The most dangerous concern for every hydraulic system is hydraulic fluid contamination. Hydraulic fluid is an unavoidable part of hydraulics and it makes the system operate. Other than power generation, the hydraulic fluid has many other functions like transferring heat, providing sealing and lubrication, and more. When the fluid is contaminated, this will inversely affect all the components through which the fluid passes. Foreign particles and water molecules entrapped in the hydraulic fluid will change the physical and chemical properties of the oil and results in inefficient system performance, accelerates component wear, and decrease the service life of the hydraulic system.
The major particles that contaminate the hydraulic fluid are air, dirt, water, heat, sludge, and chemicals. In the hydraulic system, there are certain built-in contaminants and generated contaminants. Built-in contaminants are contaminants like tiny grains, thread piece, grease glob, etc… that are left-over after manufacturing or assembly process. Generated contaminants are fine metal particles that are generated from metal-to-metal contact because of long-term operation.
From the manufacturing phase to the maintenance phase there are different ways for the contaminants to enter into the system. Contaminants enter the hydraulic system through the breather, worn seals, cylinder rod scratches, quick couplers, exposed ports, bad top-of-tank gaskets, etc… Also, there are chances for contamination while refilling fluid or when changing new hydraulic fluid.
HYDRAULIC FLUID CONTAMINATION PREVENTION
It is not completely impossible to prevent contamination. If we follow the guidelines properly, then we can protect the hydraulic system to a greater extent. Some of the tips are listed below.
Compatible Hydraulic Fluid Selection: Not all types of fluids are compatible with every hydraulic system. If a wrong fluid is selected, it will react with the materials and cause excessive wear and damage. Also, the chemical and physical properties of fluid will determine the ability of the hydraulic system to withstand heat, pressure, flow rate, etc.... While adding new hydraulic fluid, it is advised to drain and flush the existing fluid.
Proper Fluid Handling and Storage: Moisture, dust, and air are common contaminants that can easily enter the hydraulic system if the fluid is not properly handled or stored. Hydraulic fluid needs to be properly stored in a cool and dry place that is free from contaminants. While using these stored hydraulic fluids, practice FIFO stock rotation. I.e; old stock needs to be used first.
Clean the Surrounding Before Opening: Dust and dirt trapped on the hydraulic system surface can easily enter into the fluid while opening any ports or lids. To prevent this, the technician needs to clean the surroundings and system surface before disassembling. Also, it is advised to properly clean the tools that are used.
Replace the Filters at Regular intervals: Filters in the hydraulic system will clean the fluid by removing dirt and other particles. Filters will get clogged if it is used for a longer period, because of the accumulation of contaminants. In such instances, the filter needs to be replaced immediately. The use of polymeric oil filters and desiccant reservoir air-breathers will be beneficial.
Avoid Reuse or Mixing of Hydraulic Fluids: It is necessary to use new and high-quality hydraulic fluid. Reusing or mixing up of different hydraulic fluids will cause undesired outcomes. Used hydraulic fluid will be containing foreign particles and its properties might be changed because of the previous usage. Similarly, when two different hydraulic fluid is mixed together the fluid properties will definitely change and will affect the system performance.
Prevent Fluid Leakage: Leakage not only results in the fluid loss but also is an entry point for contaminants. Damaged seals, wrong selection of fittings, corrosion, etc… are major reasons for hydraulic fluid leakage and fluid contamination. It is necessary to prevent such issues with regular maintenance procedures.
Hydraulic System Analysis and Maintenance: Different testing methods are available to determine hydraulic system performance and productivity. As a part of the maintenance procedure, the technician needs to check the fluid level and also want to evaluate the presence of contaminants by analyzing fluid properties. And maintain a record for the fluid condition monitoring, and filter replacements, etc.