete oil changes can be reduced and ultimately reduces the cost of operations as equipment availability is also improved.
The work showed that even with aggressive filtration top ups can balance the foaming tendencies. Due to the wide variance of results it is recommended that testing for foaming tendency, especially if secondary filtration is being used, should be carried out routinely.
These results will provide information for customers to understand the importance of testing foaming tendencies so as to provide good information for a quality maintenance programme and reduce the risks associated with excessive foaming in hydraulic systems and gearboxes.
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