Study on silt contamination properties of natural waters used as pressure medium

Water hydraulics using natural water (tap water, river water, seawater, etc.) as pressure medium instead of traditional mineral oil has more applications due to its special properties. The open-circuit system type is usually used in equipment, such as water hydraulic variable buoyancy system, under water tools system, water mist, and so on. However, this is a few researches on contamination characteristics of natural water which including many suspending silts. In this study, the contamination level and particle size distribution properties of different types of water, including river water, sea water and tap water, are measured by a particle counter and laser granularity apparatus. The scanning electronic microscope was used to study the topography and composition of the silt-laden in natural water. The results show that more than 70%suspendingsilt is less than 10μm and the contamination level of natural river and sea water exceed ISO4406 20/18/15, the minimum allowable level of tradition oil hydraulic system. However, tap water is cleaner and the contamination level reach the minimum recommended level 18/16/13 of normal pressure system.