Cleanliness and Contamination in High Pressure Hydraulic Systems

Most hydraulic system failures in high-pressure hydraulic components are caused by contamination of the hydraulic fluid. The non-soluble particulates within the fluid have an abrasive quality that can limit the life of the hydraulic components and potentially cause catastrophic failure.

There are steps that should be taken to reduce the impact of inevitable dirt and contaminant issues inherent from hydraulic use and these steps should be adopted as part of regular hydraulic care maintenance.

Hydraulic Care and Maintenance to Minimize Hydraulic Fluid Contamination

All hydraulic fluid is contaminated from the beginning, but how it is maintained will affect the level of acceptable contamination.

Hydraulic fluid should be checked regularly.

  1. Filter new oil before filling a reservoir or system: New oil is not hydraulic system-ready oil; always filter new oil prior to loading.
  2. Match oil cleanliness to system requirements: Understand the requirements set by the system’s manufacturer and make sure the filtration you choose meets that level.
  3. Consider hydraulic systems designed with easily accessible filter systems; otherwise, maintenance and filter replacement could be routinely postponed.
  4. Set up a maintenance schedule based on your operational requirements, environmental conditions, where and how frequently the system is operated, and filtration system design.
  5. Clean the areas around the filter before you change it; this prevents accidentally getting dirt particles into the system.

Hydraulic Care and Maintenance to Enhance Hydraulic Cylinder Cleanliness

Most hydraulic cylinders come equipped with wipers that will effectively wipe away debris that could become lodged in the seal and enter the hydraulic fluid…for the most part. These wipers are an imperfect remedy to the dirty conditions in which most hydraulic cylinders are used. This is why basic cleaning is necessary to augment the use of the wiper. The need for this varies based on the environment where your hydraulic cylinder is working, but as you can imagine, dirty environments require more preventative measures to keep the area clean around the cylinder. As rods repetitively insert and retract from the cylinder, there is less likelihood for damaging particles to compromise seals if the surrounding area is clean. In some jobs, it is nearly impossible to eliminate all of the chances of exterior contaminates landing on and eroding seals despite their accompanying wipers. In these extreme cases, a rubber bellow can be used to protect the rod, like the ones PowerX sells. It is helpful to remember that the cleaner the equipment is kept, the longer the seals will last.


If you are working with hydraulics that warrant continuous testing for large particulates, hydraulic fluid will need to be changed. Small particles can become like sandpaper to the inside of the cylinder and its components. When this happens, “lapping” can occur which can change the actual structure of the cylinder in ways that will change the diameter of the cylinder and potentially cause the seal to fail.

Testing: On-Site or In Laboratory

Depending on the size of your cylinder and its use, you may want to take hydraulic fluid samples to a laboratory to test. These tests can clearly identify types of metals eroding into hydraulic fluid. Instead of hunting for an item that needs repair, you will be better able to identify certain bearings or gears based on the metallic components in your fluid.

If you are running a small cylinder, or do not have the means to deliver samples to a lab, there are on-site testing units available. These portable test units don’t deliver the precise results of a laboratory, but they are perfectly acceptable for general tests on units that are less likely to cause crippling failures.


Cleanliness and Contamination Vital to Hydraulic Use

Clean Hydraulic Fluid is the most important part of any hydraulic system and when systems fail, the cause is most often related to fluid contamination. Hydraulic systems rely on hydraulic fluids to transfer power and lubricate critical components. Even though hydraulics are now made with efficient wipers and filters that reduce the risk of contamination and the ill effects of cleanliness, it still remains very important to hydraulic system longevity and seal integrity that equipment be kept as clean as possible.


PowerX International specializes in 10,000 psi hydraulic systems and are here to provide you with expert and personalized service. Give one of our application engineers a call at 1-414-988-6202.


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