If water enters hydraulic oil (e.g. condensation or through an external contamination), this has unwanted consequences as it
- accelerates the ageing of the oil,
- increases the corrosion of metallic surfaces and the wear on moved surfaces,
- reduces the lifetime of rolling bearings and performance characteristics of elastomers by swelling.
As a rule, the water should build up as quickly as possible in the tank. This is made easier by de-emulsifying oils. However, if the water droplets are to be kept floating, emulsifying oils or stabilised oils are needed, which create relatively stable emulsions up to a water content of around 2%.