Viton® (FKM) Material
Viton is a fluoropolymer elastomer and synthetic rubber compound that was developed by DuPont. It is a fluorinated hydrocarbon rubber designed to withstand challenging and harsh conditions. There are different grades of Viton, such as A grade that has 66% fluorine and is commonly used for O rings.
“A” grade Viton O rings are more expensive than nitrile ones because Viton has a wider temperature range, better resistance to degradation from weather, ozone, and resistance to chemicals. The extended service life of Viton reduces service and maintenance calls while providing highly reliable sealing. These factors make an investment in Viton less expensive and cost saving.
Viton O rings can withstand temperatures ranging from – 20° C up to 210° C and can withstand the effects of chemicals, oils, acids, silicone fluids, and gasses such as halogenated and aromatic hydrocarbons. They maintain a tight resilient seal in the presence of oxidation, ultraviolet (UV) exposure, fungus, and mold.
Hardness and Durometers
Hardness is the measure of the resistance a material has when force is applied. The three types of hardness are scratch, indentation, and rebound.
Durometer is the international standard for determining the hardness of objects such as rubber O rings. The increments of a durometer are increased by five or ten, such as 50, 60, 65, 70, and 75 durometer. The majority of rubber O rings have a durometer reading of 70 or 90 durometer.
The three common types of durometer gauges are Types A, M, and D. Type A is used to test soft rubber, while type D tests harder rubber. Type M is used to test soft rubber O rings that are very small.
Soft materials with a low durometer reading will easily flow into microfine grooves or fill imperfections and deformities but have wear and extruding problems. They have a durometer reading of 50 durometer.
The harder a material or the higher its durometer reading, such as 70 or 90 durometer, indicates that a rubber O ring is resistant to extrusion and can be used in dynamic applications.
Rubber O Ring Benefits
- Multiple Sizes
- Proper Hardness
- Simple Structure and Design
- Self Seating
- Tight Seal
- Cost Effective
