Basic Hydraulic Filtration: A Clean System is a Happy System

Hydraulic filtration is the most critical factor for having a “healthy” hydraulic system; so why is a proactive approach to filtration habitually placed on the back burner or ignored altogether? Some may be intimidated by the concepts of hydraulic filtration or simply be unaware of what they should be doing to protect their valuable systems. Applying a few basic concepts when operating a hydraulic system can improve the overall life of the system as well as potentially save thousands of dollars in repairs to components such as damaged valves and cylinders as well as money lost during down time.

The first thing to remember is that most new oil is not clean oil therefore you should condition your fluid before it is introduced into your system. You can condition your fluid by means of a hydraulic filter cart or any other offline filtration systems. Make sure that “clean” oil is introduced into your system in order to meet your most sensitive component filtration requirements and avoid immediate particulate contamination.

There are multiple types contamination introduced into a typical hydraulic system, these can be both hard and soft particles. Hard particles include metal, carbon and silica. Soft particles can be rubber materials, fibers, and micro-organisms, all of which can lead to early system failures.

A required cleanliness levels aka. ISO codes will vary based on specific components in your system I.e. servo components, proportional valves, and different types of pumps (Gear, Vane, and Piston). An ISO code (International Standards Organization) is expressed in 3 numbers such as 19/17/14. Each number represents a contamination level code for the correlating particle size. To determine the level of contamination in your system you will need to take a sample of your oil and have it analyzed by a professional. There are several types of hydraulic filter elements available to a user such as wire mesh (for low capture efficiency), cellulose/ paper (for moderate efficiency), and woven fiberglass (for high capture efficiency), so how do we choose the proper element? When choosing a filter element there are 4 major considerations: Flow, pressure drop, dirt holding capacity and filter efficiency.

Flow: make sure that your filter meets the overall flow requirements of your system including potential flow intensification from components such as cylinders.

Pressure Drop: Pressure drop will determine the life of your element based on bypass setting, not to exceed the vessel pressure rating.

Dirt Holding Capacity: DHC is how well a filter can retain particles after they are captured and before it goes into bypass. Most reputable filter element manufacturers will publish dirt holding capacity in grams.

Efficiency: This is the percentage of captured particles of a particular micron size.

Particle contamination is the primary cause of damage to a hydraulic system; that is why it is imperative that you protect your systems. Implementing these actions is fundamental to proper hydraulic filtration and will strongly minimize the chances of premature failure to your hydraulic system. Remember that hydraulic filtration can be added to any system whether it is new or has been in commission for several years, it is never too late to start protecting your valuable equipment.

Mike Balliet
Hydraulic Specialist
[email protected]

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