6mm X 85mm ID (NBR) Buna-N 70 Duro Metric O-Ring - FDA

On a cost basis, Buna-N, nitrile, or NBR, rubber is the least expensive of the oil resistant elastomers. As a result, nitrile is one of the most widely used rubber materials due to its combination of low cost, resistance to many chemicals, and good physical properties. The acrylonitrile content of this highly polar elastomer provides excellent oil and gas permeation resistance which increases as the level of ACN increases. Nitrile should not be exposed to direct sunlight or moderate to high levels of atmospheric ozone, as rapid deterioration will result. However, NBR will accept many antidegradants, most notably PVC, which offer some degree of improvement of these properties. Nitriles are usually sulfur cured, but peroxide curing is also possible, resulting in improved compression set.

The rubber compounds in the following list all comply with Paragraph 177.2600 of Title 21, sub-paragraphs a) through d), Code of Federal Regulations, "Rubber Articles Intended for Repeated Use". It should be noted that the Food and Drug Administration does not actually approve any rubber compounds. Rather it publishes a list of permissible ingredients and the maximum allowable concentration of each. These ingredients are broken down into the following categories: Elastomers, Vulcanization Agents, Accelerators, Retarders, Activators, Antioxidants and Antizonants, Plasticizers, Fillers, Colors, Lubricants, Emulsifiers, and Miscellaneous. It is the responsibility of the manufacturer, or its compound supplier, to ensure that FDA compounds are formulated according to these guidelines, and are cured under conditions of good manufacturing practices.

Nitrile Rubber - black in color and sulfur cured - NSF (National Sanitation Foundation) certified compounds also meet FDA requirements.