Clean Hydraulic Fluid – What to Look For?

Posted on January 28th, 2014 by

There are many reasons for keeping hydraulic fluid clean. Here’s one — they are critical to the efficient use of equipment for your business. The task of maintaining clean hydraulic fluid requires strong training and knowledge.

Hydraulic systems are highly sensitive to contamination, which means if you keep them clean, they will run well. On the other hand, if they get dirty, you should expect some downtime.

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Source: Fluid Power Journal

Plot your strategy

Maintenance must be a carefully planned and executed strategic initiative at your business. Start with a simple three-step program.

  1. Target the areas within your system design where contamination can occur. Look around joints, flanges and other areas where dirt, water and air may enter.
  2. Create a timeline for monitoring targeted contamination areas.
  3. Adopt a strict oil analysis program to ensure that cleanliness levels are maintained.
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Source: Marine Insight

Let’s dig in deeper

Target areas –  Two primary contaminants are found in most systems — moisture and dirt, or to be more precise, particles and water. You may easily find other contaminants such as air and heat.

The smallest particles can cause a drop in efficiencies if they’re allowed to build. Filters can trap larger particles, but you also need to control particles as small as 1 micron or 1/10th of a human hair. The reason to watch out for something so small is that machines today can typically have clearances of 1 to 5 microns. Obviously, a particle of 3 microns can start to drag the pumps and valves in the system. Keep those particle concentrations below 4 microns in smaller systems, 6 microns in a medium-sized system and 14 microns in large machines.

The next step

With those targets in mind, the next step is to meet those goals. Focus on two areas — contamination exclusions and removal. Exclusions focus on ensuring particles and moisture never find their way into the system. Removal makes use of filters to remove moisture and particles.

Exclusion should be your first priority. It can cost as much as 10 times less to keep the contaminants out compared to removing something already in the system.

Exclusion starts from the time parts are received. You must have a clean program where components are stored properly, handled cleanly, dispensed to staff cleanly and installed properly. At any point through that life cycle, contaminants can find their way in. Even brand new oil needs cleaning before it’s introduced.

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Source: Marine Insight

Oil analysis

Oil analysis validates the control measures you need to establish. For most applications, particle counting should take place using ISO 4406:99 standards. Water content should be measured according to percentage or ppm of water with the Karly Fischer water test or ASTM D6304.

These strict guidelines are easy enough to understand for an experienced engineer, but they can only be checked with a good sample. We advise taking samples from return lines in a hydraulic system from actuators if possible. This may require multiple samples from the same system.

A great system will control contaminants and make your business more efficient.

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