High Temperature Seals
Money and lives are sometimes on the line when hydraulic equipment is in use. Operating that equipment near or beyond the temperature design limits may make the difference between catastrophe and another routine job.
When we think of equipment design limits we may be referring to the OEM’s design, but what about equipment that has been in service for a while and is now in need of repair? Can you replace hydraulic cylinder seals and return the equipment to OEM specifications? Yes you can, but you must use the correct sealing components.
So let’s talk about equipment design limits where high temperatures are concerned. Since many hydraulic cylinder seals are made of rubber and some rubber compounds begin to degrade at about 250°F, it’s important to understand high temperature limits.
What constitutes ‘high temperature’ in hydraulic sealing applications? Most hydraulic seals are NBR (Buna N) and rated at 250°F. So, is anything over 250°F high temperature? That depends.
Many engineers specify FKM for applications over 250°F. That’s a safe bet for temperatures exceeding 325°F, but what about applications between 250°F and 325°F? Do you really need the added protection of FKM at about 8 times the cost of NBR? Maybe not, because there is a middle ground.
If the equipment design limits are unknown and you want high temperature protection, use FKM. However, if you want moderate (250°F to 325°F) high temperature protection without the added cost of FKM, consider HNBR at about half the cost of FKM. You gain about 75°F degrees of protection with only a modest cost penalty.
AY Seal & Packing stocks a broad range of NBR, HNBR, and FKM hydraulic seals in both inch and metric sizes. Contact us for more details.