The importance of selecting the correct elastomeric seal for critical applications cannot be underestimated. In factories and chemical plants around the globe, a leak, or perhaps a major seal failure can result in downtime, damaged equipment or an environmental incident.
In this and forthcoming issues of the Global Sealing Express, we answer the most frequently asked questions about elastomer seals.
Q - How can I tell the difference in elastomers? Is there a way to identify the composition of an elastomer?
A - In general, it is almost impossible to determine the different elastomers by appearance; most O-rings are black. Specific gravity can be one differentiator, but it can vary greatly depending on the amount and type of fillers that are used in the elastomer. A definitive way to identify a class of elastomers is by FTIR analysis. To help determine composition, a thermogravimetric analysis, can be conducted. Combining these methods can provide significant information on O-ring type and composition. These methods can be used to identify the elastomer class, for example, silicone, EPDM, FKM, etc. Note, that these tests are destructive seal tests.
Q - How should purchasing specify an elastomer?
A - Ideally, the plant engineering group should develop an elastomer specification for every plant process. This specification exactly details the elastomer type (supplier product number) and performance requirements. The purchasing group will then purchase according to this specification. If a new product is offered as a less expensive alternative, the supplier should need to document that it meets the specification regarding elastomer type, and most importantly, that it meets the specification performance criteria.
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