Info Centre >> Fuel and Lube Oil Technical Manual >> 7. Lube Oil - Test Results >> 7.1 Key Condition Indicators for Lube Oils >> 7.1.2 Water
Water contamination may cause different problems in different types of lubricating oil, although corrosion is always directly associated with water ingress.
Whatever the equipment, water can displace the oil at contacting surfaces, reducing the amount of lubrication and activating surfaces which may themselves act as catalysts for degradation of the oil.
This is a particular problem with synthetic ester-based oils (e.g. many turbine lubes) which also react with any water present (hydrolyse). Water in emulsified form can increase lubricant viscosity. On occasions, it has caused gross instability and dropout of the additive package. Problems will occur, whether visible or not, in any system in the presence of more than about 0.2% water (some systems are very intolerant to water contamination).
Water is an important contaminant in many lube oil systems because of its potential to cause failure via a number of mechanisms. Water contamination within lubricating oil storage tanks can lead to microbiological growth, forming yeast, mould and bacteria that will clog filters and very rapidly corrode fuel systems.
In highly loaded lubricated contacts, particularly where oil films are thin (for example on gear teeth), water contamination can result in rapid failure through localised or general breakdown of oil film conditions. Alternatively, the mode of failure could be progressive resulting from local or generalised corrosion of components within the systems and/or through effects which impact on the functionality of the lubricant itself.
There are many potential sources of water contamination in any system including:
