Silicone O Rings
Among the many different types of o rings available, silicone o-rings stand out for their high resistance to both cold and hot temperatures. Additionally, they are highly resistant to ozone and chemical exposure such as acids, alkali, and oil.
Other common O-ring materials include Viton, a fluorocarbon that has good chemical and high temperature resistance. Nitrile o-rings are also known for their oil and fuel resistance but lack silicone’s thermal stability and cold flexibility.
High Temperature Resistance
O-rings function best within specific temperature ranges based on their unique chemical composition. Exceeding those temperatures will cause them to harden, lose their elasticity, and eventually lead to seal failure.
Silicone o rings are an ideal option for applications that require high levels of temperature stability. They are highly resistant to extreme heat, cold, UV radiation and ozone and can be compounded with various organic groups to enhance their mechanical properties.
Nitrile o-rings (NBR or buna-N) and ethylene/butylene rubber (EPR) o-rings are both widely used for their low cost and high performance. They are able to resist petroleum oils, ozone, sunlight and oxygen, and offer low compression set and abrasion resistance.
Viton o-rings are a popular choice for demanding applications due to their ability to perform in extremely harsh environments. Viton is a fluorocarbon elastomer, commonly known by the trade name DuPont FKM Viton. This material is able to withstand ozone, UV radiation, petroleum oils, engine and transmission oil, animal and vegetable fats and oils, and many other chemicals.
High Flexibility
Silicone o rings are known for their flexibility. This elasticity allows them to stretch and bend in ways other elastomers can’t, without breaking or tearing. This flexibility is due to their unique molecular makeup. Inside every silicone ring are tiny, repeating chains of molecules called polymers. These polymers are normally coiled up randomly, but when silicone rings are Silicone o rings stretched they can coil and elongate indefinitely without ever wearing out or losing their structural integrity.
This flexibility, along with their excellent resistance to heat and ozone, makes silicone O-rings ideal for use in the electronics industry and automotive applications. These o-rings are also known for their chemical and biological resistance, making them great for medical and food industries that require non-toxic products.
Specially formulated VMQ O-rings are FDA compliant and resistant to fungus, fungal attack and bacteria. They can withstand harsh environments such as mineral and vegetable oils, diluted salt solutions and engine and transmission fluids. They can also be used with petroleum-based fluids, but must be lubricated properly to prevent damage and extend lifespan.
Bio-Inertness
Silicone is a versatile synthetic elastomer that performs well in a variety of conditions. These characteristics are what make it an exceptionally common material for use in o-rings and other sealing products.
Unlike other o-ring materials, such as nitrile and Viton, silicone rubber doesn’t react with biological products, making it ideal for food production lines, medical devices, and more. This bio-inert nature also extends to the environment, where silicone o-rings are resistant to a wide range of temperatures and weather conditions.
While this versatility makes silicone an excellent Silicone o rings choice for a wide range of applications, it does have some limitations. Because of its low strength and abrasion resistance, silicone o-rings are typically used in static applications. They are not recommended for dynamic applications due to their low flex and fatigue life.
However, silicone o-rings are often used in tandem with other seal materials that can address these concerns. For instance, o-rings made of perfluorocarbon (FFKM) fluoroelastomer have similar compatibility and temperature ratings as silicone o-rings but are much more resistant to dynamic stress. This is why it is important to understand the differences between the o-rings you’re considering for your application before choosing one.
Chemical Resistance
Silicone rubber is one of the most versatile synthetic elastomers available. It can withstand a broad range of temperature extremes and has high resistance to water, oil, UV damage, ozone, chemicals, and other harsh substances.
While silicone o rings do not have excellent tear or abrasion resistance, they are well suited for static applications where damage from the elements is not a concern. However, other rubber o-ring materials can provide better durability in these scenarios.
Nitrile o-rings, for example, have better resistance to petroleum-based oils and have a higher abrasion-resistance than silicone. Viton o-rings, meanwhile, are noted for their resistance to weather and certain chemicals but do not perform as well in low temperatures or offer the same electrical insulating properties as silicone. Despite their drawbacks, silicone rubber seals remain the best choice for a wide variety of applications. They can be formulated with inert fillers to enhance specific traits, and can also be color-matched to any RAL or Pantone number for a customized look. All o-rings, regardless of material, need to be properly lubricated to work correctly.
Durability
Silicone o rings are durable and can withstand repeated use over time. This durability is measured by tensile strength, which is the amount of force required to deform or break a material at a specific point. When compared to other rubber o ring materials, such as Nitrile (FKM) or EPDM, silicone is superior in this regard.
This ability to withstand extreme temperatures is what makes silicone o rings such an essential component in numerous industries, including food & beverage, medical and pharmaceutical applications. The versatility of silicone o-rings also make them popular in electronics and automotive applications.
Viton o-rings are made of fluoroelastomer that contains strong carbon-fluorine bonds, which give it high chemical, thermal and oxidation resistance. This makes it suitable for oil and gas and other industrial applications that require a seal that will not leak or crack due to exposure to harsh chemicals and extreme temperatures. However, when compared to silicone, Viton doesn’t offer the same level of flexibility at low temperatures or electrically insulating properties. It also lacks the same resistance to petroleum-based oils and fuels as silicone.