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O-RING ELASTOMERS FOR MECHANICAL SEALS
| To make a reliable selection of O-ring compound for use in a mechanical seal, all constituents of the sealed fluid must be known. O-rings can also be degraded by fluids used periodically to clean the pumping system. Although detailed checking of each constituent is required to ensure proper elastomer selection, a few simple guidelines can provide a starting point. | |
| Fluoroelastomer (Viton®, Fluorel™): Fluoroelastomer or fluorocarbon O-rings have excellent physical properties and compression set resistance. | |
| Recommended: Oils Water, including wastewater Acids (many) Benzene, toluene Chlorine, chlorinated solvents Ethylene glycol |
Not
recommmended: Caustics, alkalis Ketones (acetone, MEK) Amines, ammonia Ethers Acetic acid Steam |
| Ethylene Propylene (EP, EPT, EPDM): EP resists caustics, and is commonly used in pulp and paper processing. EP is the first choice for hot water and steam service. EP is rapidly attacked by petroleum oils and greases, so be sure to use silicone lubricant when installing EP O-rings. | |
| Recommended: Steam, hot water Caustics Ketones (acetone, MEK) Acetic acid Ethylene glycol Ethanol |
Not
recommmended: Oils, most lubricants Acids Benzene, toluene Hydrocarbons (aromatic and aliphatic) Ethers |
| Aflas™ (tetrafluoroethyene/propylene dipolymer): Aflas resists combinations of amines and oils, and is therefore used in sour oil and gas and in refrigeration applications. Cost is comparable to fluoroelastomers. | |
| Recommended: Sour oil and gas Oils, lubricants Amines, ammonia Steam, hot water Acids Caustics |
Not
recommmended: Toluene Non-polar solvents Ethers Ketones Chlorinated solvents Acetic acid |
| Kalrez® (perfluoroelastomer): Perfluoroelastomers resist high temperatures and a wide range of chemicals. Compression set resistance is inferior to fluoroelastomers. Cost is high, approaching 100 times that of fluoroelastomers. | |
| Recommended: Almost all chemicals |
Not
recommmended: Where other elastomers can be used |
| "Aflas"
is a registered trademark of Asahi Glass Co., Ltd. "Fluorel" is a registered trademark of 3M Viton® and Kalrez® are registered trademarks of Du Pont Dow Elastomers |
|
Copyright © 1998 Advanced Sealing
Technology