Seals proposed for use by the food processing field are often required by law to be comprised of only the compound ingredients determined by the U.S. Food and Drug Administration (FDA) to be safe for food contact.
Such o-ring compounds must consist exclusively of the ingredients listed in the FDA's “White List” located in the Code of Federal Regulations (Title 21) section number 177.2600. It is the responsibility of the o-ring manufacturer to utilize food grade materials only from the white list of FDA sanctioned ingredients. These compounds tend to have a high compression set due to the limit of cures allowed.
Food service o-rings that have thus far met FDA white list requirements have been produced primarily from the elastomers Ethylene Propylene, Fluorocarbon, Nitrile and Silicone.