Water and oil don't mix, and for good reason. When water gets emulsified in oil, it doesn't fully dissolve, creating an emulsion. This allows water molecules to cause chemical reactions within the oil, which can have detrimental effects on the machinery it's in. So, we need an efficient solution to remove water from oil.
The oxidation reactions triggered by water's presence have harmful effects on both equipment and the oil itself. Some common issues include:
Rust and corrosion: Exposed metals react with water and oxygen over time, forming metal oxides that can lead to surface flaking and abrasion wear in the system.
Cavitation (vapor bubbles): Vapor bubbles or cavities form in a fluid when the system's pressure (such as at pump suction points) is lower than the water's vapor pressure. If these bubbles reach high-pressure zones in the system, they implode, causing surface fatigue and erosion at the collapse point.
Hydrogen embrittlement: High-strength metal can develop cracks due to hydrogen molecules. Water in the oil provides the hydrogen that triggers this embrittlement process.
Reduced lubricating properties: Oil viscosity increases with pressure, crucial for moving parts under high pressure to maintain a lubricating film on metal surfaces in contact. Water's viscosity doesn't increase with pressure, leading to increased friction between moving parts and material wear when there's excess moisture in the oil.
Hydrolysis: Water degrades oil and additives through hydrolysis, a chemical reaction where a molecule bonds with a substance. For instance, water-contaminated ester-based lubricants can react, turning into acids and alcohols. Hydrolysis is accelerated by heat, metal particles, or acids. Decreased effectiveness of protective additives: Water-induced oxidation is enhanced by heat, oxygen, and metal. This leads to the formation of oxidizing agents and free radicals, reactive components. Additives' role is to neutralize this process, but excess moisture reduces their availability, increasing oxidation. Water can also bind to hydrophilic metal surfaces or displace polar additives on metal surfaces.
Oil foaming: Water contamination can cause foaming and water ingress. Water and oxygen can lead to oxidation issues, reduced lubricating properties, and cavitation as mentioned earlier.
Overall, separating water and impurities from oil is crucial to prevent these damaging effects on machinery and ensure optimal performance and longevity of the lubricant.