AIR IN THE HYDRAULIC SYSTEM
It must always be ensured that there are no air trapped in the hydraulic fluid (oil change, maintenance work, etc.) . Rapid compression can cause such air bubbles to heat up so much that spontaneous ignition (in the mineral oil) of the air-gas mixture can occur. The resulting increase in pressure and temperature contributes not only to oil aging, but can also damage the seals and the components in the hydraulic cylinder. This process is also known as the Diesel effect.
Up to ten percent air by volume can be dissolved in hydraulic fluid under atmospheric pressure. If the system pressure drops below the vapor pressure of the fluid, air bubbles are formed; these expand rapidly to form larger bubbles together with oil vapor. Compression processes can then result in the Diesel effect.