Venting - an often neglected problem
There is always air in the oil!
Dissolved air are gas molecules which are in between oil molecules or attached to them. This dissolved air has no influence on the properties of the oil. 1l oil can hold about 20 times the volume of air in compressed form at 250bar. With undissolved air, the air molecules are in bubble form in the hydraulic oil. While air dissolves only slowly in oil, it escapes abruptly - e.g. when pressure drops. These changes are typical in a hydraulic system. Since the solubility of air in the hydraulic medium is pressure-dependent, air is expelled from the oil with each reduction in pressure when saturation is reached. Here, the comparison with a bubble bottle helps: CO2 is dissolved in the water - just like the air in the oil. Now we increase the pressure by shaking the bottle. If we now open the bottle, the pressure collapses abruptly and the CO2 flows out in bubbles.
Consequences of undissolved air in the oil
Undissolved air can thus be the cause of a wide variety of damage such as defective seals or even damaged running surfaces. Air bubble erosion, diesel effect and oil aging are the causes of this damage, which ultimately leads to cylinder failure and leakage.
What can I do to protect against such damage?
Find out in our free whitepaper, which you can download directly here.