ForConstructionPros.com

The tight tolerances found in today's hydraulic systems require hydraulic fluids to be as close to "contaminant-free" as possible.

"Clean fluid is essential to the life of hydraulic systems," says Diego Navarro, service marketing manager, John Deere Construction and Forestry. "The higher the operating pressure, the cleaner the fluid needs to be."

Rudy Urbano, hydraulic consultant, Caterpillar, points out, "On a high-pressure piston pump, the only thing that separates one moving part from another is a film of oil. That film of oil is about 1 to 2 microns thick."

Caterpillar specifies an International Standards Organization (ISO) code range of 18/15 for its equipment hydraulic systems. "When you talk about an 18/15 ISO code, you're talking about [the number of allowable] particles that are 5 to 15 microns in size," Urbano notes. "So even in an ‘acceptably dirty' system at 18/15, your particles are still going to be bigger than the film of oil separating the machine components. In addition to hard particles, you also have the chemical contamination of air, heat and water."

As the size and volume of contaminants increase, equipment performance suffers, and you face the risk of premature failure of pumps and other components. Fortunately, there are precautions you can take when storing and handling fluids that can help to mitigate this risk.