O-rings are an essential component in machinery across all kinds of industries and have been for well over a century. Despite their importance, the basic design of an O-ring has changed very little over the last 100 years – but the materials used to make them have undergone significant advances. Today, one of the most popular substances used in the manufacture of O-rings is silicone.

Silicone is the name applied to any synthetic compound in which siloxane is a repeating constituent part. When it comes to silicone O-rings, they are impervious to extremes of temperature. The same type of silicone rubber that is used to manufacture O-rings is also employed in a variety of other household items, from kitchen utensils to electronics and insulation to medical devices.

Strengths and weaknesses of silicone O-rings

Perhaps the biggest defining characteristic of silicone O-rings is their resistance to extreme temperatures. Capable of withstanding lows of -100°C and highs of up to 310°C, silicone O-rings can even tolerate even greater extremes for short periods of time.

As well as dealing with extremes, silicone O-rings are also extremely flexible, even in low ambient temperatures. They boast a low compression set as well, making them the perfect choice for compression force sealing and working among high temperatures and pressures. As well as being resistant to heat and cold, silicone O-rings boast tremendous resilience when exposed to ozone, acid, chemicals and oils. What’s more, the colour of the material used does not have any bearing on its effectiveness or capabilities, affording user greater aesthetic control when selecting the design of the O-ring. Silicone can be matched to any RAL or Pantone number.

On the other hand, their tensile strength is not as accomplished as certain other materials and they are prone to suffering damage from tears and abrasions. This makes them more suited to static applications than dynamic ones, since a moving part is more likely to rupture their surface. Similarly, they are not the best choice in situations exposed to naked flames and they do not offer as robust impermeability as some other O-ring materials.

Applications of Silicone O-rings

Thanks to their supreme resistance to extremes of temperature, their unparalleled flexibility and their ability to withstand exposure to all kinds of substances and gases, silicone O-rings are suitable for a wide range of applications in many different industries.

These applications include (but are not limited to) automotive manufacturing, aerospace, electronics, cooling systems, pressure cleaners and water processing equipment. Furthermore, the fact that they do not impart any discernible odour or taste to their immediate surroundings or the substances with which they come into contact makes silicone an ideal choice for O-rings in applications dealing with food production and processing, medical and pharmaceutical purposes and semiconductor systems.

In terms of specific environments, silicone O-rings are particularly useful in environments which experience dry heat, ozone exposure or contact with mineral oils with minimal additives. On the other hand, they do not perform so well in situations where they may encounter concentrated acids, ketones (such as acetone or methyl ethyl ketone [MEK]), fuels, gear lubricants or steam.

Advice from the experts

If you’re still unsure whether a silicone O-ring is the best solution to your particular conundrum, it’s always preferable to seek professional help rather than hazarding a guess and hoping for the best. Our dedicated team of experienced O-ring experts are on hand to answer any questions and offer any advice you might need – simply complete our online form, give us a call on +44 1909 560 203 or drop us an email at sales@nes-ips.com and we’ll get back to you as soon as we can.