Types of Silicone O-Rings

Silicone orings

Types of Silicone O-Rings

O-rings are molded seals wedged between two mechanical parts to prevent fluid or gas leakage. The material the elastomer is made from can have significant impact on the ring’s performance.

Silicone orings are durable, have a wide temperature range, excellent compression set and weather resistance. They are also physiologically neutral and easily cleanable, making them ideal for food processing applications.

Temperature Resistance

Unlike other polymer types, silicone has one of the broadest working temperature ranges of any seal material. It is able to perform well at temperatures from -55°C to +232°C, with some specially compounded compounds capable of higher operating temperatures. This high-performing flexibility allows o-rings made from silicone to resist a wide variety of chemicals and environmental conditions, including ozone, UV radiation, engine and transmission oil, animal and vegetable oils, steam, diluted salt solutions and more.

At very low temperatures, o-rings made from silicone display excellent elasticity and resistance to cracking. They can also withstand exposure to freezing fluids and work well in applications with varying environmental pressures.

Silicone has good resistance to animal and vegetable oils, ozone and other environmental hazards but is vulnerable to acids and alkalis. Its chemical resistance is limited when exposed to brake fluid, phosphate ethers and some petroleum based fuels. However, it does offer superior resistance to hot water and steam, as well as low tensile strength, making it a great choice for static applications.

Chemical Resistance

Silicones have outstanding chemical resistance and can be compounded to be electrically resistant, conductive or flame retardant. They also have Silicone Parts Manufacturer very good ozone and corona resistance and are dielectrically stable. They also resist many oils, chemicals, solvents and weathering conditions. Standard silicones have very good flex and fatigue life, shear resistance and tensile strength but they do not offer much in the way of abrasion or wear. They are physiologically neutral and can be medical-grade or FDA-compliant, although platinum-cured compounds are better for ozone and UV exposure or for applications requiring low volatile matter.

Flourosilicones (FVMQ) have excellent hot air resistance but less impressive ozone and UV resistance compared to silicone. They do however have good fuel and minimal oil resistance. They are not recommended for dynamic sealing operations, but are excellent for static seals where the seal must withstand extreme temperature ranges and outside environments. They do have a poor abrasion and tear strength, so if these are important characteristics to your application you should consider using an alternative elastomer.

Moisture Resistance

Silicone ‘O’ rings are well known for their wide operational temperature range and their flexibility. They are also highly resistant to most chemicals, oils, and solvents. However, their poor abrasion and tear resistance make them better suited for static rather than dynamic applications. In addition, they do not have good tensile strength and are susceptible to water damage.

Silicone is a popular seal material for medical, food and beverage and electrical industries as it is hypoallergenic and does not leech into foodstuffs. Depending on the application, special varieties of silicone can be formulated to provide additional benefits such as flame retardant and electrical insulation.

While EPDM and silicone share many similar characteristics, it is important to determine which material is a better fit for your particular needs. ESP can assist you in making the right selection. Contact one of our expert team members today to get started!

Tensile Strength

Silicone o-rings have a very low tensile strength. As a result, they may not be suitable for dynamic or rotating applications. They also tend to tear relatively easily, so they require lubrication to prevent rapid deterioration.

Silicone is an excellent choice for use in extreme temperature environments in static applications. Its stability, resistance to high temperatures and low oxidative degradation allow it to perform in environments from minus 75-degrees up to 400-degrees Fahrenheit without brittleness or change in physical properties.

Additionally, silicone retains flexibility and compression set characteristics over one of the widest working temperature ranges of all elastomers. It is odorless, tasteless, nontoxic and physiologically neutral. It is also resistant to ozone, UV radiation, hot air and corona and has excellent insulating qualities.

Fluorosilicone rubber (FVMQ) is a variation of silicone that features improved tensile and abrasion resistance Silicone Parts Manufacturer as well as higher temperature tolerance. These specialized properties make it ideal for use in the formation of O-rings, gaskets, tubing and seals for industrial, automotive, aerospace and aviation applications. It also has enhanced resistances to non-polar solvents, fuels, oils, acids and alkaline chemicals.

Flexibility

Silicone seals offer great flexibility in both high and low temperature applications. They are also non-toxic and have very low closure force, making them a perfect fit for medical and food processing applications. Additionally, silicone is naturally transparent and easy to color prior to curing, allowing users to create custom seals in a range of colors.

Unlike EPDM or other synthetic rubbers, silicone does not require the addition of Carbon Black to improve strength and durability. This allows it to remain flexible in low temperatures, while retaining high ozone resistance and excellent weathering and aging resistance.

In static applications, silicone (VMQ) offers a large operating temperature range and high shear and tensile strength. This material is FDA compliant and resists animal fat, vegetable oil, water and ozone.

VMQ can be used in a variety of applications with temperatures from -100°F to 500°F, making it a versatile choice for many different environments. Marco is proud to offer the world’s largest inventory of silicone o-rings, including a wide selection of compounds with varying properties. Find the compound that best suits your application, then buy online quickly and easily!

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