Corrate 28AS Prevents Cavitation
The phenomena known as cavitation begins as a localized, low-pressure zone that forms adjacent to the outer wall of the cylinder. This low-pressure differential is caused by the expansion and contraction of the cylinder wall due to high cylinder pressures experienced in diesel engine ignition.
Cavitation corrosion occurs when a fluid’s operational pressure drops below its vapor pressure, causing gas pockets and bubbles to form and collapse. It is often described as localized (or nucleate) boiling as the vapor bubbles collapse when they come in contact with cooler liquids and surfaces.
In the cavitation mechanism, the outside wall of the engine liner actually moves first toward, then away from the coolant causing a near vacuum for an instant and then returns to its original geometry. This rapid cylinder wall movement causes a low-pressure zone to be created in the coolant adjacent to the cylinder wall causing the surrounding coolant to boil, forming tiny bubbles. When this low-pressure zone returns to a high pressure zone, the vapor bubble collapses, causing an implosion, or pitting phenomena on the cylinder wall.
The violent implosions create tremendous shock waves which first remove the corrosion inhibitor film from the metal surface. If the film does not reform quickly, a bare, stressed, active liner surface is exposed. The resulting corrosion/erosion is localized and effectively drills small holes in the liner wall. If allowed to progress, these holes will penetrate the wall and oil will flow into the coolant when the engine is running and coolant into the oil when the engine is shut down.
Note: The expansions/contractions of the cylinder walls are more pronounced as you increase the demand for power. Thus, running the engine “hot” or over design easily contributes to the cavitation problem.
CAVITATION PREVENTION – CORRATE 28AS
Corrate 28AS acts to prevent cavitation corrosion via two mechanisms:
1) Corrate 28AS contains a premium corrosion inhibitor package that provides maximum protection under normal conditions and possesses the ability to quickly form and reform a tenacious inhibitor film under stressed conditions.
2) Corrate 28AS possesses a surface wetting-agent quality (changing the surface tension of the water) that allows the inhibitor to effectively reach the metal surface and apply a continuous protective film. It also acts to create smaller, less aggressive vapor bubbles that have a less violent collapse.