March 24th, 2021
Selecting a mechanical seal can be a difficult process with various considerations to be made. The decision-making process is largely driven by the physical parameters of the mechanism that needs sealing: how large the gap is; whether or not the equipment is dynamic or static; and so on. Complicating this further is the ubiquity of mechanical seal terminologies. There are axial shaft seals, gaskets, O-rings, radial seals, rotary lip seals, and more. What distinguishes one from the other?
This article shares several ways to technically differentiate radial from rotary lip seals; two seal types that are commonly described synonymously.
Radial Vs. Rotary Lip Seals: Is There a Difference?
A radial seal is typically installed within a bore, closing the gap between two would-be mating surfaces like a plug and a cap. Unlike rotary lip seals, they may be static or dynamic in nature. Rotary lip seals are similarly used to seal bores but rely on some relative motion between the mating components to achieve an optimal leak-free seal.
Using these definitions, it is possible to define rotary lip seals as a type of radial seal. However, as rotary lip seals are exclusively dynamic, further comparisons in this post will be between static radial seals and dynamic rotary seals. A direct result of this dynamic/static dichotomy is that radial seals are assumed to be more forgiving as they do not have to contend with regular wear from oscillating or reciprocating mating surfaces.
Conversely, all mechanical seals are contacting elements that must contend with some degree of abrasion – regardless of how intermittent. Rotary lip seals are designed to operate in environments where motion between inner and outer sealing surfaces is continuous. This means their abrasion-resistant qualities are inherently greater than static seals like D-rings and double chamfers.
Selecting Seals on a Case-by-Case Basis
Sealing applications vary dramatically from case to case or application to application. Different lubricating fluids require different elastomers or materials. Certain mechanism geometries require specific seal profiles. There is no “one-size-fits-all” solution, and although rotary lip seals are typically upheld as the gold standard for dynamic sealing applications, there will always be cases where static seals perform admirably.
Read More: What are Rotary Lip Seals?
Rotary lip seals comprised of conventional elastomeric lip seals with robust metal casings form a key part of the Saint-Gobain Seals’ solution line. With extensive experience in polymeric molding processes and fabricating custom components for specific application areas, the Saint-Gobain Seals’ team is in a prime position to offer support with fine-tuned sealing solutions for your specific use requirements. Simply contact a member of the team today if you have any questions about the performance properties of rotary lip seals.