THE PRIMARY PURPOSE OF A HYDRAULIC FLUID is to transfer power. The concept of fluid power is based on a principle articulated by Blaise Pascal, which is usually given as follows: “Pressure applied to an enclosed fluid is transmitted undiminished to every portion of that fluid and the walls of the containing vessel” [1]. Within the context of fluid power, pressure is related to the force acting on a confined fluid as illustrated in Fig. 1 [2]. This principle has given rise to modern hydraulics, which entails highly engineered systems for efficiently controlling fluid flow to transfer energy and accomplish work.