seal design

Gallagher recently released our High Performance Elastomer Seals for the Instrumentation Industry White Paper.  This was written by Russ Schnell, an Elastomer Consultant contracted by Gallagher Fluid Seals, and a former Senior Application Engineer with the Kalrez® perfluoroelastomer parts business at DuPont.  This white paper is now available for download on our Resources page.

Below is the third and final section of the white paper, which will discuss the importance of proper seal and groove design.

Proper Seal & Groove Design

Proper seal design is a necessity for elastomer seals to perform reliably over the long term. Many of the instrument applications mentioned above use o-ring seals. The suggested compression for an elastomer o-ring seal to perform properly is typically a minimum of 16%, and a maximum of 30%. However, this range must also take into account the thermal expansion of an elastomer at elevated temperatures as well as any swell due to chemical exposure. Many of the elastomer seals used in instruments are small o-rings, which can create design issues. This is especially true for perfluoroelastomer parts which have a relatively high coefficient of thermal expansion (CTE). Fluoroelastomers have a lower CTE, making seal design easier at elevated temperatures.

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.  Original content can be found on Parker’s Blog.

A common question fielded by Parker O-ring Application Engineers is “will a (insert polymer family) O-ring work with (insert chemical mixture).” Not a day goes by where I do not field this question in some way, shape, or form. Which, honestly, makes perfect sense, because chemical compatibility is one of the two most important factors in designing a seal, the other being size. Choosing the right compound can literally make or break your seal and to the general designer, this can be a massive undertaking. There are so many rubber compound families out there and hundreds and hundreds of chemicals, so how can you know whether your seal is going to hold up? Well, today, I hope to give you a simple, and quantitative way to figure that out.