The hydraulic oil should be kept clean ensuring good filtration and prevention of external as well as in-house impurities. The care of hydraulic oils starts before they are used into the system. The following points need to be kept into mind:
In a hydraulic system the operating fluid transmits forces and motion. It must have the following characteristics:
* High lubricity and protection against wear.
*High compatibility with other materials, high shear stability.
* High resistance to oxidation.
* Low compressibility.
*Low temperature expansion
* Low foaming tendency.
* Low air absorption.
* High air release ability and water separation ability.
* High boiling point.
* High density.
* High conductibility, favorable dielectric properties, non-hygroscopic, fire resistant, environmentally friendly, high filterability, high corrosion protection.
* Easy to maintain, low-cost and easy availability.