What are the options for standard seal temperature operation applications outside the normal range?

Posted on Tuesday, November 21, 2017 in UEA Blog


What are the options for standard seal temperature operation applications outside the normal range?Temperature: It’s in the air, it’s in the news, and it’s always changing. We are approaching the season when the ‘snow birds’ typically pack up and head south. Looking outside on this blustery, rainy day, that sounds like a good plan. Not only do humans operate better in temperate conditions, but many mechanical devices such as seals, also operate better in mild temperatures.

As with almost everything, motion products have temperature limits that dictate what sort of environment they can operate in. Operating in the desert in the middle of the summer is a different environment than operating in northern Canada in the middle of the winter. This difference, while seemingly huge, is actually standard operating temps for our hydraulic swivels, granted other operating conditions are within reason.

Our standard operating temperatures for our hydraulic swivels is -40°F to about 220°F. Some of the components in our swivels can handle higher temperatures than others. Here is a list of our standard upper-temperature limits for our main seals:

  • Cap seal (goes between circuits): 250°F
  • Uni-directional seal (one on each end): 220°F
  • Optional Hytrel based uni-directional seal: 275°F

It’s not just the ambient outside temperature that affects the operating temperature limits of the swivel. The rotation speed, oil temp, distance from oil cooler, load type and operating pressure can all affect the limits. A swivel could operate all day long in the middle of Death Valley in the summer without any issues if all other operating parameters are within reason.

A common fallacy is comparing hydraulic swivels to hydraulic cylinders. While they do share many common parts, their operation differs. Hydraulic cylinders use very similar seals, but instead of rotating, they slide up and down the length of its stroke. This is an important difference, as heat does not build up as quickly when the lip of the seal moves linearly. In a hydraulic swivel, there can be a buildup of the head directly under the lip of the seal. So just because the hydraulic cylinder is not having temperature relating issues, doesn’t mean other components in the system won’t be affected by heat. 

This can be a big consideration when we have discussions with a new customer that is thinking about taking their existing machinery and modifying to start using a hydraulic swivel.         

These issues and others are why it’s important to us to build a good working relationship with our customers. Good communication allows us to better understand the operating conditions. This, in turn, helps UEA design and build products the meet and exceed the requirements for even the harshest environments. Interested in more information about hydraulic swivels? Check out our recent blog “Are Hydraulic Swivels Always Round?”

Brady Haugo
Sr. Design Engineer

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