This may be consistent across the whole seal or in localized areas that have been exposed to the chemical media.Ĭause: Swell is caused by the ingress of media into the elastomer, as the result of a chemical similarity between the compound and the media. Visual indications: The O-ring appears larger than its original dimensions. Check the chemical compatibility of the main elastomer material types using our online guide. For the ultimate in chemical resistance combined with high temperature capability, ask about our Perlast ® perfluorolastomers (FFKM). PPE engineers can recommend the most appropriate sealing material based on your application parameters. Chemical attack is accelerated at elevated temperatures and when elastomer seals are under stress, as a result of, for example, excessive stretch or squeeze, and mechanical conditions. Solution: Correct elastomer material selection is vital to ensure the seal is compatible with the application media. Occasionally cross-link density can reduce, resulting in a softer tacky material, which leads to a loss of its original shape and integrity.
Chain scission is also possible, resulting in a reduced strength. More often than not this results in an increase in cross-link density, resulting in a hard and brittle material, with a reduced ability to provide a reaction force. Visual indications: Dependent on the chemical media being sealed, the O-ring may exhibit a number of signs including blisters, cracking, a change in hardness, or discolouration.Ĭause: Some chemicals will react with certain elastomers. Ingress of contaminants can be reduced through the use of wiper or scraper rings. Our engineers can also advise on the correct surface finish for the metalwork. Solution: Ensuring the correct lubrication for the sealing system is important, PPE can offer a range of O-ring sealing materials with improved abrasion resistance. Improper lubrication or surface finish of the metalwork can exacerbate the risk, as can ingress of abrasive contaminants into the sealing system. Visual indications: The sliding contact faces of the O-ring have a grazed surface, with excessive wear there may be deeper lacerations and breaking in places.Ĭause: Common in dynamic applications, abrasion occurs from repetitive contact between the O-ring surface and the housing resulting in excessive friction between the two.
0 kommentar(er)
