Silicone O Rings and Hoses
Silicone is an elastomer composed of polymers with silicon, oxygen, hydrogen and carbon. Other ingredients like methyl, phenyl and vinyl can be added to create unique varieties of silicone that offer specific characteristics.
Standard and custom molded silicone o rings are popular in industries that require low closure force, physiologically neutral and electrical insulating properties. They also offer resistance to high temperatures, ozone and UV radiation.
Durometer
Silicone o rings are available in a range of durometer ratings. The durometer scale is measured in increments of five or ten, with a reading of 50 or 70 on the Shore A scale being common for most compounds. Rocket Seals offers a variety of durometer-rated silicone o rings and hoses including a food-grade safe version (PDMS, polydimethylsiloxane) for use with pressure washer hoses.
Silicone compounds are very clean and are often used in the medical and food industry because they don’t have an odor or taste. They are also very resistant to ozone, oxygen, UV radiation and many mineral and vegetable oils. They aren’t recommended for use with amines, esters and hot hydrofluoric acids.
Silicone is a very soft material and has poor tear, abrasion and tensile strength. This makes it better suited for static applications than dynamic ones. It has good flexibility and compression set resistance and is very durable in low temperatures. It is compatible with water, steam and petroleum fluids, but should not be used in acidic or halogenated applications like Skydrol, engine or transmission oil, fuels or ketones. It can be cured with peroxide or platinum to increase its temperature range or make it more electrically resistant or conductive. It’s also odorless and has very little gas permeability. Silicone is available in black, natural, brown, green, gray and transparent colors or any color assigned by the customer.
Temperature Range
Among popular O-ring materials, silicone offers one of the widest temperature ranges. Parco stocks 70-durometer red silicone O-rings that are suitable for use in applications with temperatures ranging from -80 to 300degF. They’re also resistant to ozone, vegetable oils and alcohols. Silicone is an inert material that won’t leach flavors or cause cytotoxic reactions.
Silicone O-rings hold up well at low temperatures, but they do not perform well in dynamic applications involving movement because they’re brittle when they get too cold. They also have poor tear, abrasion and tensile strength, which makes them better for static rather than dynamic sealing jobs.
Viton O-rings are a good choice for high-temperature applications because they resist both chemicals and extreme temperatures. They can handle heat up to Silicone o rings 204degC and are a good choice for engine oil, transmission fluid and lubricants, petroleum fluids and some acids. However, they’re not recommended for Skydrol, ethers with low molecular weight, esters or hot hydrofluoric acid.
Another high-temperature O-ring material is FKM, which withstands heat up to 232degC and has resistance to most fuels and lubricants. It also resists permeation, compression set and aging.
Chemical Resistant
Chemical-resistant o rings are used for applications that require seals to hold up in the face of harsh chemicals. These chemicals can include acids and bases that can wreak havoc Silicone O Rings – Supplier on the integrity of an O ring. If a seal is weak, it can break down in the presence of the corrosive solution and create a leak. This is why selecting the right o-ring material is so important.
Silicone o rings have excellent heat, ozone and corona resistance, as well as good dielectric stability. They also have one of the widest working temperature ranges of any elastomer. These properties make them an ideal choice for automotive and aerospace industries, as well as other parts that need to withstand extreme temperatures. They’re also resistant to many common oils, solvents and chemicals and are often FDA approved for use in food handling equipment.
The chemical-resistant nature of silicone o rings is a result of its high-energy silicon-oxygen bonding, which makes it more resistant to oxidation and degradation than other elastomers. It’s also extremely pliable and has very low compression set, making it an excellent o-ring for dynamic seals. It does, however, have low tensile strength and poor abrasion resistance, which means it’s best for static sealing applications.
The other main type of chemical-resistant o-ring is fluorosilicone rubber (FKM). Similar to silicone, FKMs have exceptional extreme temperature resistance but also offer acid resistant qualities. There are even FKM grades that are FDA approved for use in the presence of foods and beverages.
Odorless
The food and pharmaceutical industries often require FDA-approved silicone o rings, which are non-toxic and will not grow mold. Specially formulated silicone o rings are also inert, meaning they don’t react with chemicals. This makes them ideal for use in complex medical implant systems, where the o-rings are wedged between moving pieces.
These o-rings are flexible in low temperatures and offer excellent ozone resistance, corona resistance and dielectric stability. They also resist most petroleum products, oils and chemicals. In some cases, silicone o-rings can be damaged by more-penetrating radiation, such as neutrons.
Neoprene O-rings, which are made from polychloroprene, are able to perform in a wide range of temperatures. They are also resistant to ozone, UV light and weathering. They are also able to withstand the effects of many chemicals, including coolants and ammonia. The sulfur cure used to make neoprene O-rings provides them with good tensile strength and tear resistance, while maintaining the flexibility of the o-ring.
Fluorosilicone has a very broad temperature range (-80°F to 450°F), is resistant to many chemicals and offers superb permeation and compression set resistance. It’s also gamma and autoclavable, making it an ideal choice for military or aerospace applications.