For a hydraulic system, oil is everything that it requires for operation. The pressurized fluid will flow through every hydraulic component in the circuit. So, the quality of the oil needs to be maintained for maximizing the performance of the system. To ensure the cleanliness of the hydraulic fluid used, the system uses different oil filtration units to remove foreign particles. External and internal factors, environmental conditions, and many other reasons will contaminate the hydraulic fluid used.
Based on the contaminants, the contamination can be categorized into solid contamination, gel-like contamination, liquid contamination, and gaseous contamination. Solid contaminants can be dust, rust, sand, etc… that enter the system through atmospheric contact while refilling and installation, and internal factors like oil ageing and internal wear. Gel-like contaminations are originated from oil ageing and oil mixing. Moisture, leakage, chemical processes, and the high-pressure cleaner will create liquid contamination. For gaseous contaminations, the reasons include contact with ambient air, outgassing of the fluid, and leakage. The effects of these contaminations are component failures, leakage, blockage of filter elements, cavitation, corrosion, oxidation, control inaccuracies, reduced system efficiency, overheating, etc…
The primary task of a fluid conditioning unit is to monitor oil contamination and to keep the fluid clean, cool, and dry. Any system with a fluid conditioning unit will have benefits like reduced sludge accommodation, increased energy efficiency, maximum production output, operational reliability, and reduced unit cost. Depending upon the type of contaminant, various types of conditioning units can be used. The method required for removing solid particles from the fluid will be different from that required for removing water. Some interesting facts about these hydraulic fluid conditioning units can be discussed in the following sections.
To remove solid particles from the hydraulic fluid, stationary or mobile filter units or filter elements can be used in the circuit. The stationary filter units will be connected to the bypass flow of the system and these units will be dedicated. The mobile filter units are suitable for servicing or maintenance applications and this mobile unit can be placed used for temporary bypass flow filtration.
For removing water from oil, the filtration unit will utilize different approaches like the vacuum process, coalescing process, and super absorbers. The vacuum dehydrator is installed to remove 90-95% of dissolved water content from the hydraulic fluid. The vacuum dehydrator oil purification system contains automatic PLC controls and a series of electrically controlled switches. In the vacuum process, oil with water content will enter the oil vacuum system, and its temperature will be raised to about 60°C for removing water content. The dewatering system using the coalescing process will contain coalescing elements and the water content will settle on these fibers. Super absorbers with super-absorbent polymer technology are used in the fluid conditioning system to remove water content from petroleum-based fluids.
The independently operating offline oil filtration system is another category of the fluid conditioning system that can be connected to the reservoir or storage system directly. The insoluble contaminants in the oil can be removed easily using this offline filtration unit. Dirty filters can also be replaced without using any complicated tools and this makes the maintenance task simple and affordable.