“Which factors are the most important to consider in regard to oil filtration?”
Contamination is a leading killer of machines and lubricants alike. To help combat this, filtration systems are frequently used. In establishing a filtration program, several factors must be considered, such as the type of filtration device, type of contaminant being filtered (water or particles), the viscosity of the lubricant, and the type and location of the machine.
A bulk storage tank and larger, more critical machines may use dedicated piping in their filtration systems, while smaller, less critical units may employ portable filtration. These portable systems can be easily transferred from one machine to another. However, to avoid cross-contamination, it is best to have a dedicated filter system for each lubricant viscosity.
The two most common types of particle filters are surface and depth media. Surface filters often are found on the suction side of a hydraulic system, while depth media filters generally are installed on an inline system. These types of filters allow a lubricant to flow through but catch any particles that might try to pass through them.
When selecting a filter, the appropriate micron rating should be considered along with the equipment’s tolerances. For example, a hydraulic system should have a filter that captures smaller particles than a filter you might use on a gearbox. Keeping this in mind will help to ensure you catch the particle sizes that pose potential harm to your machines.
When filtering a machine for water, the amount of moisture in the system should determine the type of filtration device to employ. If there is a small amount of water, a spin-on or drop-in type of filter could be utilized. These filters absorb water but are similar to a diaper in that they can only hold so much. A more complex system, such as a vacuum dehydrator, may be the best option for removing large amounts of water from a lubricant. These units use heat and suction to eliminate moisture.
Another aspect to consider is the lubricant’s viscosity. If the viscosity is low, like a machine with tight tolerances, a low micron rating should be selected. As the tolerances become greater, so do the lubricant viscosities, and a filter with a larger micron rating should be used in the application.
Having a filter with the right micron size is extremely important in a circulating system. If the micron size is too small, it could cause a restriction in the flow of lubricant.
Temperature also is critical when discussing viscosity. In cold temperatures, a lubricant may have more trouble passing through a filter than it would if the temperatures were warmer.