Member Visit Stresses the Importance of Using the Right Fluid

by Eric Lanke
NFPA CEO

My travels recently took me through Philadelphia, which provided me with the opportunity to visit NFPA member Evonik Oil Additives. It was a great experience, allowing me to learn a ton about hydraulic fluids and the additives that help them perform better. The folks at Evonik, as you can imagine, are waging the good fight against the perception that “oil is oil,” and really helped me appreciate the difference that the right oil can make in the performance of hydraulic systems.

For example, I learned about viscosity indexes—which is evidently a more important factor to worry about that just plain viscosity. Seems viscosity—the thickness of the fluid—is a good thing to have at high operating temperatures, but not such a good thing at low operating temperatures. A thick fluid when the system is cold means that the system may not start, but a thin fluid when the system is hot means that it will transmit less power. So you want a hydraulic fluid to be thin at cold temperatures and thick at warm temperatures, but since most fluids naturally lose viscosity when they warm up, this can often be difficult to achieve. A viscosity index is basically the description of how good a fluid is at doing this. It measures the loss of viscosity between two standard temperatures—one “cold” and one “hot”—and the flatter the line that connects those two points on the viscosity index graph the better. The whole point of the additives that companies like Evonik manufacture is to “flatten out the line,” to make the same fluid thinner at cold temperatures and thicker at hot temperatures. It’s a tricky proposition, but I guess that’s why some people study advanced chemistry.

Using the right fluid really can make a difference in the performance of your hydraulic system.